A Chronology of Significant Historical
Developments in the Biological Sciences
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- 1800 B.C.
- Although Hammurabi's code mentions the practice of hand
pollinating date palms, the sexuality of plants was not
understood until 1694.
- c. 600 B.C.
- Thales of Miletos believed that all life came from water.
- c. 590 B.C.
- Euclid investigated and recorded some of the properties
of curved reflecting surfaces.
- c. 550 B.C.
- Anaximander saw spontaneous generation as a unique
historical event, followed by the transmutation of and
evolution of different forms. He also theorized the
existence of four basic elements, which were earth, air,
fire and water.
- c. 520 B.C.
- Alcmæon of Croton dissected animals, distinguished veins
from arteries, discovered the optic nerve, and recognized
the brain as the seat of thought.
- c. 500 B.C.
- Xenophanes examined fossils and speculated on the
evolution of life.
- c. 450 B.C.
- Empedocles of Agrigentum postulated the existence of four
humors (blood, phlegm, black bile and yellow bile),
derived from the four elements (air, water, earth and
fire), of which life was composed.
- c. 440 B.C.
- Hippocrates founded a school of rational medicine in
- c. 350 B.C.
- Aristotle made detailed observations of marine organisms,
proposed an epigenetic theory of development, attempted a
comprehensive classification of the animals, and believed
that animals could hybridize freely. His written works
included Historia Animalium, a general biology of
animals, De Partibus Animalium, a comparative
anatomy and physiology of animals, De Motu Animalium
and De Incessu Animalium, both of which concern
primarily animal locomotion, De Anima, on the
vital principle, Parva Naturalia, concerning
psychology, and De Generatione Animalium, on
- c. 300 B.C.
- Theophrastos produced two great works on plants, Historia
Plantarum, and De Causis Plantarum, in which
he pursued the classification and physiology of plants.
- c. 300 B.C.
- Herophilos dissected the human body. He is believed to be
the first to do so publicly.
- c. 300 B.C.
- Diocles wrote the first known anatomy book and was the
first to use the term "anatomy".
- c. 50-60
- Pedanius Dioscorides's De Materia Medica described
600 plants of medical value. Dioscorides also made the
first recorded use of anesthesia.
- c. 50-70
- Pliny (Gaius Plinius Secundus) the Elder's Historia
Naturalis published in 37 volumes.
- Lucius Annaeus Seneca reported that glass globules filled
with water "will aid in seeing those difficult
things which frequently escape the eye."
- Claudius Ptolemy investigated the problem of
magnification by means of curved surfaces.
- Claudius Galen performed dissections and wrote numerous
treatises on human anatomy. He was considered the
authority on anatomy long after his death by those who
accepted his word rather than following his investigative
- c. 1010
- Avicenna (Ibn Sina or Abu Ali al Hussein ibn Abdallah)
published his Canon of Medicine (Al-Quanun)
which was translated into Latin in 1473 by Gerard of
Cremona and remained a useful text well into the 17th
- c. 1235
- Roger Bacon established the importance of using
- Theodoric Borogoni of Lucca advocated the use of
narcotic-soaked sponges to put surgical subjects to
- William of Occam (or Ockham) enunciated the principle now
known as Occam's Razor: "What can be explained by
the assumption of fewer things is vainly explained by the
assumption of more things."
- c. 1450
- Nicholas Cusa (Nikolas von Cusa, Nicolaus Cusanus)
suggested that plants grew by assimilation of water.
- Leonardo da Vinci stressed the importance of using lenses
for the study of small objects. Leonardo was also an
accomplished anatomist and invented may ingenious
techniques for preparing specimens for anatomical
investigation. Unfortunately most of his written work was
lost until the eighteenth century.
- c. 1500
- Leonardo da Vinci compared animal nutrition to the
burning of a candle, and pointed out that animals could
not survive in an atmosphere that would not support
- Hieronymus Bock (Jerome Boch) arranged plants by relation
or resemblance. His was the first attempt at a natural
classification of plants.
- Conrad Gessner (Konrad Gesner) distinguished genus from
species and order from class in his classification of
- Andreas Vesalius made first modern interpretation of
anatomic structures in De Humani Corporis Fabrica.
He corrected many of the errors perpetuated by the
- Hieronymus Fracastorius (Girolamo Fracastoro) wrote On
Contagion (De contagione et contagiosis morbis et
curatione), the the first known discussion of the
phenomenon of contagious infection.
- Conrad Gessner (Konrad Gesner) published Opera
Botanica and Historia Plantarum, works which
would influence such later taxonomists as Linnaeus and
- Miguel Servet y Reves (Michael Servetus) asserted, in Christianismi
Restituto, that blood circulates from the heart to
the lungs and back to the left ventricle of the heart.
- Pierre Belon's book on birds contained a picture of a
bird skeleton and a human skeleton in which the
homologous bones in the two species were given the same
- Realdo Colombo described the passage of blood from the
right side of the heart through the lungs to the left
side of the heart.
- Volcherus Coeiter (Volcker Koyter) first observed the
blastoderm of the chick.
- Zacharias Jansen (with the help of his father, Jans)
combined two convex lenses within a tube, thus
constructing the forerunner of the compound microscope.
(Their intention was to construct a telescope.) Jansen
was an optician and counterfeiter by trade. He has also
been falsely credited with the invention of the
- Caspar Bauhin used a binomial system in the
classification of plants.
- Sanctorius Sanctorius (Santorio Santorio) published De
medicina statica aphorismi. He made quantitative
measurements of body weight, total intake, and total
excrement; he attributed losses to "insensible
- William Harvey demonstrated his findings on the
circulation of blood in lectures and discourses. He
correctly deduced the existence of capillaries although
he could not see them.
- Joseph of Aromatari held that the chick is present in the
egg before incubation.
- Gaspare Aselli demonstrated the existence of lacteal
- Publication of William Harvey's Exercitatio Anatomica
de Motu Cordis et Sanguinis in Animalibus, in which
he described the function of the circulatory system,
including the notion of the heart as a mechanical pump.
- Publication of Jean Baptiste Van Helmont's Ortus
Medicinae, including account of an experiment on
plant nutrition from which he concluded that plants
derive their substance from water. He coined the word
"gas" and described the properties of carbon
- René Descartes postulated that impulses originating in
the sensory receptors of the body were carried to the
central nervous system where they activated muscles by
what he called "reflection."
- Publication of William Harvey's Exercitationes de
Generatione Animalium with the aphorism "ex
ovo omnia" on the title page.
- Thomas Bartholin discovers the lymphatic system and
determines its relationship to the circulatory system.
- Giovanni Alfonso Borelli investigated the microscopic
structure of red blood cells and accurately noted the
regularity of stomatal movements. He later demonstrated
that locomotion in fish is primarily by the motion of the
tail rather than by the fins.
- Jan Swammerdam described red corpuscles, lymphatic
valves, and alteration in the shape of muscles during
- Nicaise Le Febvre, in Traicte de la chymie, held
that the function of air in respiration was to purify the
- Robert Boyle conducted experiments upon gases and effects
of combustion and respiration on the atmosphere.
- Marcello Malpighi conducted extensive investigations on
the anatomy and embryology of plants and animals. He
discovered the existence of capillaries in the lung of a
frog--structures predicted to exist by William Harvey
some thirty years earlier.
- Robert Hooke published Micrographia, a collection
of diverse essays dealing with the microscopic structure
of familiar substances, among which the cellular
structure of cork is fully described and illustrated. He
also described microscopic examinations of fossilized
plants and animals, comparing their microscopic structure
to that of the living organisms they resembled. He argued
for an organic origin of fossils, and suggested a
plausible mechanism for their formation.
- Robert Boyle presented his method of preserving
soft-bodied animal specimens in wine spirits.
- Nicolaus Steno recognized the homology of the mammalian
ovary with that of the egg-laying animals.
- Publication of Francesco Redi's Observations on the
Generation of Insects. Redi concluded that flies were
not produced spontaneously by rotting meat, but rather
that they hatch from eggs that are deposited on the meat
by other flies. Redi did not deny the phenomenon of
spontaneous generation in general, however.
- Publication of John Mayow's Treatise on Respiration (Tractus
duo), containing accounts of experiments on
alterations produced in air by respiration and
- Jan Swammerdam described the metamorphosis of insects,
supporting the preformation doctrine.
- Regnier de Graaf described ovarian follicles--although he
believed they were actually ova--and the passage of the
zygote to the uterus.
- Nehemiah Grew published an extensively illustrated volume
summarizing his detailed studies of plant anatomy.
- Nicolas de Malebranche elaborated the conception of emboitement
(encasement), which held that each embryo is contained
within the embryo of its parent.
- Antoni van Leeuwenhoek further improved the art of
polishing lenses of short focal length. He discovered and
described protozoa, bacteria, rotifers, and the like.
- Antoni van Leeuwenhoek discovered "animalcules"
- Nehemiah Grew suggested the true nature of ovules and
- Antoni van Leeuwenhoek described human spermatozoa and
asserted that they were capable of developing into a
child, with the egg providing only nutrient.
- Christian Huygens first published a description of
- Publication of Giovanni Alfonso Borelli's De Motu
Animalium, in which he applied mechanical principles
to the study of animal movement, and discovered that the
movement of muscles was due to the contraction the
- Publication of John Ray's Methodus Plantarum Novae,
in which he distinguished monocots from dicots and first
elaborated the biological species concept.
- Antoni van Leeuwenhoek discovered bacteria.
- John Ray's Historia Plantarum published in three
- Antoni van Leeuwenhoek made detailed observations of
capillaries in frogs' feet, bats' wings, rabbits' ears,
and the tail of an eel.
- Publication of John Ray's Synopsis of Quadrupeds and
Snakes, in which he disproved Descartes's claim that
animals are insentient, questioned the existence of
fabulous creatures, and argued against spontaneous
- Rudolph Jakob Camerarius (Camerer) published De Sexu
Plantarum Epistola, which presented a conclusive
demonstration of the sexuality of plants.
- Plantade (Dalenpatius) published fictitious figures of
homunculi in sperm cells.
- c. 1700
- Georg Ernst Stahl's phlogiston theory.
- Robert Hooke's Discourse on Earthquakes, in which he
speculates on the geological mechanisms responsible for
the distribution of fossils, is published posthumously.
- Publication of John Ray's Historia Insectorum.
- Publication of John Ray's Synopsis of Birds.
- Thomas Fairchild announced the production of the first
artificial hybrid plant.
- The famous seed-breeding establishment Vilmorin-Andrieux
et Cie was founded. It was through the work of this
concern that the sugar beet was developed during the
- Stephen Hales concluded that plants are nourished in part
by the atmosphere. He also studied the ascent of water in
plants and applied physical principles to the study of
- Stephen Hales made the first measurement of blood
- Jan Swammerdam's description of cleavage in the frog's
egg published posthumously.
- Pierre Louis Moreau de Maupertuis proposed the theory
that molecules from all parts of the body were gathered
into the gonads (later called "pangenesis") and
speculated on the causes of evolution. He also made
pointed criticisms of preformationism while advancing his
own refined form of epigeneticism.
- Charles Bonnet demonstrated the regenerative ability of
- Charles Bonnet discovered natural parthenogenesis in the
aphid. He also studied photosynthesis and epinasty in
- George Louis Leclerc de Buffon regarded spermatozoa as
"living organic molecules" which multiply in
- George Louis Leclerc de Buffon's Histoire Naturelle
asserted that species were mutable; drew attention to
- René Antoine de Réaumur showed by experiments with a
pet kite that gastric juice liquefied meat.
- James Lind called attention to the value of fresh fruits
in preventing scurvy.
- Joseph Black discovered "fixed air" (carbon
- Charles Bonnet noted the emission of bubbles by a
submerged illuminated leaf.
- Carolus Linnaeus (Carl von Linné) published Systema
Naturae, in which he introduced many of the concepts
and conventions that are still used by taxonomists today.
- Albrecht von Haller described the embryology of the
chick; later supported preformation doctrine.
- Caspar Friedrich Wolff's Theoria Generationis
proposed an epigenetic theory of development which was
opposed to preformationism and laid the basis for modern
embryology. Wolff applied the microscope to the study of
animal embryology and remarked that "the particles
which constitute all animal organs in their earliest
inception are little globules, which may be distinguished
under a microscope."
- John Hunter developed comparative approach to anatomy,
also established museums of natural history.
- British livestock breeds were improved by a thirty-year
program of selection and inbreeding undertaken by Robert
Bakewell, Collings, Bates, and others.
- Joseph Gottlieb Kölreuter (Koelreuter) published reports
describing 136 experiments in artificial hybridization.
His discovery of quantitative inheritance foreshadowed
the work of Mendel.
- Marcus Antonius Plenciz, in Opera medico-physica,
formulated the view that infectious diseases were caused
by a living agent.
- Michael Adanson advocated an empirical approach to
taxonomy based on shared characters rather than
- Charles Bonnet championed preformation doctrine.
- Henry Cavendish discovered "inflammable air"
(hydrogen), which he concluded to be a combination of
water and phlogiston, since its combustion yielded water.
- Leonhard Euler suggested a design for achromatic lenses.
- Controversy between John T. Needham and Lazarro
Spallanzani over spontaneous generation.
- John Hill introduced new techniques for macerating,
preserving and staining woody materials. He employed
alum, alcohol and carmine in preparing specimens for
- Joseph Priestley discovered oxygen and showed that it is
consumed by animals and produced by plants.
- Carl Wilhelm Scheele isolated citric, malic, lactic, and
uric acids and glycerol from natural sources and produced
oxygen from silver carbonate.
- Daniel Rutherford described "residual air". His
is the first published description of what we now know as
- Joseph Priestley and Jan Ingenhousz investigated
- Hillaire-Marin Rouelle isolated urea from urine.
- Otto Frederik Müller (Mueller) taxonomically separated
bacteria from protozoa and was able to distinguish two
distinct morphological types of bacteria: bacillum and
- Joseph Priestley produced oxygen by heating mercuric
- Lazarro Spallanzani confirmed Antoni van Leeuwenhoek's
descriptions of spermatozoa.
- Adair Crawford published the first experiments on animal
calorimetry, comparing heat production in a guinea pig
- Wilhelm Friedrich Von Gleichen-Russworm stained bacteria
with indigo and carmine.
- Antoine Lavoisier demonstrated the nature of animal
- The peculiar inheritance of human color-blindness was
reported to The Royal Society of London by M. Lort. Laws
for inheritance of sex-linked traits were fully
formulated 40 years later by Christian Friedrich Nasse.
- Johann Friedrich Blumenbach classified spermatozoa as
- Publication of Jan Ingenhousz's Experiments on
Vegetables showing that illumination was required for
oxygen production in plants. He also showed that plants
use carbon dioxide.
- Lazarro Spallanzani performed experimental artificial
fertilization in amphibians, silkmoth, and dog. Concluded
from filtration experiments that spermatozoa were
unnecessary for fertilization. Described cleavage in frog
- Antoine Lavoisier and Pierre Laplace published their
memoir on heat, in which they reached the conclusion that
respiration is a form of combustion.
- George Adams (the younger) and others devised slicing
machines (microtomes) capable of cutting sections some
1/2000 of an inch thick.
- Peter Christian Abildgaard investigated the life cycle of
a tapeworm and found that it required more than one host.
This finding was not widely accepted until it was
confirmed by Gottlob Küchenmeister 70 years later.
- Felice Fontana described the nucleolus after finding it
in the slime from an eel's skin.
- Lazarro Spallanzani extended René Antoine de Réaumur's
findings to other birds, small mammals, and finally to
humans by using himself as an experimental animal.
Digestion was clearly shown to be a chemical process
rather than a mechanical grinding of the food.
- Jean Senebier showed that it is the light and not the
heat of the sun that is effective in photosynthesis.
- Antoine Lavoisier published Traite Élémentaire de
Chimie, in which fermentation is described as the
splitting of sugar into alcohol and carbon dioxide. He
characterized the reaction as an oxidation-reduction
reaction. Lavoisier and Armand Séguin made the first
measurements of human metabolic rate.
- William Smith pointed out the relationship between
fossils and geologic strata. He worked out a method for
estimating geologic age, and laid the foundation of
- Controversy between Luigi Galvani and Alessandro Volta
over the twitching of frogs' legs led to an interest in
investigating the electrical phenomena of animals.
- Publication of Christian Konrad Sprengel's Das
Entdeckte Geheimniss der Natur im Bau und in der
Befruchtung der Blumen.
- Publication of Christian Konrad Sprengel's Die
nützlichkeit der bienen und die nothwendigkeit der
bienenzucht, von einer neuen seite dargestellt.
- Erasmus Darwin's Zoönomia published; advanced the
idea that environmental influences transformed species.
- James Hutton's Theory of the Earth published,
interpreting certain geological strata as former sea
- Lime and lemon juice were introduced into the British
navy rations to control scurvy.
- Alexander Gordon demonstrates the contagiousness of
- Jan Ingenhousz concluded that plants utilize carbon
dioxide in their nutrition. He understood that plants
carry on respiration concomitantly with photosynthesis.
- Edward Jenner used cowpox to vaccinate for smallpox.
- Baron Georges Cuvier attributed the succession of fossil
forms to a series of simultaneous extinctions caused by
- Publication of Thomas Robert Malthus's Essay on the
Principles of Population.
- Karl Friedrich Burdach coined the term
"biology" to denote the study of human
morphology, physiology and psychology.
- Jean Baptiste de Lamarck elaborated a theory of evolution
based on heritable modification of organs through
continued use and loss through disuse.
- Gottfried Treviranus and Jean Baptiste de Lamarck
independently broadened the meaning of biology to include
the study of all living things.
- Thomas Young proposes a trichromatic theory of color
vision, based on three separate receptor substances in
- Charles François Brisseau de Mirbel concluded from his
numerous observations of plant structure that "the
plant is wholly formed of a continuous cellular
membranous tissue. Plants are made up of cells, all parts
of which are in continuity and form one and the same
- Nicholas-Théodore de Saussure published experiments that
represent the first treatment of the subject of
photosynthesis using quantitative methods and modern
chemical terminology. He developed the first balanced
equation for the process.
- John Dalton enunciated his atomic theory.
- Baron Georges Cuvier published his Lesson in
Comparative Anatomy, which introduced that subject.
- Ludolf Christian Treviranus asserted that spermatozoa
were analogous to the pollen of plants.
- Louis Nicolas Vauquelin and Pierre Jean Robiquet first
isolated an amino acid, asparagine, from asparagus.
- Bénédict Prévost showed that an organism was
responsible for wheat bunt disease.
- Jean Baptiste de Lamarck investigated the microscopic
structure of plants and animals. He remarked, "It
has been recognized for a long time that the membranes
which form the envelopes of the brain, of the nerves, of
vessels, of all kinds of glands, of viscera, of muscles
and their fibers, and even the skin of the body are in
general the productions of cellular tissue. But no one,
so far as I know, has yet perceived that cellular tissue
is the general matrix of all organization and that
without this tissue no living body would be able to
exist, nor could it have been formed."
- Jean Baptiste de Lamarck's Philosophie Zoologique
emphasized the fundamental unity of life and the capacity
of species to vary; environmental influences stressed.
- Nicolas François Appert, a French chef, inventor and
bacteriologist, demonstrated a procedure for preservation
of foods by canning.
- William Hyde Wollaston isolated the second amino acid,
cystine, from a bladderstone.
- Joseph Louis Gay-Lussac deduced the equation for
- Planche observed that extracts of plant roots would turn
alcoholic solutions of guaiacum blue. The agent
responsible for this change was found to be water-soluble
- Amedo Avogadro proposed that a fixed number of molecules
of any gas will equal the molecular weight of the gas in
grams. This was not widely accepted until 1858.
- Charles Bell and François Magendie discover the
functions of the dorsal and ventral roots of spinal
- c. 1815
- Robert Brown distinguished angiosperms from gymnosperms
in his classification of the higher plants.
- Konstantin Sigizmundovich (Gottleib Sigismund Constantin)
Kirchhof reported that a glutinous component of wheat is
capable of converting starch to dextrin and sugar.
- Jean-Baptiste Biot discovered optical activity.
- Christian Heinrich Pander first described the existence
of three germ layers in chick embryos. The concept was
later extended by Karl Ernst von Baer to include all
- William Smith's Stratigraphical System of Organized
Fossils showed that certain strata have
characteristic series of fossils.
- Adelbert de Chamisso introduced the concept of
alternation of generations.
- Christian Friedrich Nasse formulated Nasse's law:
hemophilia occurs only in males and is passed on by
- John Goss observed segregation of a recessive trait in
peas, but failed to note numerical ratios. In the same
year, Alexander Seton published similar observations.
- Étienne Geoffrey St. Hilaire experimentally produced
abnormal development in chicks, providing an argument
- Thomas Andrew Knight confirmed reports of dominance,
recessivity, and segregation in peas, but did not detect
- Jean-Louis Prévost and Jean Baptiste André Dumas showed
that urea is transported by the blood.
- Henry Hickman used carbon dioxide to anesthetize animals
prior to surgery.
- Henri Dutrochet further advanced the cell principle. He
stated, "All organic tissues are actually globular
cells of exceeding smallness, which appear to be united
only by simple adhesive forces; thus all tissues, all
animal (and plant) organs, are actually only a cellular
tissue variously modified. This uniformity of finer
structure proves that organs actually differ among
themselves merely in the nature of the substances
contained in the vesicular cells of which they are
- Jean-Louis Prévost and Jean Baptiste André Dumas
repeated Lazarro Spallanzani's filtration experiments,
thus confirming the necessity of spermatozoa for
fertilization, and described cleavage in a frog egg.
- Pierre-Jean-François Turpin reported his observations of
cell division in algae.
- Karl Ernst von Baer first demonstrated the mammalian
ovum; he regarded the sperm cells as "Entozoa,"
i.e., parasites, and named them spermatozoa.
- Publication of Karl Ernst von Baer's The Embryology of
Animals which strongly opposed preformationism.
- Friedrich Wöhler synthesized the first organic compound
from inorganic components, preparing urea by reacting
lead cyanate with ammonia.
- Robert Brown first described Brownian motion.
- John Vaughan Thompson first collected and described
plankton. He also correctly described barnacles as
- Joseph Lister showed how lenses could be made which
corrected for chromatic and sperical aberration. (This is
not the same Joseph Lister who is known for antiseptic
- Karl Ernst von Baer enunciated the biogenetic law.
- Franz Julius Ferdinand Meyen reported his observations on
algae, fungi and higher plants and concluded that
"...each cell forms an independent, isolated whole;
it nourishes itself, builds itself up, and elaborates raw
nutrient materials, which it takes up, into very
different substances and structures."
- Pierre-Jean Robiquet and Boutron, also Chalard,
discovered the hydrolytic splitting of amygdalin by an
extract of defatted bitter almonds. The agent was named
"emulsin" by Justus von Liebig and Friedrich
Wöhler in 1837.
- Giovanni Battista Amici investigated the process of
fertilization in plants and was able to trace the growth
of the pollen tube through the style to the micropyle of
- Charles Lyell's Principles of Geology advanced the
theory of uniformitarianism, i.e., the view that
geological formations were explainable in terms of forces
and conditions observable at present.
- Justus von Liebig developed techniques of quantitative
analysis and applied them to biological systems. The idea
that vital activity could be explained in physicochemical
terms was an important one for investigators interested
in the nature of life.
- Robert Brown published his observations reporting the
discovery and widespread occurrence of nuclei in cells.
- Leuchs described the diastatic action of salivary
- The voyage of the Beagle, with Charles Darwin
aboard as naturalist.
- Dumortier observed the process of cell division in algae.
- Anselme Payen and Jean-François Persoz further described
and isolated diastase (amylase) in powder form from
barley malt, showed it to be heat labile, and postulated
the central importance of enzymes in biology.
- Marshall Hall described the mechanism by which a stimulus
can produce a response independently of sensation or
volition and coined the term "reflex."
- Jan Evangelista Purkinje (Purkyne) discovered sweat
glands. He later discovered the neurons in the cortex of
the cerebellum and the conducting fibers in the heart
which bear his name. He also studied visual perception
and devised the first system for classifying
- Jean-Baptiste-Joseph-Dieudonné Boussingault recommended
the use of iodized salt to cure goiter.
- Jöns Jacob Baron Berzelius demonstrated that the
hydrolysis of starch is catalyzed more efficiently by
malt diastase than by sulfuric acid and published the
first general theory of chemical catalysis.
- Agostino Bassi demonstrated that a disease of silkworms
was caused by a fungus. This discovery gave impetus to
the germ theory of disease.
- Felix Dujardin associated the "sarcode"
(protoplasm) of protozoa with life processes.
- Richard Owen discovered Trichinella.
- Peltier maintained spermatozoa to be differentiated body
- Hugo von Mohl carefully described some details of mitosis
in plants. He recorded the appearance of the cell plate
between daughter cells. He remarked, "Cell division
is everywhere easily and plainly seen...in terminal buds
and root tips."
- Charles Giles Bridle Daubeny investigated the efficiency
of different parts of the spectrum in photosynthesis.
- François Magendie demonstrated the need for dietetic
- Theodor Schwann reported the action of pepsin and
described its properties. Putrefaction and fermentation
were attributed to the action of micro-organisms.
- Christian Gottfried Ehrenberg discovered giant axons in
- Frantz Schultze's and Theodor Schwann's experiments
opposing spontaneous generation.
- Jöns Jacob Baron Berzelius classified fermentation as a
catalyzed reaction. He later identified lactic acid as a
product of muscle activity.
- René-Joachim-Henri Dutrochet recognized that chlorophyll
was necessary for photosynthesis.
- Félix Dujardin asserted that the spermatozoa are
produced in the seminiferous tubules of the testis.
- Charles Cagniard-Latour (Cagniard de la Tour) Theodor
Schwann and Friedrich-Traugott Kützing independently
announced that yeast was a living organism which was
responsible for fermentation. This began the lengthy
debate over whether fermentation was a chemical or a
- Matthias Jakob Schleiden published his Beiträge zur
Phytogenese, an important contribution to
understanding the genesis of plant tissues. He observed
nucleoli but misinterpreted their significance in
considering them as nuclei forming within nuclei. Theodor
Schwann applied the same erroneous theory of cell
formation to animal tissues but correctly emphasized that
"cells are organisms and entire animals and plants
aggregates of these organisms arranged according to
- Christian Gottfried Ehrenberg separated bacteria from
- Gerardus Johannes Mulder carried out the first systematic
studies of proteins. Mulder coined the term
- Jean-Baptiste-Joseph-Dieudonné Boussingault
quantitatively studied the balance between the elementary
constitution of the maintenance ration of a cow and that
of the excretions and the milk.
- Justus von Liebig maintained that nonliving ferments
cause fermentation. This began a controversy over whether
fermentation was a vital or a chemical process.
- Peirre-François Verhulst developed the logistic model of
- Jan Evangelista Purkinje (Purkyne) proposed the term
"protoplasm" for living matter and, together
with Hugo von Mohl, established the protoplasm concept.
- Justus von Liebig proposed that fermentation is chemical
and not dependent on living microbes.
- Jean-Pierre Lallemand held that the spermatozoa are
produced in the seminiferous tubules.
- Martin Barry expressed the belief that the spermatozoon
enters the egg.
- Publication of Justus von Liebig's Thierchemie
which united the fields of chemistry and physiology.
- Johannes Müller established a theory of specific nerve
- Justus von Liebig pointed out that organic compounds in
plants are synthesized from carbon dioxide of the
atmosphere while nitrogenous compounds are derived from
precursors in the soil.
- Hugh Miller appraised the Devonian deposits of the Old
Red Sandstone formation in Scotland, one of the most
important vertebrate-bearing sediments ever discovered.
Miller believed that the fossil record confirmed the
biblical account of creation. He published Footprints
of the Creator in 1847, and opposed evolution to his
death in 1856.
- Albrecht von Kölliker (Koelliker) traced the
histogenesis of the spermatozoa and proved that they are
differentiated tissue cells.
- Julius Robert Mayer enunciated the first law of
thermodynamics and its applicability to living organisms.
- William Bowman described the histologic structure of the
- Johann Japetus Steenstrup described the alternation of
sexual and asexual generations in plants and animals.
- Oliver Wendell Holmes observed the contagiousness of
- Richard Owen elaborated the distinction of homology and
- Justus von Liebig speculated that organic acids such as
oxalic, tartaric, or malic were intermediates in the
production of carbohydrates by plants.
- Charles Darwin made his first sketch of the theory of
- Karl Ludwig showed that the Malpighian corpuscle of the
kidney acts as a passive filter and that the waste
products in the filtrate are concentrated as it passes
through the tubules.
- John Dolland devised immersion microscopy.
- John William Draper showed that plants grown in solutions
of sodium bicarbonate can liberate oxygen in the light.
- Herrmann von Helmholtz and Julius Robert Mayer formulated
the laws of thermodynamics.
- Adolf Wilhelm Hermann Kolbe synthesized acetic acid,
previously obtainable only as the result of vital
activity. He later developed a method for the synthesis
of salicylic acid.
- Carl Theodor Ernst von Siebold characterized Protozoa as
"animals whose organization is reducible to one
cell." Later, he discovered parthenogenesis in the
- Miles Joseph Berkeley demonstrated that a mold was
responsible for potato blight. He also made important
contributions to the classification of fungi.
- Albrecht von Kölliker demonstrated that spermatozoa are
cellular products of the organism. He also extended this
finding to the ovum, from which the organism is derived
by cell division.
- Pierre-Joseph van Benedin concluded that a cysticercus is
an incomplete taenioid.
- Arnold Adolphe Berthold demonstrated by removal and
transplantation that the testis produces a blood-borne
substance conditioning sexual characteristics.
- Ignaz Semmelweis investigated the cause of puerperal
- Wilhelm Hofmeister made sketches of microspore mother
cells from Tradescantia which clearly show
chromosomes in various stages of meiosis, but he failed
to grasp their significance.
- Carl Theodor Ernst von Siebold established Protozoa as
the basic phylum of the animal kingdom.
- Henri Victor Regnault and Jules Reiset published
extensive comparative studies of respiration and
- Claude Bernard isolated glycogen from the liver, showed
that it is converted into blood glucose, and discovered
the process of gluconeogenesis.
- Augustus Volney Waller demonstrated that when nerve
fibers are cut the distal portions of the fiber
degenerate. This made it possible to trace the course of
fibers through the nervous system and demonstrated the
importance of the nucleus in the regeneration of fibers.
- Jean-Baptiste-Joseph-Dieudonné Boussingault demonstrated
that higher plants cannot utilize atmospheric nitrogen,
but only nitrates from the soil. He also demonstrated the
necessity of nitrogen for plants and animals.
- Hermann von Helmholtz measured the speed of nervous
- Lucien Corvisart coined the term "tetany".
- Albrecht von Kölliker published first textbook of
histology, Handbuch der Gewebelehre.
- Hermann Friedrich Stannius tied ligatures between the
sinus venosus and the atrium, and between the atrium and
the ventricles of a frog heart, and demonstrated that the
sinus is the pacemaker of the heart, yet the atria and
ventricles are capable of independent, spontaneous
- Gottlob Friedrich Heinrich Küchenmeister demonstrated
that cysticerci (bladderworms) are the preadult forms of
- George Newport observed the penetration of the vitelline
membrane of the frog egg by the sperm.
- Heinrich Schröder (Schroeder) and Theodor von Dusch
showed that bacteria could be removed from air by
filtering it through cotton-wool.
- Louis Pasteur discovered microbial fermentation of beet
- Claude Bernard maintained that all organs liberated into
the tissue fluids special substances which assisted in
maintaining the constancy of the internal environment.
- Thomas Addison described the syndrome associated with the
deterioration of the human adrenal cortex (Addison's
disease). This is beyond question the first major
achievement of clinical endocrinology.
- Nathanael Pringsheim observed sperm penetration of the
egg of Oedogonium.
- Lucien Corvisart described trypsin, also used pepsin
- The first of the aniline dyes, eosin, is synthesized.
This dye would later prove useful for selectively
staining cytoplasmic proteins.
- Edme-Félix-Alfred Vulpian applied a solution of ferric
chloride to slices of the adrenal glands and noted that
the medulla stained green while the cortex did not. He
also noted that the same reaction was given by samples of
venous blood leaving the adrenal, but not by arterial
blood entering the gland. To account for these
observations, he assumed that the medulla synthesized a
substance that was liberated into the circulation.
- Carl Friedrich Wilhelm Ludwig develops perfusion
techniques for keeping animal organs alive after their
removal from the body. He also invented the kymograph,
mercurial blood pump and a device for measuring the rate
of blood flow. Ludwig was the first to study the role of
the nervous system in blood flow and secretory function.
- Lord Kelvin (William Thomson) computed the age of the
solar system as 25 million years (later revised to 40
- Discovery of the first Neanderthal remains.
- Albrecht von Kölliker discovered "sarcosomes"
(mitochondria) in muscle cells.
- Claude Bernard demonstrated the formation of glycogen by
the liver. This was the first demonstration of a
- Louis Pasteur demonstrated that lactic acid fermentation
is carried out by living bacteria.
- Stanislao Cannizzaro demonstrated the validity of
- Louis Pasteur noted that Penicillium molds
fermented only dextrotartaric acid and did not attack the
levo isomer. Thus he developed a practical method for
separating compounds which are identical except for the
spatial arrangement of the substituent group.
- Carmine, a comercially available fabric stain, was found
to stain cell nuclei more intensely than the cytoplasm.
- Rudolf Virchow applied the cell theory to problems of
pathology and disease and set forth the illuminating
principle that the outward symptoms of disease are merely
the reflections of impairment at the level of cellular
organization. He also advanced the notion that all cells
arise from pre-existing cells: "Omnis cellula e
- Friedrich August Kekulé von Stradonitz proposes that
carbon atoms can form chains.
- Philip Lutley Sclater studied the geographical
distribution of birds.
- Joint announcement by Charles Darwin and Alfred Russell
Wallace of the theory of natural selection.
- Publication of Charles Darwin's On the Origin of
Species argued for natural selection as a factor in
organic evolution. More importantly, it established
evolution as an acceptable theory in the minds of most
- Adolf Wilhelm Hermann Kolbe synthesized salicylic acid.
- Louis Pasteur states his aphorism, "Omne vivum e
- Alfred Russell Wallace claimed that a sharp boundary
exists between the Australian and Oriental faunal
regions. The "Wallace line of faunal
delimitation" separated the Philippines from the
Sanghir Islands and Borneo from Celebes, and ran through
part of the Malay Archipelago.
- Jean Louis René Antoine Édouard Claparéde discovered
giant axons in annelid worms.
- Thomas Graham's work on understanding the colloidal state
of matter advanced the understanding of protoplasmic
- Max Schultze established the protoplasm concept and,
after noting the essential similarity between the cell
contents of protozoa, plants and animals, concluded that
"the cell is an accumulation of living substance or
protoplasm definitely delimited in space and possessing a
cell membrane and nucleus."
- Fossil remains of Archaeopteryx lithographica
found in jurassic limestone deposits in a stone quarry in
- Julius von Sachs produced experimental evidence that
starch was a product of photosynthesis.
- Max Joseph von Pettenkofer devised an apparatus for
analyzing respiratory gas exchange, thus making possible
indirect calorimetry by the determination of respiratory
- Danielewski experimentally separated trypsin from
pancreatic amylase by differential adsorption.
- Henry Walter Bates observed mimicry of distasteful or
poisonous species by harmless, palatable species in the
lepidoptera and suggests that the mimics enjoy protection
from predation because of their resemblance.
- Karl Remigius Fresenius first used a solid culture medium
(potato) for micro-organisms.
- Ernst Haeckel (Häckel) outlines the essential elements
of modern zoological classification.
- Max Schultze observed plasmodesmata.
- Louis Pasteur's demolition of the doctrine of spontaneous
- Controversy between Carl Nägeli and Robert Koch
regarding pleomorphism versus genetic distinctness of
- Ernst Felix Emmanuel Hoppe-Seyler performed the first
crystallization of a protein: hemoglobin.
- Baron Joseph Lister instituted the practice of antiseptic
surgery and the use of carbolic acid as a disinfectant.
- Friedrich August Kekulé von Stradonitz devises a ring
model for the structural formula of benzene, supposedly
after dreaming about six monkeys holding one another by
- The stain hematoxylin was found to stain cell nuclei more
strongly than their cytoplasm.
- Gregor Mendel published his investigations of plant
hybrids and their subsequent behavior. His fundamental
discoveries lay forgotten for 34 years.
- Max Schultze discovered the existence of two types of
receptor cells in the retina.
- Ernst Heinrich Haeckel (Häckel) hypothesizes that the
nucleus of a cell transmits its hereditary information.
- Ernst Heinrich Haeckel (Häckel) first used the term
"ecology" to describe the study of living
organisms and their interactions with other organisms and
with their environment.
- Aleksandr Onufriyevich Kovalevsky demonstrated the
similarity between Amphioxus and the larval stages
of tunicates and established the chordate status of the
- Aleksandr Onufriyevich Kovalevsky extended the germ layer
concept of Christian Heinrich Pander and Karl Ernst von
Baer to include the invertebrates, establishing an
important embryologic unity in the animal kingdom.
- Joseph Lister reported his method of antiseptic surgery.
- Charles Darwin elaborated the theory of pangenesis and
gave it its name.
- Herrmann von Helmholtz proposed the resonance theory of
- Jean-Baptiste-Joseph-Dieudonné Boussingault pointed out
that plants require oxygen for photosynthesis.
- Paul Langerhans, studying the structure of the pancreas,
noted specialized groups or islands of cells that were
especially well supplied with microscopic blood vessels.
- Justus von Liebig proposed that all ferments were
chemical reactions rather than vital processes.
- Johann Friedrich Miescher isolated a substance which he
called "nuclein" from the nuclei of white blood
cells that was soluble in alkalis but not in acids. This
substance came to be known as nucleic acid. Miescher also
discovered that the amount of carbon dioxide in the blood
affects the respiratory rate.
- Louis Pasteur conclusively demonstrated that yeast was
necessary for fermentation as it could then be carried
out. He distinguished two kinds of ferments,
"organized ferments" such as yeast or lactic
acid bacteria, and "unorganized ferments" like
pepsin and amylase.
- Fagge concluded that degeneration, atrophy, or loss of
the thyroid gland resulted in cretinism.
- Lambert Adolphe Jacques Quetelet showed the importance of
statistical analysis for biologists and laid the
foundation of biometry.
- Publication of Charles Darwin's Descent of Man, in
which the role of sexual selection in evolution is
described for the first time.
- C. Ore used chloral hydrate as an intravenous anesthetic.
- Ferdinand Julius Cohn coined the term
"bacterium" and founded the study of
- Carl Friedrich Wilhelm Ludwig and Eduard Friedrich
Wilhelm Pflüger studied the processes of gas exchange in
the blood and showed that oxidation occurs in the tissues
rather than in the blood.
- Anton Dohrn established the Naples Biological Station.
- The Challenger expedition greatly extended knowledge of
the extent and variety of marine life.
- Anton Schneider observed and described the behavior of
nuclear filaments (chromosomes) during cell division in
his study of the platyhelminth Mesostoma. His
account was the first accurate description of the process
of mitosis in animal cells.
- Sir William Withey Gull recognized and described the
disease known as Gull's disease--myxoedema with the
atrophy of the thyroid gland--which he regarded correctly
as the adult form of cretinism.
- Wilhelm His in Über unsere Körperform suggested
mechanical explanations for morphological changes in the
- Ernst Haeckel (Häckel) established the taxonomic
position of the Chordata, and proposed the
"Gastrea" as the hypothetical ancestor to all
- Oscar Hertwig showed that the head of the spermatozoon
becomes a pronucleus and combines with the female
pronucleus as the zygote nucleus and established the
concept that fertilization is the conjugation of two
- Eduard Strasburger accurately described the processes of
mitotic cell division.
- Hans Buchner reported the reversible transformation of
anthrax bacillus into hay bacillus. It isn't known
whether he made an error in identification or simply used
- Ferdinand Julius Cohn studied the formation of spores in Bacillus
subtilis. Cohn also assisted Robert Koch in his work
- Robert Koch showed that anthrax was caused by a specific
organism. Koch's postulates for proving that a particular
micro-organism is the cause of a particular disease
greatly advanced the Germ Theory of Disease. They are
still used today in slightly modified form.
- Wilhelm Friedrich Kühne proposed the term enzyme
(meaning "in yeast") and distinguished enzymes
from the micro-organisms that produce them.
- Gabriel Madeleine Camille Dareste described the
successful production of developmental monstrosities by
- Ernst Abbe, of the Zeiss Optical Works, developed the
first oil-immersion objective microscope lens.
- Francis Maitland Balfour observed that the medullary
region of the adrenal gland was derived from ectodermal
rudiments that also gave rise to parts of the sympathetic
nervous system, while the cortex arose from mesodermal
- Walther Flemming described and named
"chromatin," "mitosis" and the
"spireme", made the first accurate counts of
chromosome numbers and accurately figured the
"longitudinal splitting" of chromosomes.
- Union of the gamete nuclei in syngamy was reported by
Hermann Fol in an animal and by Fredrick Schmitz in a
- Albrecht Kossel isolated nucleoproteins from the heads of
fish sperm cells.
- Charles and Francis Darwin showed that a phototropic
"influence" is transmitted from the tip of a
unilaterally illuminated plant to the basal regions.
- Alphonse Laveran demonstrated that the causative agent in
malaria is a protozoan.
- Sydney Ringer investigated the influence of inorganic
ions on heart contraction, making possible an analysis of
heart metabolism and the replacement of body fluids.
Developed Ringer's solutions for the perfusion of
isolated tissues. Studied the use of body temperature as
a diagnostic indicator.
- Walther Flemming, Eduard Strasburger, Edouard van
Beneden, and others elucidated the essential facts of
cell division and stressed the importance of the
qualitative and quantitative equality of chromosome
distribution to daughter cells.
- Louis Pasteur gave a public demonstration of the
effectiveness of his anthrax vaccine.
- Élie Metchnikoff studied the role of phagocytosis in the
immune systems of starfish and Daphnia.
- Takaki reduced the incidence of beriberi in the Japanese
navy by dietary improvements.
- Wilhelm Theodor Engelmann discovered that red light was
the most effective in photosynthesis. His experimental
method was one of the most elegant ever conceived.
- Robert Koch announced his method for isolating bacteria
in pure culture by plating them on solid media (first
gelatin, later agar).
- Eduard Strasburger coined the terms "cytoplasm"
- The Albatross, Under the direction of the U. S.
Fish Commission, further extended knowledge of the extent
and variety of marine life.
- Camillo Golgi and Santiago Ramon y Cajal developed and
refined the silver nitrate technique to give a completely
new picture of the intricate relationships between
- Max Rubner discovered that metabolic rate is proportional
to the surface area of the body.
- Pierre Émile Duclaux introduced the custom of
designating an enzyme by the by the name of the substrate
on which its action was first reported and adding the
suffix "- ase".
- Edouard van Beneden announced the principles of genetic
continuity of chromosomes and reported the occurrence of
chromosome reduction at germ cell formation. The sperm
and egg are haploid and fertilization restores the
diploid chromosome number.
- Wilhelm Roux described the time of determination of the
main axes of the frog embryo. In the same year he
correctly theorized the role of chromosomes in heredity.
- Oscar Hertwig originated the term "mesenchyme,"
a protoplasmic network filled with a fluid intercellular
substance. It may be derived from all three germ layers,
but is primarily mesodermal in origin, and gives rise to
a variety of tissues: primarily connective tissue.
- Karl Georg Friedrich Rudolf Leuckart and A. P. Thomas
independently worked out the life cycle of sheep liver
flukes in detail. This was the first time that the
complexity of the life cycle of these organisms,
including its use of snails as intermediate hosts, was
- Wilhelm Theodor Engelmann discovered photosynthesis in
- Christian Joachim Gram invented his staining method for
the classification of bacteria.
- Élie Metchnikoff proposed the cellular theory of
- Eduard Friedrich Wilhelm Pflüger, by allowing frog eggs
to cleave under pressure, showed that abnormal cleavage
patterns do not preclude formation of a normal embryo.
- Walther Flemming, Eduard Strasburger and Edouard van
Beneden demonstrated that chromosome doubling occurs by a
process of longitudinal splitting. Strasburger described
and named the prophase, metaphase and anaphase stages of
- Max Rubner extended the work of Justus von Liebig by
making quantitative determinations of the energy values
of certain foods. His work made possible a scientific
explanation for metabolism and a basis for the study of
- Julius Kollman described the phenomenon of neoteny as
observed in the axolotl form of Ambystoma tigrinum.
- Svante Arrhenius and Friedrich W. Ostwald independently
defined acids as substances which release hydrogen ions
when dissolved in water to become negatively charged ions
highly capable of reacting with other compounds.
- Identification of the cell nucleus as the basis for
inheritance was independently reported by Oscar Hertwig,
Eduard Strasburger, Albrecht von Kölliker, and August
- Karl Rabl theorized the individuality of chromosomes in
all stages of the cell cycle.
- Walther Flemming observed sister chromatids passing to
opposite poles of the cell during mitosis.
- Louis Pasteur treated Joseph Meister for rabies.
- Emil Christian Hansen instituted pure culture starters in
the fermentation of beer.
- Wilhelm Roux formulated the mosaic theory of development
after his work on early development in frog eggs.
- August Weismann formulated the germ plasm theory which
held that the germ plasm was separate from the
somatoplasm and was continuous from generation to
- Ernst Abbe, of the Zeiss Optical Works, developed the
apochromatic microscope lens.
- C. A. MacMunn discovered histohematins, later renamed
- Francis Galton devised a new useful statistical tool, the
- Sir Victor Alexander Haden Horsley induced both cretinism
and myxoedema in monkeys by experimentally removing the
- Pierre Marie fully described the constellation of
symptoms termed acromegaly.
- The Woods Hole Biological Station was established.
- Oscar Minkowski associated acromegaly with a
hyperfunctional pituitary gland.
- August Weismann elaborated an all-encompassing theory of
chromosome behavior during cell division and
fertilization and predicted the occurrence of meiosis.
Wilhelm Roux put forth the suggestion that the linearly
arranged qualities of the chromosomes were equally
transmitted to both daughter cells at meiosis.
- Edouard van Beneden demonstrated chromosome reduction in
gamete maturation, thereby confirming August Weismann's
- George Henry Falconer Nuttall and Josef Fodor found that
blood from an animal that had been exposed to anthrax
hindered the growth of anthrax bacilli.
- Emil Fischer elaborated the structural patterns of
- Ernst Haeckel (Häckel), after studying the radiolarians
brought back from the Challenger expedition and
elaborated the concept of organic form and symmetry.
- Zuntz, Geppert, Wilbur Olin Atwater, and others perfected
instruments and techniques for indirect calorimetry.
- Wilhelm Roux's experimental production of a half-embryo
by killing one blastomere of the two-celled frog embryo.
- Theodor Boveri verified August Weismann's predictions of
chromosome reduction by direct observation in Ascaris.
- Heinrich Wilhelm Gottfried Waldeyer named the chromosome.
- Francis Galton formulated the law of ancestral
inheritance, a statistical description of the relative
contributions to heredity made by one's ancestors.
- Charles Edward Brown-Séquard injected macerated testes
from other animals into his own body and believed he
obtained rejuvenating effects. Though erroneous, these
conclusions were influential in inaugurating the
administration of endocrine gland extracts as an
- Richard Hertwig and Emile Maupas independently
demonstrated exchange of micronuclei in conjugation by Paramecium.
- Baron Joseph von Mering and Oscar Minkowski duplicated
the symptoms of diabetes in the dog by experimental
excision of the pancreas. They obtained further
presumptive evidence for the endocrine function of the
islets of Langerhans in 1893.
- Richard Altmann described procedures for staining
mitochondria, studied their distribution, and postulated
them to have metabolic and genetic autonomy.
- The numerical equality of paternal and maternal
chromosomes at fertilization was established by Theodor
Boveri in Germany and Jean-Louis-Léon Guignard in
- Theobald Smith first demonstrated the transmission of a
disease by an arthropod vector: the infection of cattle
with the sporozoan Babesia by the tick Boophilus.
- Emil Adolf von Behring discovered antibodies.
- Heinrich Wilhelm Gottfried Waldeyer proposed the neuron
theory of the nervous system.
- Hans Buchner proposes the existence of antibacterial
proteins in blood serum which he called
"alexines". This began a protracted debate with
Metchnikoff, who championed a cellular theory of
- George Redmayne Murray prepared emulsions of dried sheep
thyroid in glycerine. He used these with considerable
success on patients suffering from hypothyroidism.
- Hans Dreisch discovered that each of the first several
blastomeres of the sea urchin egg would, after being
separated by shaking, develop into a complete embryo.
Dreisch's theory of totipotency contradicted Wilhelm
Roux's mosaic theory.
- Marie Eugene François Thomas Dubois discovered Java man
and named it Pithecanthropus erectus, now known as
- Dmitri Iosifovich Ivanovski discovered a disease-causing
agent smaller than bacteria: viruses.
- Publication of August Weismann's book Das Keimplasma (The
Germ Plasm) emphasized meiosis as an exact mechanism
of chromosome distribution.
- Oscar Hertwig obtained twin embryos in the newt by
constricting the egg.
- Wilhelm Ostwald proved enzymes are catalysts.
- Louis Antoine Marie Joseph Dollo pointed out the
irreversibility of evolution.
- Wilhelm His investigated the specialized conducting
tissue of the atrioventricular node and bundle of the
- Hans Dreisch expounded the view that all nuclei of an
organism were equipotential but varied in their activity
in accordance with the differentiation of tissues.
- William Bateson's Materials for the Study of Variation
emphasized the importance of discontinuous variations,
foreshadowing the rediscovery of Mendel's work.
- Karl Pearson published the first in a long series of
contributions to the mathematical theory of evolution.
Methods for analyzing statistical frequency distributions
were developed in detail.
- Emil Fischer conducted an extensive series of
investigations which still form the basis for our notions
of enzyme specificity.
- Conway Lloyd Morgan established the basic principles in
the study of animal behavior including his famous canon
which stated that the actions of an animal should be
interpreted in terms of the simplest mental processes.
- William Maddock Bayliss and Ernest Henry Starling studied
electric currents in the mammalian heart.
- George Oliver and Edward Albert Sharpey-Schäfer
(Schaefer) first demonstrated the action of a specific
hormone: the effect of an extract of the adrenal gland on
blood vessels and muscle contraction.Upon injection into
normal animals it produced a striking elevation in blood
- Born made heteroplastic grafts of parts of frog and toad
- Wilhelm Roux's Archiv für Entwicklungsmechanik der
Organismen was founded.
- David Bruce investigated the life cycle of the protistan
blood parasite Trypanosoma and the role of the
tse-tse fly in its transmission.
- Wilhelm Konrad Röntgen (Roentgen) discovered x-rays,
which were soon to be applied in the visualization of
bodily structures and in the induction of genetic
mutations (both intentionally and accidentally).
- Adolf Magnus-Levy found by means of direct calorimetric
measurements that persons with myxoedema have a lowered
heat production. He also found that administration of
thyroid preparations to normal or myxoedemic patients
raised the metabolic level.
- Theobald Smith produced a hemorrhagic deficiency disease
in guinea pigs deprived of leafy foods.
- James Mark Baldwin elaborated the Baldwin effect, which
is the belief that selection of genotypes will be
channeled in the same direction as nonhereditary adaptive
- The Russian Hydrographic Survey of the Biology of Lake
Baikal was undertaken. This survey found several unique
endemic freshwater animals that have become extinct in
the rest of the world.
- Eugen Baumann reported that the thyroid contained an
appreciable concentration of iodine in organic
combinations. He also reported that persons inhabiting
coastal areas contained more thyroid iodine than persons
living further inland.
- Herbert Edward Durham and Max von Gruber discovered
specific agglutination, and Fernand Isidore Widal found
that blood serum from a typhoid patient would agglutinate
typhoid bacilli, thus introducing the process of
- Christiaan Eijkman produced experimental polyneuritis in
chickens by feeding them polished rice, and called
attention to rice hulls as containing the preventive
agent of human beriberi. This work identified the first
known vitamin deficiency disease.
- Wilhelm Ostwald clearly demonstrated that the iodine of
the thyroid is firmly bound to a globulin-like protein
and introduced the term thyroglobulin.
- Oscar Hertwig centrifuged frog eggs and demonstrated the
effect of yolk distribution on cleavage.
- Karl Ferdinand Braun invented the oscilloscope.
- Eduard Buchner resolved the Liebig-Pasteur controversy by
producing fermentation in cell-free yeast extracts
containing zymase. Although he demonstrated that living
yeast cells were not necessary for fermentation, this in
no way proved that Liebig's proposed mechanism was
- Gabriel Bertrand coined the term "coenzyme" to
designate inorganic substances which were necessary to
activate certain enzymes.
- John Jacob Abel and A. C. Crawford isolated the first
hormone, later named epinephrine by Jokichl Takamine.
- The Canadian Geological Survey found rich fossil beds
containing Upper Cretaceous dinosaur fauna along the Red
Deer River in Alberta.
- A. Huot discovered that some fish have aglomerular
kidneys, proving that renal tubules can secrete and
- Ronald Ross elucidated the life-cycle of Plasmodium.
- Sir Charles Scott Sherrington deduced the existence of
synapses by showing that individual nerve cells could
exert integrative influences on other nerve cells by
graded excitatory or inhibitory synaptic actions.
- C. Benda and Camillo Golgi described mitochondria and
Golgi bodies in great detail and named them. The Golgi
apparatus was first observed in 1855, but Golgi's silver
nitrate impregnation method made more detailed
observation of this important inclusion possible in the
nerve cells he studied.
- Croft-Hill announced the first enzymatic synthesis, that
- Charles Reid Barnes proposed the term
- Double fertilization in plants was described by Sergey
- Walther Flemming determined chromosome number as 24 pairs
- Henry Fairfield Osborn enunciated the concept of adaptive
radiation in evolution.
- Walter Bradford Cannon used x-rays to study the movements
of the digestive system.
- William Bate Hardy pointed out that many of the
appearances of cytoplasm were artifacts of the staining
and fixing methods that were employed; therefore, the
existence of cytoplasmic structures should be confirmed
by alternative methods.
- The First International Congress of Genetics held in
- The German chemical firm of Beyer introduced
acetylsalicylic acid under the name "Aspirin".
- Richard Altmann renamed "nuclein" "nucleic
- Hugo DeVries (Holland), Karl Correns (Germany), and Erich
von Tschermak-Seysenegg (Austria) claimed to have
independently discovered and verified Gregor Mendel's
principles, marking the beginning of modern genetics.
- The Yellow Fever Commission, led by Walter Reed,
investigated the transmission of yellow fever in Havana,
- Curt Herbst used calcium-free sea water to separate
blastomeres of the sea urchin.
- Charles William Andrews discovered numerous early higher
primate remains in the Fayum Depression region east of
- T. C. Chaimberlain theorized the freshwater origin of the
vertebrates based on the discovery of early vertebrate
fossils in the Old Red Sandstone deposits, which he
believed to have had a freshwater origin.
- Karl Landsteiner discovered the A, B and O blood groups
- Jacques Loeb induced artificial parthenogenesis in frog
and sea urchin eggs by mechanically stimulating them.
- Friedel found that powdered leaves can liberate oxygen
when resuspended and illuminated.
- T. B. Aldrich and Jokichl Takamine isolated a substance
with hormone activity from the adrenal medulla and named
- Hermann Henking and others reported an "accessory
chromosome" in spermatozoa, later identified as the
- Thomas Harrison Montgomery Jr. noticed the homologous
pairing of maternal and paternal chromosomes at synapsis
prior to the reductive division.
- Franz Hofmeister articulates his enzyme theory of life:
for every vital reaction there is a specific enzyme
responsible. This view shortly became widely accepted.
- Hugo De Vries's Mutationslehre advanced the thesis
that species are not continuously connected but arise
through sudden large changes.
- Hans Spemann performed constriction experiments on newt
- George Henry Falconer Nuttall investigated the
serological relationships of animals by the precipitin
- Karl Landsteiner discovered the AB blood group.
- Clarence Erwin McClung theorized that certain chromosomes
whose synaptic mates were different in appearance or
entirely absent, e. g. Hermann Henking's accessory
chromosomes, were responsible for sex determination.
- Emil Fischer and Franz Hofmeister demonstrated that
proteins are polypeptides.
- William Bateson coined the terms F1, F2, allelomorphism,
homozygote, and heterozygote. He also listed some 26
different cases of established allelomorphism in wheat,
maize, peas, snapdragon, Datura, Oenothera,
mouse, cattle, fowl, and man.
- Charles Robert Richet investigated anaphylaxis and gave
it its name.
- William Maddock Bayliss and Ernest Henry Starling
discovered secretin, a hormone produced by the intestinal
mucosa which acted principally on the pancreas.
- Walter Stanborough Sutton and Theodor Boveri pointed out
the parallelism between chromosome behavior and
Mendelism, closing the gap between cytology and heredity.
- The concepts of phenotype, genotype and selection were
introduced and clearly defined by Wilhelm Ludwig
- Wilhelm Roux showed that the point of entrance of the
sperm marks the future mid-ventral line of the frog.
- Carl Neuberg first used the term biochemistry.
- Ross Granville Harrison obtained experimental induction
of the lens by transplanting the optic cup.
- Stoltz determined the chemical formula for epinephrine
and achieved a total chemical synthesis of the substance.
- Herbert Spencer Jennings studied the orientation behavior
of the Protozoa.
- Sir Arthur Harden and W. J. Young isolated the first
organic coenzyme: cozymase. They clearly demonstrated
that fermentation required the simultaneous presence of
both a colloidal heat labile fraction and a diffusible,
low molecular weight, heat stable coenzyme, later found
to be NAD. They also demonstrated the necessity of
phosphate in alcoholic fermentation by zymase.
- George Henry Falconer Nuttall demonstrated the importance
of intestinal bacteria in digestion.
- Ernest Henry Starling introduced the word hormone.
- F. Knoop deduced the beta-oxidation of fatty acids.
- Frederick Frost Blackman published Optima and Limiting
Factors, in which he applied physicochemical ideas to
biological problems. He pointed out that photosynthesis
involved several processes, its rate being determined by
several possible limiting factors.
- John Scott Haldane and John Gillies Priestly investigated
the role of carbon dioxide in the regulation of
- Lucien Claude Cuénot discovered the first lethal allele:
the yellow coat color allele in mice.
- Richard Adolf Zsigmondy applied the centrifuge to the
study of colloids, making a more detailed understanding
of protoplasmic constituents possible.
- N. M. Stevens and Edmund Beecher Wilson extended the
findings of cytology to the interpretation of sex
- William Bateson and Reginald Crundall Punnett reported
the discovery of two new genetic principles: linkage and
- Woodworth and William Ernest Castle introduced Drosophila
as new experimental material for genetic studies.
- Christiaan Eijkman found the anti-beriberi agent to be a
water-soluble component of rice polishings.
- Sir Fredrick Gowland Hopkins first sought to explain
dietary deficiency by a biochemical investigation of the
lack of essential amino acids in the diet.
- Willem Einthoven invented the electrocardiogram.
- Tawara discovered the atrioventricular node of the heart.
- Mikhail Semenovitch Tswett (Tsvett) first used the
technique of chromatography. He used the technique to
separate plant pigments: hence, its name.
- The Yellow Fever Commission, led by William Gorgas
effectively eliminated malaria and yellow fever in the
Panama Canal Zone by eradicating the Aëdes and Anopheles
- Richard Willstätter and coworkers discovered the
chemical structure of the chlorophyll pigments.
- Sir Arthur Keith and M. J. Flack discovered the
sinoatrial node of the heart and recognized is role as
the heart's pacemaker.
- Sir Walter Morley Fletcher and Sir Fredrick Gowland
Hopkins showed that lactic acid is formed quantitatively
from glucose during anaerobic muscle contraction. Hopkins
also showed that part of the lactic acid is oxidized to
furnish energy for the synthesis of glycogen from the
remaining lactic acid.
- H. V. Wilson convincingly demonstrated the high level of
cell individuality in phenomena of coalescence and
regeneration in sponges.
- Ross Granville Harrison developed new techniques for
culturing and studying isolated cell or tissue fragments
apart from the intact whole organism.
- Lutz proved that the gigas mutation in the evening
primrose contained twice the usual chromosome number.
This led to the analysis and artificial production of
- Bertram Borden Boltwood first proposed the use of
radioactivity data to determine the age of minerals.
- Theodor Boveri demonstrated that the chromosomes have
qualitatively different effects on development by
removing individual chromosomes from developing sea
urchin eggs. Only those cells that contained a full
complement of chromosomes developed normally.
- Otto Schoetensack discovered the mandible of a primitive
hominid in a sandpit in Mauer, Germany. This specimen has
been referred to as "Heidelberg Man" and is a
less archaic form of Homo erectus than Java Man.
- Charles Rupert Stockard studied the effects of chemicals
on embryologic development and produced cyclopia and
other monstrosities by the use of lithium and other
- Heribert Nilsson-Ehle Analyzed the inheritance of color
in wheat and provided a useful model for the further
analysis of continuously variable characters.
- Archibald Edward Garrod recognized that gene products are
proteins. He also was the first to carry out detailed
studies of genetic diseases in humans. His work was
largely ignored until 1940.
- Godfrey Harold Hardy, a Cambridge mathematician, and
Wilhelm Weinberg, a Stuttgart physician, independently
formulated the theorem that in the absence of mutation
and selection, the frequency of a gene in any large,
randomly mating population will reach an equilibrium in
one generation and remain in equilibrium thereafter
regardless of whether the gene is dominant or recessive.
Also, the genotypic frequencies of a population in
equilibrium with two alleles with frequencies p
and q are given by the formula p2
+ 2pq + q2. This theorem forms
the mathematical basis for population genetics.
- Wilhelm Johannsen demonstrated that natural selection
could not act on genetically pure lines but can only
isolate existing genotypes. Therefore, natural selection
can only influence evolutionary change if there is a
source of genetic variability. Johannsen also was the
first to use the terms "genotype" and
- William Ernest Castle and John Charles Phillips
transplanted an ovary from a black guinea pig into a
white one and showed that it would still produce black
offspring if mated to a black male. This was intended to
show that the hereditary characteristics of germ cells is
unaffected by somatic influences.
- F. A. Janssens suggested that the chiasmata observed
between synaptic chromosomes could be taken as
observational evidence for the phenomenon of crossing
over among linked genes, although he could not prove it.
- Rollins Adams Emerson discovered multiple allelomorphism
in corn and also in beans.
- Svante Arrhenius and Søren Sørensen showed that the
hydrogen ion concentration in a solution could be
experimentally determined. Sørensen pointed out the
effect of pH on enzyme activity.
- Charles Jules Henri Nicolle demonstrated that typhus
fever was transmitted by the body louse.
- Jean Eugene Bataillon discovered the phenomenon of
- James Bryan Herrick discovered sickle cell anemia
- P. Boysen-Jensen established the existence of
phytohormones or auxins which were responsible for the
chemical transmission of growth responses of higher
plants. He demonstrated that the phototropic influence is
material, since it can cross an incision, but cannot pass
through a mica barrier.
- Ivan Petrovitch Pavlov discovered classical conditioning,
and Oskar Heinroth discovered imprinting behavior.
- John Murray and Johan Hjort led the Michael Sars
- Fraser and Stanton showed that alcoholic extracts of rice
polishings had a curative effect in beriberi.
- Sir Henry Hallett Dale studied the properties of
- Paul Ehrlich discovered that solutions of salversan would
selectively kill the organism responsible for syphilis.
- Epstein and Ottenberg pointed out that the human blood
groups (A, B, O) were inherited in accord with Mendelian
- Schlosser conducted further excavations of Oligocene
primate remains from the Fayum.
- Thomas Hunt Morgan proposed a theory of sex-linked
inheritance for the first mutation discovered in Drosophila
melanogaster: white eye. This was followed by the
announcement of the gene theory, including the principle
- Casimir Funk isolated crystalline "antineuritis
vitamine" (actually B-complex) and coined the word
"vitamine" (later changed to vitamin).
- E. B. Harvey studied cortical changes in the egg during
- Hubert Dana Goodale introduced vital staining of the
amphibian embryo as a method of tracing the fate of
- Charles Manning Child formulated his axial gradient
theory of development.
- Richard Benedikt Goldschmidt published the first edition
of his Introduction to the Science of Heredity (Einfürung
in die Vererbungslehre) in which he summarized his
theory of sex determination as a matter of the rate of
developmental expression for sex-determining genes. This
was based on his study of intersexual forms in moths.
- Lucien Claude Cuénot introduced the concept of
- Charles Doolittle Walcott discovered a rich assemblage of
invertebrate fossils from the middle Cambrian in the
Burgess shale of British Columbia.
- Sir Ernest Rutherford posited the existence of atomic
- Alfred Lothar Wegener developed a theory of continental
drift based on fossil and glacial evidence, but his
theory was ridiculed until long after his death because
he could provide no adequate explanation for the cause of
- Carl Neuberg proposed a chemical pathway for
- F. Batelli and L. S. Stern discovered dehydrogenases.
- John Murray and Johan Hjort published The Depths of
- Otto Heinrich Warburg postulated a respiratory enzyme for
the activation of oxygen, discovered its inhibition by
cyanide, and showed the requirement of iron in
- J. F. Gudernatsch found that removal of the thyroid gland
would prevent metamorphosis in frogs, and that feeding
thyroid extracts could induce precocious metamorphosis.
- Edward Albert Sharpey-Schäfer (Schaefer) coined the term
"insuline" for the active principle of the
- G. L. Kite used microsurgical techniques to study the
fine structure of cells.
- Alexis Carrel developed the technique of in vitro
tissue culture. He also developed techniques for
transplantation of organs and an artificial heart.
- Sir William Henry Bragg and Sir William Lawrence Bragg
developed the x-ray crystallography technique which would
later be used in the elucidation of the three-dimensional
structures of proteins and nucleic acids.
- Arthur Smith Woodward announced the discovery of Piltdown
- Jacques Loeb published The Mechanistic Conception of
- Heinrich Otto Wieland showed the activation of hydrogen
in dehydrogenation reactions.
- John Broadus Watson founded the behaviorist school of
psychology, which emphasized the study of observable
behavior rather than conscious and unconscious mental
- Hans Reck discovered rich deposits of early mammalian
fossils including Stone Age artifacts at Olduvai Gorge in
- Leonor Michaelis and Maud L. Menten postulated the
existence of an intermediate enzyme-substrate complex to
explain the mechanism of enzyme action. (Michaelis is
also the father of the home permanent, by virtue of his
discovery of the solubility of keratin in thioglycolic
- Calvin Blackman Bridges reported nondisjunction of sex
chromosomes as a proof of the chromosome theory of
- Alfred Henry Sturtevant developed the first genetic map
by using crossover frequencies as measurements of
- Thomas Burr Osborne and Lafayette Benedict Mendel showed
that rats developed xerophthalmia on diets in which lard
supplied the fat; the condition was cured by substitution
- Shiro Tashiro measured slight increases in carbon dioxide
production in nerves when they were stimulated.
- Publication of Richard Willstätter and Arthur Stoll's Unterschungen
- Victor Ernest Shelford formulated the law of ecologic
- Francis Bertody Sumner studied geographic variation in Peromyscus
and convinced himself that the apparently continuous
variability was actually Mendelian in nature.
- Edward Calvin Kendall completed the final isolation of
crystalline thyroxine, the active substance produced by
the thyroid gland.
- Dr. Joseph Goldberger, of the United States Public Health
Service, demonstrates that pellagra, widely held to be a
hereditary condition, was actually caused by a diet
lacking in meat or milk. The exact cause was later
determined to be niacin deficiency.
- Frank Rattray Lillie hypothesized the existence of a
substance, fertilizin, in the jelly coat of eggs which
causes sperm cells to clump together.
- Warren Harmon Lewis and his wife, Margaret R. Lewis,
- George Harrison Shull demonstrated the phenomenon of
heterosis, commonly referred to as hybrid vigor.
- The Mechanism of Mendelian Heredity, an epochal
book, published by Thomas Hunt Morgan, Alfred Henry
Sturtevant, Calvin Blackman Bridges, and Hermann Joseph
- Frederick Twort discovered a virus capable of infecting
and destroying bacteria.
- Frank Rattray Lillie demonstrates the role of sex
hormones in freemartinism.
- Henry Edward Crampton described geographical races of the
snail Partula in Tahiti.
- Felix Hubert D'Herelle, independently of Frederick Twort,
discovered a virus capable of infecting and destroying
bacteria, which he called a bacteriophage.
- S. Kopec demonstrated the role of the brain in insect
- Ferdinand Broili discovered the fossil remains of Seymouria,
an organism showing both amphibian and reptilian
- Joseph Grinnell introduced the concept of the ecological
- Rollins Adams Emerson discovered and analyzed a highly
mutable gene in maize. After thirty-five years this gene
is still under active study.
- Elmer Verner McCollum and Simmonds showed that
xerophthalmia in rats is due to lack of a fat-soluble
substance which they named vitamin A.
- Richard Benedikt Goldschmidt and L. T. Troland suggested
that genes were enzymes.
- Jacques Loeb introduced the concepts of "forced
movements", "tropisms" and "animal
conduct". He vehemently opposed any anthropomorphic
or teleological interpretations of animal behavior.
- Ernest Henry Starling recognized that the greater the
volume of blood entering the ventricles of the heart, the
greater the force of contraction.
- August Krogh showed that capillaries were capable of
contracting or dilating due to chemical or nervous
- J. S. Szymanski showed that animals were capable of
maintaining 24-hour activity patterns in the absence of
external cues such as light and temperature. These are
now known as "circadian rhythms", or the
- Nikolay Ivanovich Vavilov stressed the importance of
biologic centers of origin as reservoirs of desirable
genes which can be incorporated into cultivated strains
derived from those regions.
- Sir Jack Cecil Drummond named vitamin C, and proposed the
change in spelling from vitamine to vitamin.
- Francis William Aston discovered elements occur in
different isotopes. Rare isotopes have been used as
tracers in the study of biological processes since 1923.
- Sir Edward Mellanby produced experimental rickets in
- Wilbur Willis Swingle reproduced Gudernatsch's results on
metamorphosis in frogs by providing or withholding
- Thomas Hunt Morgan and coworkers published The
Physical Basis of Heredity, a summary of the rapidly
growing findings in genetics.
- A. Paál showed that when the tip of a plant shoot is cut
off and replaced to one side, the growth of the base is
greater on this side.
- Otto Warburg found that the efficiency of photosynthesis
was increased in intermittent light.
- Harry Steenbock demonstrated the relationship between
vitamin A activity and the plant pigment carotene.
- Otto Loewi (Löwi) demonstrated the release of
stimulating and inhibitory substance from terminal
branches of nerve fibers. This discovery led to the
concept of nerve impulse transmission across junctions by
means of chemical mediators or neurotransmitters.
- R. O. Herzog and W. Jancke contributed to the development
of x-ray crystallography.
- H. E. Howard investigated the territorial behavior of
- Hans Spemann described the "organizer" effect
of the amphibian dorsal lip region.
- Thomas Hunt Morgan estimated the gene to have a diameter
of 20-70 microns. Current estimates are considerably
- John Newport Langley functionally distinguished and
described the autonomic nervous system.
- Otto Loewi (Löwi), and, independently, Sir Henry Hallett
Dale, isolated the substance released by the vagus nerve.
Loewi called the substance "Vagusstoff",
but it is now known as acetylcholine.
- Alfred Newton Richards collected and analyzed the
glomerular filtrate of the kidney. His findings were
consistent with the Ludwig-Cushny theory of kidney
- Sir Frederick Gowland Hopkins isolated glutathione from
- Sir Frederick Grant Banting, Charles Herbert Best and
John James Rickard Macleod isolated insulin and further
studied its physiological properties.
- Elmer Verner McCollum et al. showed that experimental
rickets was caused by lack of a new food factor, vitamin
- S. Kopec first demonstrated that pupation in an insect is
conditioned by an agent in the body fluid that originates
in the nervous system. This was the first demonstration
of the hormonal activity of the invertebrate nervous
- Joseph Erlanger and Herbert Spencer Gasser found that the
rates of conduction of mammalian nerve fibers
corresponded to the thickness of their sheaths.
- T. Schjelderup-Ebbe studied social dominance hierarchies
(pecking orders) in birds.
- Leopold Ruzicka recognized isoprene as the building block
of many natural products.
- Otto Warburg reported first measurements on the quantum
efficiency of photosynthesis. Warburg's manometric
apparatus became a standard tool for measuring metabolism
in living cells.
- Johannes Bronsted defined acids as substances which act
as proton sources, and bases as substances which act as
proton acceptors, regardless of the solvent.
- Niels Bjerrum used the strength constants of acids and
bases to study the dissociation of other compounds.
- George Charles de Hevesy first used an isotopic tracer to
study chemical processes in living organisms.
- David Keilin rediscovered histohematins (cytochromes) and
demonstrated changes in their oxidation state during
- Thorsten Ludvig Thunberg first characterized
photosynthesis as an oxidation-reduction reaction in
which carbon dioxide was reduced and water was oxidized.
He also studied the oxidative degradation of foodstuffs
- L. R. Cleveland studied the mutualistic relationship
between termites and their intestinal zooflagellates.
- Robert Feulgen developed a chemical test for
"thymonucleic acid". This reaction is still
widely used to test for DNA.
- Stöhr obtained development of an embryonic heart by
self-differentiation of trunk mesoderm tissue.
- Bernardo Alberto Houssay investigated the role of the
pituitary gland in the regulation of carbohydrate
- Fritz Baltzer discovered that sex determination in some
animals is not chromosomal and that juveniles can be
- Joseph Barcroft demonstrated the spleen's role as a blood
- Vogt constructed maps of the prospective fates of parts
of the amphibian blastula.
- Samuel Ottmar Mast studied the mechanism of amoeboid
movement. This study led to the formulation of many
useful concepts for understanding other protoplasmic
movements, such as cytokinesis. Mast also studied
animals' response to light.
- Hans Molisch obtained the evolution of oxygen by
illuminating preparations of dried leaves.
- George Edward Briggs and John Burdon Sanderson Haldane
made important refinements in the theory of enzyme
- Alfred James Lotka published Elements of Physical
- George Richards Minot and William Parry Murphy discovered
that feeding raw liver had a pronounced effect in the
treatment of pernicious anemia. This discovery led to the
eventual isolation of vitamin B12 and the identification
of yet another vitamin deficiency disease.
- W. Rowan demonstrated the effect of photoperiod on on
birds' physiological readiness for mating and migration.
- Raymond Arthur Dart discovered the "Taung Baby"
fossil, now classified as Australopithecus africanus.
The find was especially significant because it included a
rough cast of the individual's brain.
- G. Koller and E. B. Perkins, by means of blood
transfusions, obtained evidence of the presence of
hormone-like substances regulating the activity of
chromatophores in crustaceans.
- Phoebus Aaron Levene elucidated the structure of
mononucleotides and showed they are the building blocks
of nucleic acids. He also isolated the carbohydrate
portion of nucleic acids and distinguished deoxyribose
- Theodor Svedberg invented the ultracentrifuge and used it
to determine the sedimentation rates of proteins.
- Otto Loewi (Löwi) and Navratil identified the substance
released by the vagus nerve as acetylcholine.
- Kenjiró Fujii observed the coiled structure of the
chromosome for the first time. In certain stages of the
cell cycle, two filaments were seen to be coiled around
- Archibald Vivian Hill used a thermocouple to measure the
heat produced by stimulated nerve fibers. He also showed
that oxygen is consumed in the recovery phase of muscle
contraction and is not directly required for contraction.
- James Batcheller Sumner first crystallized an enzyme,
urease, and proved it to be a protein.
- B. C. P. Jansen and Donath isolated crystalline
thiamin--vitamin B1--from rice polishings.
- Frits Warmolt Went demonstrated that the material
responsible for phototropism (later called auxins) in
plants could diffuse into agar blocks and thus be
collected. He developed quantitative assay methods for
the growth substance.
- Emil Bozler demonstrated that the nerve net of cnidarians
was made up of separate cells connected by synaptic
junctions. He also studied electrical aspects of muscle
contraction and the role of calcium and magnesium in
contraction and relaxation.
- George Ellett Coghill investigated the innate behavior
patterns of salamanders.
- Adolf Otto Reinhold Windaus and others identified
ergosterol as the parent substance of vitamin D.
- Sir Charles Robert Harington synthesized thyroxine.
- Erik Anderson Stensiö reconstructed a fossil Cephalapsid
(an ostracoderm) and suggested its status as a vertebrate
- Karpchenko obtained a tetraploid hybrid between the
cabbage and the radish, thus creating the new species Raphanobrassica.
- Artificial transmutation of the gene was reported by L.
J. Stadler in plants and Hermann Joseph Muller in Drosophila
by means of x-rays.
- Karl Landsteiner discovered the M and N blood groups.
- Theophilus Shickel Painter found a chromosome deficiency
in mice which, along with genetic evidence, provided the
first case of localizing a specific gene to a particular
chromosome in mammals.
- P. Eggleton, G. P. Eggleton, Cyrus Hartwell Fiske and Y.
Subbarow discovered phosphagen in muscle and investigated
its role in contraction.
- Corneille Heymans investigated the role of the carotid
and aortic reflexes in respiratory control.
- W. Garstang theorized that chordates evolved from
organisms resembling ascidians.
- Volhard suggested that a substance in the kidney may be
responsible for some cases of hypertension.
- Fredrick Griffith discovered a "transforming
principle" in pneumococci that was capable of
transforming nonvirulent strains into virulent strains.
- H. von Euler-Chelpin prepared pure carotene and
demonstrated its high vitamin A activity.
- Albert von Szent-Györgyi showed that hexuronic acid was
identical with vitamin C and proposed the name ascorbic
- Sir Alexander Fleming discovered the antibacterial action
- Heinrich Otto Wieland and Adolf Otto Reinhold Windaus
elucidated the structure of the cholesterol molecule.
- Otto Warburg deduced the iron-porphyrin nature of the
- K. Lohmann, Cyrus Hartwell Fiske and Y. Subbarow isolated
ATP and phosphocreatinine from muscle extracts.
- Hans Berger devised equipment to make the first
encephalograms (measurements of brain waves) of human
- Adolf Friedrich Johann Butenandt and Edward Adelbert
Doisy isolated the first sex hormone, estrone, from
- William Bosworth Castle showed that the substance
responsible for preventing pernicious anemia arose from
the combination of an intrinsic factor in the gastric
juice and an extrinsic factor in the diet. This
antianemic factor was then stored in the liver.
- E. Lundsgaard proved that muscles could contract without
lactic acid formation.
- Cornelis Van Niel suggested the parallelism between
photosynthetic processes in bacteria and green plants.
- L. J. Stadler devised and perfected methods for
determining spontaneous mutations rates in maize, finding
that different genes mutate at widely different rates.
- Sewall Wright's studies on the mathematics of
evolutionary changes in populations were published.
- Publication of Ronald Aylmer Fisher's The Genetical
Theory of Natural Selection.
- John Howard Northrop crystallized pepsin and trypsin and
proved their protein nature.
- John Tileston Edsall and A. von Muralt isolated myosin
- V. A. Engelhardt discovered that phosphorylation of ATP
is coupled to respiration.
- Warren Harmon Lewis characterized the process of
- H. B. Creighton and Barbara McClintock demonstrated a
cytological proof for crossing over in maize. A similar
demonstration was made by Curt Stern in Drosophila.
- Sewall Wright presented the first unified picture of
evolution in terms of Mendelism illustrating the
relations between selection pressure, mutation rates.
inbreeding, isolation and the like.
- On the basis of radioactivity and geological data, the
age of the earth was shown to be at least two billion
- K. Lohmann discovered the ATP-phosphocreatinine reaction.
- Otto Warburg and W. Christian isolated a yellow
conjugated flavoprotein from yeast: the yellow enzyme of
- Theodosius Dobzhansky, Theophilus Shickel Painter, and
Hermann Joseph Muller showed that while the seriation of
genes is the same for genetic and cytological maps,
physical distances and crossover map distances did not
- Sewall Wright stressed the importance of "genetic
drift" due to chance in small populations.
- Richard Benedikt Goldschmidt studied adaptation in
geographical races of the Gypsy moth.
- A. Bethe introduces the concept of ectohormones, now
known as pheromones.
- A Danish scientific expedition found ichthyostegid
fossils in Greenland. These are the oldest known fossils
that can be classified as amphibians.
- Edward G. Lewis found the first Ramapithecus, the
earliest known hominid fossil.
- M. Kroll and Ernst August Friedrich Ruska built the first
- N. W. Timofeeff-Ressovsky experimentally measured the
viability of strains of Drosophila funebris of
different geographical origin.
- F. Kögl, Haagen-Smit, and Erxleben isolated auxins and
characterized them chemically.
- Sir Hans Adolf Krebs and K. Henseleit discovered the urea
- R. Collander and H. Bärlund made quantitative
measurements of cell membrane permeability to
nonelectrolytes of varying molecular size and lipid
solubility. Their results contributed enormously to our
understanding of membrane structure.
- Gustav Embden and Otto Meyerhof each demonstrated crucial
intermediates in the chemical pathway of glycolysis and
- David Keilin isolated cytochrome C and reconstituted
electron transport in particulate heart preparations.
- George Wald discovered vitamin A in the retina.
- M. Goldblatt and Ulf Svante von Euler discovered
- Johannes Friedrich Karl Holtfreter produced exogastrulae,
an important tool for understanding embryonic induction.
- John Burdon Sanderson Haldane and Aleksandr Ivanovich
Oparin advanced a heterotroph theory of the origin of
- Theophilus Shickel Painter, Emile Heitz and H. Bauer
recognized the value of Drosophila's giant
salivary chromosomes in genetic analysis. This
facilitated extensive studies on precise gene
localization and chromosome structure.
- Hans Spemann, Joseph Needham, and others showed that
cell-free extracts from the organizer region retained
powers of evocation. Chemical studies of Needham, Conrad
Hal Waddington, and others led to the belief that the
evocator was probably a sterol.
- L'Héritier and Teissier devised the "population
cage" method for the experimental study of natural
- Robert Russell Bensley and N. L. Hoerr isolated and
- Henrik Dam and Edward Adelbert Doisy isolated and
identified vitamin K.
- A. G. Tansley formulates the concept of the ecosystem.
- Francis Bertody Sumner experimentally showed the
selective value of protective coloration in fishes.
- Sven Otto Hörstadius showed the existence of a double
gradient of "animalization" and
"vegetalization" in the echinoderm egg.
- Zimmerman and Wilcoxon discovered several synthetic
substances with hormone activity in plants.
- Wendell Meredith Stanley first crystallized a virus:
tobacco mosaic virus.
- Paul Karrer and Richard Kuhn identified lactoflavin
(riboflavin, or vitamin B2) as the prosthetic group of
Otto Warburg and W. Christian's yellow enzyme.
- Albert von Szent-Györgyi showed the catalytic effect of
dicarboxylic acids on respiration.
- Robert R. Williams and his colleagues deduced the
structure of vitamin B1.
- George Wald suggested that vitamin A is a precursor of
- William Cumming Rose discovered threonine, the last
essential amino acid to have been recognized.
- Rudolf Schoenheimer and David Rittenberg first used
isotopes as tracers in the study of intermediate
metabolism of carbohydrates and lipids.
- H. Davson and James Frederic Danielli proposed a
"protein-lipid sandwich" model for the
structure of cell membranes.
- N. W. Timofeeff-Ressovsky formulated a "target
theory" of gene mutation which says that a mutation
can be induced if a single electron is detached by high
- Edward Calvin Kendall and Phillip Showalter Hench
- L. S. Stern spectroscopically demonstrated the existence
of an intermediate enzyme-substrate complex for the
enzyme catalase, thus confirming the Michaelis-Menten
- Otto Warburg and Hans von Euler-Chelpin isolated
pyrimidine nucleotides and determined their structure and
- Harland Goff Wood and C. Werkman discovered that plant
cells kept in the dark are able to build up larger
organic molecules from carbon dioxide.
- J. Z. Young discovered giant nerve fibers in squid.
- Wendell Meredith Stanley isolated nucleic acid from
tobacco mosaic virus.
- Robert R. Williams and Kline synthesized thiamin.
- Millislav Demerec and M. E. Hoover pointed out the
correspondence between giant salivary gland chromosome
bands and gene maps.
- Publication of Theodosius Dobzhansky's Genetics and
the Origin of Species.
- K. Lohmann and P. Schuster isolated the prosthetic group
from cocarboxylase and showed that it is the diphosphate
of thiamin (vitamin B1).
- Sir Hans Adolf Krebs Krebs and W. A. Johnston postulated
the citric acid cycle.
- Eugen Werle, W. Gotze and A. Keppler discovered kinins.
- Avery, Burkholder and others pursued quantitative studies
on effects of auxins in plant metabolism.
- Kenneth Vivian Thimann suggested that a given
concentration of auxin might produce inhibitory effects
in one tissue and stimulation in another, different
tissues being characterized by a series of overlapping
optimal concentration curves.
- Albert Francis Blakeslee and Avery used colchicine to
produce artificial polyploidy in plant cells.
- P. König and Arne Tiselius developed the technique of
- George William Marshall Findlay and F. O. MacCullum
- Tracy Morton Sonneborn recognized the existence of
different mating types in Paramecium.
- Sir Frederick Charles Bawden discovered that the tobacco
mosaic virus contains RNA.
- Carl Ferdinand Cori and Gerty Theresa Cori began their
incisive studies of glycogen phosphorylase.
- Otto Warburg showed how formation of ATP is coupled to
the dehydrogenation of glyceraldehyde 3-phosphate.
- Herman Moritz Kalckar and Vladimir Aleksandrovitch
Belitser independently carried out the first quantitative
studies of oxidative phosphorylation.
- Van Overbeek reported that certain nongeotropic mutants
in maize did not show the usual inequality of auxin
- Burrhus Frederick Skinner invented the Skinner box, and
used it to investigate operant conditioning in rats.
- Jean Louis Brachet showed that ribonucleic acids are
accumulated in regions of high morphogenetic activity.
- Robin Hill found that cell-free suspensions of
chloroplasts evolve oxygen when illuminated in the
presence of ferric salts.
- A. Braunstein and Kritzman discovered transamination
- William Thomas Astbury and F.O. Bell first used X-ray
crystallography to analyze the structure of DNA.
- Rudolf Schoenheimer applied radioactive tracers to the
study of the biosynthesis of cell structures and
concluded that the body is in a state of dynamic
- Latimeria, a living crossopterygian fish, was
caught off the coast of South Africa. The order
Crossopterygii was believed to have died out in the
Cretaceous period after it gave rise to the amphibian
- Carl Ferdinand Cori and Gerty Theresa Cori demonstrated
the reversible action of glycogen phosphorylase.
- Gregory Goodwin Pincus was able to induce parthenogenesis
in a mammalian egg.
- Sven Otto Hörstadius differentiated eggs into the
categories "regulative" and "mosaic"
depending on their pattern of development.
- Publication of Ernest Everett Just's The Biology of
the Cell Surface.
- Julian Huxley introduces the concept of the cline in
- Ruben, William Zev Hassid and Martin David Kamen first
applied radioactive tracers to the study of
- Borgström found that shoots exposed to ethylene
exhibited positive geotropism associated with the
predicted auxin distribution. Ethylene must in some way
influence the transverse movement of auxin.
- Russel E. Marker developed a method for synthesizing
progesterone in large quantities.
- Fritz Albert Lipmann postulated the central role of ATP
in the energy transfer cycle.
- V.A. Engelhardt and M. N. Lyubimova discovered the ATPase
activity of myosin.
- Albert von Szent-Györgyi discovered actin and actomyosin
and explicated the role of ATP in muscle contraction..
- George Wells Beadle and Edward Lawrie Tatum deduced the
one gene-one enzyme relationship from their work on Neurospora
crassa. Their work profoundly advanced our
understanding of the biochemical effects of mutations.
- Karl Landsteiner and Alexander Solomon Wiener discovered
the Rh blood factor.
- Gaffron showed that algae can utilize molecular hydrogen
- Kausche and Ernst August Friedrich Ruska published first
electron microscope pictures of chloroplasts.
- A. Claude isolated a mitochondrial fraction from liver by
- Ruben, Randall, Martin David Kamen, and Hyde reported
that the oxygen liberated in photosynthesis comes from
- Barry Commoner and Kenneth Vivian Thimann found that
concentrations of 10-5 M of iodoacetate can
halt coleoptile growth but produce no effect on cellular
respiration. They assumed that only a small fraction of
respiration might be involved in growth.
- Carl Ferdinand Cori and Gerty Theresa Cori worked out the
lactic acid metabolic cycle.
- Selman Abraham Waksman coined the term
"antibiotic" to describe compounds produced by
microorganisms which kill bacteria.
- Publication of Charles Manning Child's Patterns and
Problems of Development, an analysis of development
from the viewpoint of the gradient concept.
- Gustaffson and coworkers produced agriculturally superior
new strains of cereals by selection from mutants produced
- Archer John Porter Martin and Richard Laurence Millington
Synge developed partition chromatography and applied it
to amino acid analysis.
- D. McClean and I. M. Rowlands discovered hyaluronidase in
- Konrad Emil Bloch and David Rittenberg discovered that
acetate is the precursor of cholesterol.
- Salvador Edward Luria obtained the first high-quality
electron micrograph of a bacteriophage.
- Reinders found that auxin present in concentrations as
low as 1mg/liter stimulated water uptake in potato discs
along with an increase in respiration and loss in dry
- David Ezra Green and Carl Ferdinand Cori crystallized
- Barry Commoner, Fogel and Detlev Muller demonstrated that
auxin will promote water absorption against an osmotic
gradient. The effect is inhibited by iodoacetate.
- Britton Chance spectroscopically demonstrated the
existence of an enzyme-substrate complex for catalase.
- Severo Ochoa demonstrated the 3:1 phosphorus to oxygen
ratio of oxidative phosphorylation in the citric acid
- Johannes Friedrich Karl Holtfreter demonstrated that
dissociated cells from the same tissue would resynthesize
that tissue if they were kept in contact with each other.
- Joachim Hämmerling demonstrated by a series of
transplantation experiments that the cap morphology of
two related species of the unicellular alga Acetabularia
depends on the species of the nucleus.
- Tracy Morton Sonneborn demonstrated extranuclear
inheritance in Paramecium.
- L. F. Leloir and J. M. Munoz demonstrated fatty acid
oxidation in cell-free liver systems; Albert Lester
Lehninger showed the requirement of ATP and the
stoichiometry of fatty acid oxidation.
- Oswald Avery, Colin MacLeod and Maclyn McCarty
demonstrated that bacterial transformation is caused by
DNA. Some considered this a demonstration that DNA, not
protein, was the hereditary material, but most were not
convinced, owing partly to the cautious tone of the
- Carl Ferdinand Cori demonstrated the effect of insulin on
hexokinase. This was the first demonstration of such a
- Keith Roberts Porter described the structure of the
- Brand reported the first complete amino acid analysis of
a protein, beta-lactoglobulin, by chemical and
- C. Auerbach and J. M. Robson demonstrate chemical
- Joshua Lederberg and Edward Lawrie Tatum studied the
process of conjugation in Escherichia coli.
- Willard Frank Libby developed the carbon-14 dating
- E. I. White discovered a fossil of Jamoytius,
probably the most primitive known chordate.
- Peter Wilhelm Joseph Holtz discovered the hormone
- R. C. Sprigg discovered a rich deposit of Precambrian
fossils in the Ediacara Hills of South Australia.
- Albert von Szent-Györgyi found that neither actin or
myosin was independently capable of contraction. He
coined the term "actomyosin" to describe the
protein complex responsible for muscle contraction.
- Fritz Albert Lipmann and Kaplan isolated and chemically
characterized coenzyme A.
- L. F. Leloir and his colleagues discovered the role of
uridine nucleotides in carbohydrate metabolism.
- Karl von Frisch studied communication in honeybees.
- Walter Rudolf Hess perfected a method of implanting
electrodes in the brains of rats and was able to localize
centers of the brain associated with certain instincts.
- G. H. Hogeboom, Walter Carl Schneider, and George Emil
Palade refined the differential centrifugation method for
cell fractionation and used it to isolate mitochondria.
- Benjamin Minge Duggar discovered aureomicin, the first
- Melvin Calvin and Benson reported that the major
intermediate compound in which carbon is fixed in
photosynthesis is phosphoglyceric acid.
- Eugene Patrick Kennedy and Albert Lester Lehninger
discovered that the citric acid cycle, fatty acid
oxidation, and oxidative phosphorylation take place in
- Christian René de Duve discovered the lysosome.
- William Howard Stein and Stanford Moore reported the
complete amino acid analysis of beta-lactoglobulin,
determined by starch column partition chromatography.
- John Franklin Enders and Frederick Chapman Robbins and
Thomas Huckle Weller found that animal viruses could be
grown in cell culture instead of live animals.
- Ulf Svante von Euler studied the role of norepinephrine
as a sympathetic neurotransmitter.
- Linus Carl Pauling showed that sickle cell hemoglobin
showed different electrophoretic properties than normal
hemoglobin. This demonstrated that genetic mutations lead
to specific chemical changes in protein molecules.
- Hans Selye developed the concept of the stress syndrome
after a twelve year study of the physiological effects of
stress on animals.
- Frederick Sanger developed the 2,4-dinitrofluorobenzine
method and Edman developed the phenylisothiocyanate
procedure for identification of the N-terminal residues
- H. G. Callan and S. G. Tomlin described the structure of
the nuclear membrane as a double membrane with pores.
- Tobjörn Oskar Caspersson and Jean Louis Brachet studied
the role of RNA in protein synthesis.
- Linus Carl Pauling and R. B. Corey proposed the
alpha-helix structure for alpha-keratin.
- M. Simpson and Choh Hao Li point out that hormonal
coordination is necessary for the balanced development of
- Konrad Lorenz establishes the discipline of ethology.
- Erwin Chargaff and coworkers discovered base
equivalencies in DNA: the amount of purines always equals
the amount of pyrimidines, the amount of adenine always
equals the amount of thymine and the amount of guanine
always equals the amount of cytosine.
- Edward B. Lewis introduced the notion of pseudoallelism.
- Carl Djerassi, following the methods of Russel E. Marker,
synthesized 19-Norsteroids, a powerful synthetic
- John Rock, Gregory Goodwin Pincus and Min Chuch Chang
discover that 19-Norsteroids prevents ovulation in women.
- Albert Lester Lehninger showed that electron transport
from NADH to oxygen is the immediate energy source for
- Feodor Lynen postulated the role of coenzyme A in fatty
- The laboratories of Feodor Lynen, David Ezra Green, and
Severo Ochoa isolated the enzymes of fatty acid
- Alfred Day Hershey and Martha Chase proved, on the basis
of their bacteriophage research, that DNA alone carries
- Norton David Zinder and Joshua Lederberg discovered
transduction: bacterial DNA can be carried from one
bacterium to another by a bacteriophage virus.
- W. Beerman associated chromosomal puffs with gene
- Jean Louis Brachet suggested that movements of microsomes
(which contain ribonucleic acid) from the archenteron
roof to the overlying ectoderm are involved in neural
- Robert William Briggs and T. J. King demonstrated an
apparent developmental differentiation in nuclear
- Gustav Kramer demonstrates sun-compass orientation in
- George Emil Palade, Keith Roberts Porter, and Fritiof
Stig Sjöstrand perfected thin sectioning and fixation
methods for electron microscopy of intracellular
structures, especially of mitochondria.
- Rosalind Franklin produced precise X-ray diffraction
images of the B form of DNA.
- Paul Charles Zamecnik and his colleagues discovered that
ribonucleoprotein particles, later named ribosomes, are
the site of protein synthesis.
- George Emil Palade described ribosomes.
- James Dewey Watson and Francis Harry Compton Crick
accurately described the molecular structure of DNA.
- Frederick Sanger, E. O. P. Thompson and Hans Tuppy
completed the determination of the amino acid sequence of
the A and B chains of insulin.
- Bernard Leonard Horecker, Dickens, and Efraim Racker
elucidated the 6-phosphogluconate pathway of glucose
- André Michael Lwoff found that bacteriophage viruses
were capable of inserting their genome into the host
genome. A virus in this condition is known as a prophage.
- Harold Clayton Urey and Stanley Lloyd Miller found that
several amino acids were formed when ammonia, methane,
water vapor and hydrogen were exposed to an electrical
discharge for several days. This suggested a possible
scenario for the origin of life on the primitive earth.
- Vincent du Vigneaud carried out the first laboratory
synthesis of the peptide hormones oxytocin and
- Bernard Katz described impulse transmission across a
- Hugh Esmore Huxley, Jean Hanson R. Niedergerde, and
Andrew Fielding Huxley formulated the sliding filament
theory of muscle contraction.
- Daniel I. Arnon and colleagues discovered photosynthetic
- Britton Chance and G. R. Williams applied the oxygen
electrode and difference spectrophotometry to the study
of the dynamics of electron transport in mitochondria.
- Revised estimates put the age of the earth at five to six
- J. C. Dan described the acrosome reaction in sperm.
- E. P. Kennedy described the pathway of biosynthesis of
triacylglycerols and phosphoglycerides and the role of
- Frederick Sanger and his colleagues reported the position
of the disulfide cross-linkages between the A and B
chains of insulin.
- Seymour Benzer carried out fine-structure genetic mapping
and concluded that a gene has many mutable sites.
- Severo Ochoa and M. Grunberg-Manago discovered
polynucleotide phosphorylase and successfully synthesized
- Heinz Fraenkel-Conrat and Robley Cook Williams separated
TMV nucleic acid from its protein coat and found that
both were necessary for infection.
- H. D. B. Kettlewell demonstrated the effects of natural
selection on melanic and mottled forms of Biston
betularia in two different environments.
- Arthur Kornberg discovered DNA polymerase.
- H. Borsook and Paul Charles Zamecnik found the ribosomes
of the endoplasmic reticulum to be the site of protein
- H. E. Umbarger reported that the end product isoleucine
inhibits the first enzyme in its biosynthesis from
threonine. Yates and Pardee reported the feedback
inhibition of aspartate transcarbamoylase by cytidine
- Christian Boehmer Anfinsen and White concluded that the
three-dimensional conformation of proteins is specified
by their amino acid sequence.
- William Stanley Peart and D. F. Eliot isolated
- E. W. Sutherland and T. W. Rall discovered cyclic AMP.
- Joe-Hin Tjio and Johan Albert Levan revised Walther
Flemming's 1898 estimate of the human chromosome count
from 24 pairs to 23 pairs.
- George von Békésy's traveling wave theory of hearing
replaces the resonance theory.
- Vernon Martin Ingram showed that normal and sickle-cell
hemoglobin differ in a single amino acid residue in one
of the chains.
- Vogel, Magasanik, and others described genetic repression
of enzyme synthesis.
- Seymour Benzer introduced the concept of the cistron: the
smallest unit of function of the gene.
- E. W. Sutherland discovered cyclic adenylic acid.
- Mahlon Bush Hoagland, Paul Charles Zamecnik, and M.L
Stephenson isolated transfer RNA and postulated its
- J. C. Skou discovered Na+ K+-stimulated
ATPase and postulated its role in the transport of Na+
and K+ across the cell membrane.
- John Cowdery Kendrew elucidated the three-dimensional
structure of myoglobin.
- Melvin Calvin and his coworkers completed a step by step
analysis of the reactions involved in the synthesis of
carbohydrates in plants.
- F. Sauer used a planetarium to study stellar navigation
- R. W. Holley explicated the role of transfer RNA in
- James Herbert Taylor, Philip Sargent Woods, and W. L.
Hughes demonstrated semiconservative replication in DNA
using 3H and autoradiography.
- Matthew Messelson and Franklin Stahl demonstrated
semiconservative replication in DNA using 15N
and ultracentrifugation in a density gradient.
- Francis Harry Compton Crick enunciated the central dogma
of molecular genetics: information flows from DNA to RNA
- William Howard Stein, Stanford Moore, and Spackman
devised the automatic amino acid analyzer, which greatly
accelerated the analysis of proteins.
- Samuel Bernard Weiss, J. Hurwitz and others discovered
the DNA-directed RNA polymerase.
- Sir Frank Mcfarlane Burnet formulated the clonal
selection theory of immunity.
- C. E. Ford, P. E. Jacobs and Joe-Hin Tjio elucidated the
chromosomal basis of sex determination in humans.
- Jerome Jean Louis Marie LeJeune, M. Gautier and Raymond
Alexandre Turpin discovered an extra chromosome in the
nuclei of cells obtained from children with Down's
- Max Perutz elucidated the three-dimensional structure of
- Mary Leaky discovered the Zinjanthropus boisei
fossil, now considered to be an ultrarobust
- Adolf Friedrich Johann Butenandt isolated and chemically
analyzed for the first time a pheromone: bombykol, the
sex attractant of the silk moth.
- R. Yalow and Solomon Aaron Berson developed the
- John Cowdery Kendrew reported the high-resolution x-ray
analysis of the three-dimensional structure of sperm
- François Jacob and Jacques Lucien Monod proposed the
operon hypothesis for the regulation of enzyme synthesis.
- Hirs, Stanford Moore, and William Howard Stein determined
the amino acid sequence of ribonuclease; Christian
Boehmer Anfinsen made important independent
- Robert Burns Woodward synthesized chlorophyll a.
- Elwyn LaVerne Simons conducted the most extensive
excavations ever undertaken on the Oligocine formation of
the Fayum, contributing enormously to our knowledge of
the early development of the higher primates.
- François Jacob, Jacques Lucien Monod, and Jean-Pierre
Changeux proposed a theory of the function and action of
- Jacques Francis Albert Pierre Miller elucidated the role
of the thymus gland in the development of immunity.
- François Jacob and Jacques Lucien Monod postulated the
function of messenger RNA.
- Peter Mitchell postulated the chemiosmotic hypothesis for
the mechanism of oxidative and photosynthetic
- Marshall Warren Nirenberg and J. Heinrich Matthaei
reported that polyuridylic acid codes for
polyphenylalanine and thus opened the way to
identification of the genetic code.
- Robert Palese Perry found that messenger and transfer RNA
are synthesized on the chromosomes, and ribosomal RNA is
synthesized in the nucleolus.
- The laboratories of Robert William Holley, Marshall
Warren Nirenberg, Har Gobind Khorana and Severo Ochoa
identified the genetic code words for the amino acids.
- Efraim Racker and his colleagues isolated F1 ATPase from
mitochondria and subsequently reconstituted oxidative
phosphorylation in submitochondrial vesicles.
- Douglas Harold Copp discovered calcitonin.
- William Donald Hamilton proposed a process of kin
selection to explain the selective advantage of neuter
castes in the social insects.
- Bill Henriksen Hoyer, Brian John McCarthy and Ellis
Truesdale Bolton pointed out that similarities in
polynucleotide sequences in different species's DNA could
be used as a measurement of phylogenetic proximity.
- Genes conveying resistance to antibiotics in bacteria
were found to reside on small, supernumerary chromosomes
- The Endangered Species Act is created.
- Mark Ptashne isolated the first repressor protein.
- Bernard Weiss and Charles Clifton Richardson isolated and
studied a polynucleotide (DNA) ligase from E. coli.
- W.M. Fitch and E. Margoliash calculated the phylogenetic
relationships of twenty organisms, ranging from fungi to
mammals, by comparing their cytochrome C amino acid
- Robert H. MacArthur and Edward Osborne Wilson establish
the discipline of theoretical ecology.
- Jane van Lawick-Goodall studied the social behavior of
- Gerald M. Edelman and R.R. Porter elucidated the
structure of gamma globulin.
- Howard Martin Temin and David Baltimore independently
discovered retroviruses: RNA viruses capable of reverse
transcription: synthesizing DNA from an RNA template.
- The first restriction enzyme was isolated.
- Lynn Margulis proposed an endosymbiont theory for the
origins of eucaryotic organelles.
- Robert Burns Woodward and Albert Eschenmoser synthesized
- Seymour Jonathan Singer and Garth L. Nicolson proposed a
fluid-mosaic model for the structure of cell membranes.
- Workers at Stanford University construct the first
recombinant DNA molecules using restriction enzymes and
- Stanley Norman Cohen and Herbert Wayne Boyer demonstrated
that restriction enzymes could be used to transfer genes
from one species to another. Recombinant DNA plasmids
were successfully implanted in Escherischia coli
cells, thus demonstrating the possibility of cloning
foreign genes in bacterial cells.
- The Endangered Species Act was extended and strengthened.
- Public concern arose over the possibility of the
production of potentially dangerous microorganisms by
recombinant DNA technology.
- Critics of recombinant DNA technology called for a
worldwide moratorium on certain classes of recombinant
- A government report in the United Kingdom called for
special laboratory precautions to be employed in
recombinant DNA research.
- An international conference was convened in Asilomar,
California which urged strict guidelines regulating
recombinant DNA research.
- Edward Osborne Wilson's Sociobiology published.
- Joseph William Sanger found that actin and myosin were
responsible for the movement of chromosomes on their
- Albert Schmitz, Ursula Schmeissner, Jeffrey H. Miller and
Ponzy Lu altered the amino acid composition of the lac
repressor protein to determine which amino acids are
necessary for the various functions of the complete
- The National Institutes of Health published their first
guidelines restricting many categories of recombinant DNA
- Genentech, the first genetic engineering company, is
founded to use recombinant DNA methods to produce
medically important drugs.
- The first recombinant DNA molecules incorporating
mammalian DNA were produced. Split genes were discovered.
- Procedures were developed for rapidly sequencing long
sections of DNA.
- Smallpox was eradicated worldwide.
- The Nobel Prize in Medicine was awarded for the discovery
and use of restriction enzymes.
- Somatostatin was produced using recombinant DNA methods.
- The NIH guidelines were relaxed, permitting the study of
viral DNAs using recombinant DNA procedures.
- DNA from malignant cells was used to transform cultured
mouse cells, permitting cancer genes to be studied in
- Construction was begun on the first industrial plant
designed to make insulin using recombinant DNA methods.
- The Nobel Prize in Chemistry was awarded for the creation
of the first recombinant DNA molecules and the
development of powerful DNA sequencing methods.
- Genentech offers stock in the company for sale to the
general public. Valuation by Wall Street was in excess of
- Gene cloning experiments using laboratory strains of Escherischia
coli and yeast as hosts for propagation of
recombinant DNA were exempted from the NIH guidelines.
- Sickle cell anemia became the first genetic illness to be
diagnosed antenatally directly at the gene level, by
restriction enzyme analysis of the DNA.
- Despite further wholesale relaxations of the NIH
guidelines, a move to make compliance voluntary failed.
- Cloned rat growth hormone genes were injected into mouse
zygotes, producing "supermice" that were twice
the normal weight.
- Human insulin produced by recombinant DNA methods was
marketed under the name Humulin.
- A foreign gene incorporated into the cells of a tobacco
plant was shown to be transmitted in ordinary Mendelian
fashion through the gametes.
- A human cancer gene, isolated from bladder cancer cells,
is cloned in Escherischia coli. The base sequence
of the cancer gene is found to differ from the same locus
in a normal cell by a single base pair which causes a
substitution of an amino acid in the resulting protein.
- An entirely new syndrome, characterized by severe
impairment of the immune system, is recognized and given
the name acquired immunodeficiency syndrome or AIDS.
- The complete 48,502 base pair sequence of the DNA of
bacteriophage lambda is published.
- Kary B. Mullis invents the polymerase chain reaction
(PCR), a method for rapidly and easily cloning DNA
- César Milstein, Georges J.F. Kohler, and Niels Kai Jerne
are awarded the Nobel Prize for their work in developing
techniques for producing monoclonal antibodies.
- Susumu Tonegawa wins the Nobel Prize for his work in the
genetic mechanisms of antibody production.
- Kary B. Mullis is awarded the Nobel Prize for the
polymerase chain reaction.
- Michael Smith is awarded the Nobel Prize for his
discovery of site-directed mutagenesis.
- Allen, Garland E. Life Science in the Twentieth
Century. New York: Cambridge University Press, 1978.
- Debus, Allen G., et al., eds. World Who's Who
in Science. Chicago: Marquis, 1968.
- Doke, Tatsumasa. "The Controversy Between Liebig and
Pasteur." Japanese Studies in the History of
Science 6 (1967): 87-95.
- Doke, Tatsumasa. "The Controversy Between J. Liebig
and L. Pasteur." Actes (XIIe)
Congrés International D'Histoire Des Sciences Tome
VIII (1968): 31-39.
- Gabriel, M.L., and S. Fogel, eds. Great Experiments in
Biology. Englewood Cliffs: Prentice-Hall, 1955.
- Hickman, C.P.Jr., L.S. Roberts and F.M. Hickman. Integrated
Principles of Zoology, 7th ed. St. Louis: Mosby,
- Keeton, William T., J.L. Gould and C.G. Gould. Biological
Science. New York: Norton, 1986.
- Kohler, Robert E. "The Background to Eduard
Buchner's Discovery of Cell-Free Fermentation." Journal
of the History of Biology 4 (1) (Spring 1971): 35-61.
- Kohler, Robert E. "The Reception of Eduard Buchner's
Discovery of Cell-Free Fermentation." Journal of
the History of Biology 5 (2) (Fall 1972): 327-353.
- Lehninger, Albert L. Biochemistry, second edition.
New York: Worth Publishers, 1975.
- Maurer, James F., et al., eds. Concise
Dictionary of Scientific Biography. New York:
- Moore, John A. Science as a Way of Knowing: The
Foundations of Modern Biology. Cambridge: Harvard
University Press, 1993.
- Nordenskiöld, Erik The History of Biology. New
York: Tudor Publishing, 1936.
- Parkinson, Claire L. Breakthroughs: a chronology of
great achievements in science and mathematics, 1200-1930.
Boston: G.K. Hall, 1985.
- Sirks, M. J. and C. Zirkle. The Evolution of Biology.
New York: Ronald Press, 1964.
- Watson, J.D., J. Tooze, and D.T. Kurtz. Recombinant
DNA. New York: Scientific American Books, 1983.
Peter v. Sengbusch - firstname.lastname@example.org