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These pages represent a biased choice of dates relevant to biology, obtained by compiling a great many different sources, often using the original texts and not the WWW; the information collected here does not use Wikipedia which, by construction, relies on a process akin to a vote, and changes over time in order to reflect some kind of a popular consensus about knowledge rather than accurate knowledge. Care has been taken to check information and rewrite it when needed; direct access links to the original sources is provided whenever possible; however date records still contain many errors; the links are chosen to be as diverse as possible, they do not engage the responsability of the author. Note however that many WWW links are generally unstable, so that many might be obsolete despite regular checks.

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ca 1800 In his lectures, Karl Friedrich Kielmayer (1765 - 1844), a teacher of Cuvier in Stuttgart who never allowed publication of any of his work, places emphasis on the comparative study of organs.

1800 Alessandro Volta (Como 1745 - Pavia 1827) invents the wet cell battery aptly named a "pila". He is made "Comte" by Napoléon for this invention a year later.

1800-1804 Nicolas Thomas Baudin (Ile de Ré, France, 1754 - Ile Maurice, 1803) commands a French scientific, strategic and economic expedition to New Holland (Terra Australis: Australia) associating the corvette Galatée, renamed Le Géographe and the much slower storeship Ménacarte renamed Le Naturaliste. More than a dozen scientists were on board , when leaving France but several investigators and crews deserted at the first stop at Ile-de-France (Mauritius). After exploring the west of Terra Australis during the winter 1801, the expedition goes north to Timor, then south to Tasmania. Because of their large difference in speed the ships separate, while Le Géographe meets the English exploring ship Investigator, commanded by Matthew Flinders and in the winter of 1802 reaches the English penal colony in Port Jackson. Le Naturaliste is sent back to France in November 1802 with all collections made so far. Thereafter Le Géographe continues together with the locally built Casuarina along the south Australian coast, reaching King George Sound in February 1803 and Timor in May, where the only left botanist stays until 1807 because of illness. In September 1803 Baudin dies at Ile de France and the Casuarina is abandoned there. In March 1804 Le Géographe reaches France with the collections made after that Le Naturaliste had left Australia.

1801 Lamarck uses the term "biologie" (from the Greek βιος, life, and λογος, law, reason) to denote the study of living organisms in his work Hydrogéologie. He is among the last scientists to see life within the frame of pre-atomic physics. This explains much of the misunderstandings about his way to see evolution.

1801 Napoléon meets the rebellion of François Dominique Toussaint Louverture (Bréda ca 1743 - Fort de Joux 1803) in the Carribean, and 27,000 soldiers under General Charles LeClerc die there of Yellow Fever. This decides of the selling of Louisiana to the United States of America.

1801 Marie François-Xavier Bichat (Thoirette 1771 - Lyon 1802) publishes his Traité d'anatomie descriptive. Despite his young age he introduces a new system into the science of anatomy. Assuming that the true essence of life is inaccessible, he states that one has to study it through the phenomena it manifests, either normal or pathological. He insists on the importance of structure, which he makes a corner-stone of biology. He distinguishes twenty one types of tissues: cellular (connective tissue), nervous tissue, arterial, venous, the exhalation tissue, absorbent, bone tissue, medullary tissue (in the bones), cartilaginous, fibrous, fibrocartilaginous, animal muscle, organic muscle, mucous tissue, serous tissue, synovial tissue, glandular, dermoid, epidermoid and finally capillary. In his work he makes experiments to distinguish between organic sensibility (receiving an impression) and animal sensibility (which in addition conveys the impression to a common centre).

1801 Jean-Antoine Claude Chaptal (Nogaret, Lozère, 1756 - Paris, 1832) after having improved the production of sugar by beet roots, publishes the Art de faire, de gouverner, et de perfectionner les vins, where he invents the process now named "chaptalization" meant to enhance the alcoholic degree of wine by sugar addition.

1801-1814 Leopoldo Marco Antonio Caldani (Bologna, 1725 - Padova, 1813) and his nephew Floriano Caldani publish a monumental illustrated reference work on human anatomy, Icones anatomicae quotquot sunt celebriores ex optimis neotericorum operibus summa diligentia depromptae et collectae; Iconum anatomicarum explicatio.

1802 Lamarck, who had started his career at the age of fifty, nominated by the French Revolution National Convention at the Jardin des Plantes, as a zoologist specialist of invertebrates (although he had mostly be interested in plants) elaborates a theory of evolution based on heritable modification of organs through continued use and loss through disuse, which he publishes in his Recherches sur l'organisation des corps vivants. There, basing his theory on the analysis of the progression of organ structures in different species, he states that it is important to consider not individuals, but classes (following Vicq d'Azyr) and states that it is not the organs which have given rise to the habits of animals, but the habits and manners of life which have fashioned the body forms (hence visible variations in populations, and progressive variations in different species). This is of course exactly the opposite of what could be found in ancient atomist theories (for example in Lucretius De Rerum Natura), as well as in the work of Empedocles. The active principle of modification is the "feu éthéré" which gives an "orgasme vital", a state of tension, a "tonus" which maintains all parts of the body in a given (moving) shape. This fire is transmitted upon fertilization from the male sexual product to the embryo. This fire exists everywhere in Nature, and is therefore the cause of the spontaneous generation of life... This shows that Lamarck thought is deeply impregneted by the theory of the four elements, not yet influenced by the renewal of the atomist theory, with the new chemistry of Lavoisier.

1802 Pierre Jean Georges Cabanis (Cosnac 1757 - Rueil-Malmaison 1808) repeatedly states (Rapports du physique et du moral de l'Homme), as did Locke and Condillac, that all ideas are based on sense-impressions.

1802 Bichat dies from a malignant fever at a time when his Traité des membranes is published.

1802 Thomas Young (Milverton 1773 - London 1829) proposes a trichromatic theory of color vision, based on three separate receptor substances in the retina.

1802 Charles François Brisseau de Mirbel (1776 - 1854) professor of Botany at the Jardin des Plantes in Paris, concludes from his microscopic observations of plants that the plant is wholly formed of a continuous cellular membranous tissue.

1802-1822 In parallel with Lamarck, Gottfried Reinhold Treviranus (1776-1837)'s monumental Biologie oder Philosophie de Lebended Natur, speads the word biology. Treviranus introduced the notion of biology as a distinct discipline into Germany and was one of the first to express the idea that the cell is the structural unit of living matter.

1803 Claude Louis Berthollet (Talloires 1748 - Arcueil 1822) publishes his Essai de statique chimique. With Fourcroy and Guyton de Morveau (Dijon 1737 - Paris 1816), he had followed the lessons of Lavoisier, and had improved the technique of dying. He also established the composition of prussic acid (hydrogen cyanide) and of hydrogen sulfide. He discovered sodium hypochlorite and potassium chlorate.

1803 The discovery of iridium (named after Iris, goddess of the rainbow, because of the variegated colour of its salts) and osmium (from the Greek word for "odour," because of the chlorine-like odour of its volatile oxide), later used for electron microscopy is claimed by the English chemist Smithson Tennant (1761-1815). The French chemists Hippolyte-Victor Collet-Descotils (Caen, 1773 - 1815), Antoine François de Fourcroy (Paris, 1755 - 1809), and Nicolas Louis Vauquelin (Saint-André-d’Hébertot 1763 - 1829) identify the two metals at about the same time.

1804 Nicolas Théodore de Saussure (Genève 1767 - 1845) publishes in his Recherches chimiques sur la végétation, experiments that represent the first treatment of the subject of photosynthesis using quantitative methods and modern chemical terminology. He develops there the first balanced equation for the process.

1804 Building on the work of Proust, John Dalton (Manchester 1766 -1844) enunciates his atomic theory (hence the mass unit created after his name, the Dalton, mass of the hydrogen atom).

1804 Giovanni Aldini (Bologna, 1762 - Milano; 1834) dedicates to Bonaparte his "Essai théorique et expérimental sur le galvanisme, avec une série d'expériences faites en présence des commissaires de l'Institut National de France, et en divers théâtres anatomiques de Londres". This work relates experiments on a hanged man in London, and in Calais on work demonstrating galvanism across the sea. The effects of galvanism on the animal system, the velocity of electricity through water, electrical fishes and the conductivity of flames are explored.

1805 Father of preventive medicine, Parmentier imposes vaccination for Napoléon soldiers.

1805 Friedrich Wilhelm Adam Serturner (1784-1841) isolates from opium a substance he called morphine (after Morpheus, the Greek God of sleep).

1805 Georges Cuvier publishes the last of his "Leçons sur l'Anatomie Comparée", which, although much influenced by his predecessors — Daubenton and chiefly Vicq d'Azyr — introduce that subject. In this work he acknowledge the importance of the new chemistry and enumerates the atoms of the body: carbon, hydrogen, oxygen and nitrogen, pointing out the major importance of the latter in animals, as compared to plants. The correlation between the separate organs in the same body, that Vicq d'Azyr had already described in its main features is studied in details by Cuvier, and to him represents the very basis of his conception.

1805 Alexandre Brongniart (Paris 1770-1847)'s "Essai d'une Classification Naturelle des Reptiles", started in 1800, and which provides a new way to class these animals, is not published in full until 1803. It appears in the volume of the Mémoires presentés à l'Institut par divers Savans for 1805.

1805 Ludolf Christian Treviranus (1779-1864) proposes that spermatozoa play a role analogous to that of the pollen of plants.

1806 Jean Nicolas de Corvisart des Marets (1755-1821) translates von Augenbrugg work on chest percussion and establishes general principles of cardiology (Essais sur les maladies du coeur et des gros vaisseaux).

1806 Vauquelin and Pierre Jean Robiquet (1780 - 1840) isolate the first amino-acid, asparagine, from asparagus.

1806-1808 Jöns Jacob Berzelius (Väversunda 1779 - Stockholm 1848), known as one of the creators of chemistry, expounds in his Lectures on Animal Chemistry that life does not lie in any extraneous essence deposited in an organic or living body, but must be sought in the common fundamental forces of primal elements.

1807 Isaac Bénédict Prévost (Genève, 1755 – 1819) shows that an organism is responsible for wheat bunt disease and that copper salts can prevent the disease.

1807 François Péron (Cerilly, 1775 - 1810) and Charles-Alexandre LeSueur (Le Havre, 1778 - Le Havre, 1846) who had joined Baudin's expedition to New Holland in charge of works as diverse as anatomy, anthropology, botany, zoology, meteorology, oceanography and naval hygiene publish the first volume of Voyage de découvertes aux Terres Australes. Together they collect more than 100,000 zoological specimens (including many live species).

1807 Jean Baptiste Joseph Fourier (Auxerre 1768 - Paris 1830) was nominated in 1794 to study in Paris, at the Ecole Normale which opened in January 1795. He was taught there by Lagrange, Laplace and Monge. While in Egypt with Napoleon, Fourier helped found the Cairo Institute. In 1807 he submits a memoir on the cooling of infinite solids and terrestrial and radiant heat, later used by Lord Kelvin to calculate the age of the Earth.

1808 In his Exposition et défense de ma théorie végétale Mirbel shows that plants consist of cells, whose parts are continuous and form a single membranous fabric. He states that the cellular nature is the basis of all structures in the plant kingdom, thus predating the cell theory that was about to be born.

1808 Franz Joseph Gall (Baden 1758 - Paris 1828) in his Recherches sur le Système nerveux publishes the first work on the science of the shape of the skull (cranioscopy, later known as phrenology).

1809 Reil uses alcohol to preserve the brain by hardening.

1809 Lamarck investigates the microscopic structure of plants and animals. He remarks that 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. Lamarck's Philosophie Zoologique reviews the animal system and emphasizes the fundamental unity of life and the capacity of species to vary under environmental influences dominated by stressing conditions. Lamarck draws up the invertebrate system where he distinguishes Infusoria from the Polypi, and the Cirripedia from the Mollusca, getting ten invertebrate classes, most of which are still retained today: Infusoria, Polypi, Radiata, Vermes, Insecta, Arachnida, Crustacea, Annelida, Cirripedia and Mollusca.

1809 Appert, the French chef, completes his experiments demonstrating a procedure for preservation of foods by canning.

1809 Lorenz (Okenfuss) Oken (1779 - 1851) publishes his Naturphilosophie, where he extends the romantic imaginative description of life. His theories were reserved to a cultural elite and were supposed to be unattainable for the majority (this is reminiscent of Pythagoras). Oken created the journal Isis and founded theosophy which became a focus for "scientific" life in Germany.

1809 Luigi Rolando (Torino, 1773 - 1831) works on the brain of birds and uses galvanic current to stimulate the cortex.

1810 William Hyde Wollaston (East Dereham 1766 - London 1828) known for his discovery of rhodium and palladium, isolates the second amino-acid, cystine, from a bladder stone.

1810 Christian Friedrich Samuel Hahnemann (Meissen, Germany, 1855 - Paris, 1843) publishes a book Organon der Heilkunst (Organon of the Healing Art) that had to have a considerable commercial influence through the creation of a whole field of paramedical practices. Based on the pre-scientific concept of cure: "similia similibus curantur" (or like is cured by like), Hahnemann creates homeopathy (from the Greek ὁμοιος, same and παθος, suffering). It is interesting to note that this approach has spread throughout the world despite its conflict with the observations and concepts of physics and chemistry (existence of atoms). This is because, in spite of negative conclusions established from the outset, the approach is both harmless as such (it can be dangerous because it involves the failure to help a person in danger, if there exists an treatment that works) and very lucrative.

1810 Joseph Louis Gay-Lussac (Saint Léonard de Noblat 1778 - Paris 1850) deduces the equation for alcoholic fermentation C₆H₁₂O₆ --> 2 C₂H₅OH + 2 CO₂.

1811 The pharmacist and chemist Henri Braconnot (Commercy 1780 - Nancy 1855) isolates from mushrooms a compound that will be identified from insects in the 1830s, and will be called chitin.

1811 César Julien Jean LeGallois (1770-1840?) discovers respiratory center in the medulla. LeGallois considers the feasibility of artificial circulation.

1811 Lorenzo Romano Amedeo Carlo Avogadro (Torino 1776 - 1856) proposes in the Journal de Physique 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.

1811 Charles Bell (Edinburgh 1774 - London 1842) in his Idea of a New Anatomy of the Brain and François Magendie (Bordeaux 1785 -Sannois 1855) in his numerous lectures and publications discover the functions of the dorsal and ventral roots of spinal cord. Magendie worked on live animals, which was perceived with horror by some of his contemporaries. Magendie strongly opposes Bichat's vitalism. In general he considers hypotheses as useless, facts alone having any scientific value.

1812 Georges Cuvier's important study Recherches sur les ossemens fossiles des quadrupèdes [Research on the Fossil Bones of Quadrupeds] is first published.

1813 Augustin Pyrame de Candolle (Genève 1778 - 1841) publishes his Théorie élémentaire de la botanique in which he states that life is dominated by four great forces: attraction and affinity, which are at the root of the physico-chemical properties of life, and life-force and sensibility, which are specific to life, the latter being restricted to animals. He repudiates Lamarck's hypothesis of a single evolutionary chain of organisms. He defines a species by the collection of all the individuals which resemble more each other than others, are capable of mutual fertilization producing fertile individuals and are multiplied by generation so that it is reasonable by analogy to assume that they descend from one single individual. In this work he uses the suffix "-blaste" to describe part of the plant embryo. This suffix will subsequently be used generally.

1814 André-Marie Ampère (1775 - 1836), independently of Avogadro, discovers the same concept that a fixed number of molecules of any gas will equal the molecular weight of the gas in grams, that he publishes in the Annales de Chimie, together with a breakthrough of prime importance: molecules are represented as simple polyhedra in which atoms occupy the corners, the polyhedron representing "la forme représentative de la particule" (the representative shape of the molecule).

1814 Saussure quantifies alcoholic fermentation.

1814 René Joachim Henri Dutrochet (Néon 1776 - Paris 1847) publishes his investigations into animal development, suggesting a unity of the main features during the early stages. Later research into plant and animal physiology allows him to state that respiration is similar in both plants and animals.

1815 Konstantin Sigizmundovich (Gottlieb) Kirchhof (Teterow 1764 - 1833), who had discovered glucose, reports, after having chemically hydrolyzed starch, that a glutinous component of wheat is also capable of converting starch to dextrin and sugar.

1815 Lamarck publishes his Histoire naturelle des animaux sans vertèbres.

1815 Jean-Baptiste Biot (Paris 1774 - Paris 1862) later a teacher of Louis Pasteur, discovers optical activity. Biot was a voluntary during the 1792 war against the monarchists Allies against France. He recognized the celestial origin of meteorites in 1803 and completed the measurement of the earth meridian started by Jean-Baptiste Delambre (1749-1822) and Pierre Mechain (1744-1804). He nade the first precise measurements of the density of gases with François Arago (1756-1853) and evaluated the value of the magnetic field created by a linear current with Félix Savart (1791-1841) (Biot-Savart law). His most important contribution for biology is the definition of the laws governing polarisation of light, which he taught to Louis Pasteur.

1816 René Théophile Hyacinthe Laënnec (1781-1826) replaces direct auscultation by the use of the stethoscope, and introduces terms such as pectoriloque, ronchi, crépitations (Traité de l'Auscultation médiate, 1818). The instrument's daily use by an increasing number of clinicians was to yield a crop of murmers and other signs of cardiac and pulmonary origin.

1816 Mary Wollstonecraft Shelley (Somers Town 1797 - Bournemouth 1851) writes Frankenstein, a romantic prefiguration of biological engineering. The hero monster is usually taken for Dr Victor Frankenstein. The book is published two years later.

1817 James Parkinson (London 1755 - 1828) publishes An Essay on the Shaking Palsy, where he describes the neurological disorder we now know to be due to a lack of dopamine, later known as Parkinson's disease.

1817 Christian Heinrich Pander (Riga 1794 - Saint-Petersburg 1865) known as the founder of conodont paleontology, first describes the existence of three germ layers in chick embryos (later named Blätter by Wolff). The concept was later extended by Karl Ernst von Baer to include all vertebrates.

1817 William Smith (Churchill 1769 - Northampton 1839)'s Stratigraphical System of Organized Fossils shows that certain geological strata have characteristic series of fossils.

1817 In Cuvier's Le Règne animal, distribué d'après son organisation, the animal kingdom is divided into four groups Vertebrata, Mollusca, Articulata and Radiata, having each a special ground-plan. This is probably at the root of most of today's metaphors using the concept of "blueprint" (rather than the more appropriate concept of program, or of book of recipe).

1817 Joseph Bienaimé Caventou (1795 – 1877) and Pierre Joseph Pelletier (Paris, 1788 – Paris, 1842) isolate chlorophyll from plant leaves: published in Sur la matière verte des feuilles.

1817 Georg Wilhelm Friedrich Hegel (Stuttgart 1770 - Berlin 1831) publishes his Encyclopedia, where he describes the nature of Logic and of Organic Matter.

1817 Georg August Goldfuss (1782-1848) coins the name "protozoa" to describe animalcules present in water. The term was only formally accepted in 1920. He subsequently includes the Cnidaria into Protozoa.

1817 Louis Jacques Thénard (Louptière 1777 - Paris 1857) publishes his Traité de Chimie Elémentaire Théorique et Pratique, where he tries to understand the role of iron in hématosine (hemogloblin). This treaty was republishes and amended many times later on.

1818 Thénard discovers hydrogen peroxide.

1818 Louis Jacques Thénard (Louptière 1777 - Paris 1857) discovers hydrogen peroxide.

1818 The Library of the Surgeon General's Office is established in the USA (later to become the Army Medical Library and then the National Library of Medicine).

1819 Arthur Jacob (1790 - 1874) describes the layer of the retina containing the rods and cones (in the Philosophical Transactions).

1819 Proust identifies a molecule he names acide caséeux, and that we know today as the amino acid leucine.

1819 Louis Charles Adélaïde (Adelbert von) Chamisso de Boncourt (Château de Boncourt 1781 - Berlin 1838), known as a romantic poet and writer, and as a botanist and philologist, introduces the concept of alternation of generations (corresponding to meiosis and fertilisation).

1820 Christian Friedrich Nasse (Bielefeld 1778 - Marburg 1851), a figure of romantic anthropology, formulates the law which brings now his name: hemophilia occurs only in males and is passed on by unaffected females.

1820 Braconnot obtains from rotten cheese aposépédine which is none other than acide caséeux identified the previous year (leucine). He also creates a gelatin derivative he names glycocolle, and we know today as the amino acid glycine.

1820 The galvanometer, named after Galvani, is invented by Johann Salomo Christoph Schweigger (1779 - 1857). It is the first sensitive instrument for measuring and detecting small amounts of electricity.

1820 Caventou and Pelletier isolate quinine from the bark of Cinchona trees. They later isolate strychnine and brucine.

1821 Charles Bell describes facial paralysis. Although he reported several cases of facial paralysis, the condition now named as Bell’s palsy was not part of these early descriptions. In contrast, Nicolaus Anton Friedreich (1761–1836) of Würzburg (Germany) wrote an extensive thesis in 1797 about a condition, which he called Rheumatic Facial Paralysis and which is clearly what is named today Bell's palsy.

1821 Karl Asmund Rudolphi (Stockholm 1771 - Berlin 1832) founder of Berlin's zoological museum, publishes his Grundriss der Physiologie, where he states that the human genus should be divided into species, not into races. In this connexion, he declares that human beings cannot have derived from a single pair. His work is therefore at the root of "scientific" racism in German and Scandinavian countries, well before the Nazi period.

1821 Magendie discusses functional differences between dorsal and ventral roots of the spinal cord.

1821-1823 Jean-Louis Prévost (?1790 – 1850) and Jean-Baptiste André Dumas (Alès 1800 - Cannes 1884) report that the coloured matter in blood is made of an animal substance combined with iron peroxide.

1822 Karl Friedrich Burdach (Leipzig 1776 - Königsberg 1847) names the cingulate gyrus and distinguishes lateral and medial geniculate bodies.

1822 At the time of his death, René Just Haüy, elder brother of Valentin, publishes his Traité de cristallographie, where he establishes the rule for the cleavage planes in crystals.

1822 Henri Marie Ducrotay de Blainville (Arques 1777 - Paris 1850) pupil of Cuvier and Bichat publishes his Traité des animaux. He states that the two principal characteristics of life are "composition" and "décomposition", thereby starting to emphasize the role of metabolism in life. He is also one of the promoters of embryological research.

1822-1826 Geoffroy Saint-Hilaire experimentally produces abnormal development in chicks, providing an argument against preformation.

1822-1831 Jean-Baptiste Bory de Saint-Vincent (Agen, 1778 - 1846) publishes the major Dictionnaire classique d'histoire naturelle in 17 volumes (Rey et Gravier, Baudouin frères, Paris), presenting natural history with a materialistic and lamarckian point of view.

1822-1831 André Etienne Juste Pascal Joseph François d'Audebard, baron de Férussac (Le Chartron, 1786 - Paris, 1836) creates the Bulletin général et universel des annonces et des nouvelles scientifiques, a non academic precursor of the Comptes-Rendus de l'Académie des Sciences where he develops a visionary panorama of human knowledge with prominent thinkers (up to 300 authors collaborated to this endeavour). Interestingly the Bulletin is split into sections that have a very modern flavour (for example sciences naturelles et géologie (section 2) go together as well as sciences agricoles et économiques (section 4)). Statistics, with the influence of Augustin Cournot plays a central role in the Bulletin. 170 volumes were published during the short history of the Bulletin, that had a considerable influence, but has not yet been analysed in-depth. The lack of support of this extraordinary entreprise both by the French government and by the co-opted French academic world marked the onset of the decline of the influence of France in science.

1823 Prévost and Dumas show that urea is transported by the blood.

1823 Augustin Louis Cauchy (1789 - 1857) publishes his Résumé des leçons données à l'Ecole royale polytechnique sur le calcul infinitésimal, which triggers investigation in the nature of real numbers.

1823 Thomas Andrew Knight (Wormsley Grange 1759 - Downton 1838) a most distinguished horticulturist and fruit tree breeder, confirms reports of dominance, recessivity, and segregation in peas, but does not detect regularities. However all his papers mysteriously disappeared, which precludes further investigation.

1824 Marie Jean Pierre Flourens (Maureilhan 1774 - Montgeron 1867) opponent of Gall, states in his Recherches expérimentales sur les propriétés et les fonctions du système nerveux dans les animaux vertébrés that cerebellum regulates motor activity, divinding action into "action propre" and "action commune". In this work, Flourens details ablation of nerve centers to study behavior.

1824 John Charles Caldwell (1773 – 1853) publishes his Elements of Phrenology developing Gall's ideas (which remained fashionable for some time, in particular with positivist philosophers).

1824 Nicolas Léonard Sadi Carnot (Paris 1796 - 1832), though still labouring within the phlogiston (caloric) theory, advances the question of the nature of heat and energy substantially in his remarkable paper, Réflexions sur la puissance motrice du feu et sur les Machines propres a développer cette Puissance, by considering the question of the relation of quantity of heat to amount of work done, and by introducing the conception of a machine with a reversible cycle of operations.

1824 Henry Hill Hickman (1800 - 1830), a general practitioner, writes to Knight to describe his experiments showing that carbon dioxide can be used to anesthetize animals prior to surgery.

1824 Dutrochet further advances the cell principle, already described by Robert Hooke, and developed by Mirbel. He states that all organic tissues are actually globular cells of exceedingly small size, 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 composed. Dutrochet also discovers and names the phenomenon of "osmose".

1824 Magendie provides a first evidence for the role of the cerebellum in equilibration.

1824-1825 Prévost and Dumas repeat Spallanzani's filtration experiments, thus confirming the necessity of spermatozoa for fertilization, and describe cleavage in a frog egg.

1825 Jean-Baptiste Bouillaud (Garat, 1796 - Paris 1881) presents cases of loss of speech after frontal lesions and argues that speech is localized in the frontal lobes as Gall had suggested.

1825 Rolando describes the sulcus that separates the precentral and postcentral gyri in the brain.

1825 Pierre Fidèle Bretonneau (1771- Tours 1862) an epidemiologist, performs the first successful tracheotomy.

1826 Antoine Becquerel (1788-1878) invents the battery with two liquids.

1826 Adolphe-Théodore Brongniart (1801 - 1876) (son of Alexandre) first describes erratic movement of pollen grains under the microscope in a paper presented at the Académie des Sciences.

1826 Johannes Peter Müller (Koblenz 1801 - Berlin 1858) publishes his theory of "specific nerve energies", showing that sensory nerves could interpret an impulse in but one way.

1827 Richard Bright (Bristol 1789 - 1858) in his Reports of Medical Cases differentiates various causes of dropsy.

1827 Michel Eugène Chevreul (Angers, 1786 - Paris, 1889) names hématosine the red pigment found in blood.

1827 Magendie discovers the structure now known as the foramen of Magendie, an opening from the fourth ventricle, which is one in a system of four communicating cavities (ventricles) within the brain.

1827 Horace Bénédict Alfred Moquin-Tandon (Montpellier, 1804 - Paris, 1863) publishes a description of several leech species in his Monographie de la famille des Hirudinées. He later mistakenly changes his mind and group them all under the common name Hirudo medicinalis.

1827 Fourier publishes his Remarques générales sur les températures du globe terrestre et des espaces planétaires, where he provides the first account of the greenhouse effect that allows the Earth to have a mild temperature. He is thus the precursor of the account of global warming.

1827 Giovanni-Battista Amici (Modena 1786 - Firenze 1868) demonstrates his first achromatic microscope lens system.

1827 Karl Ernst von Baer (Piep estate 1792 - Dorpat 1876) discovers the egg of mammals in the ovary, which he describes in De ovi mammalium et hominis genesis. He regards the sperm cells as "Entozoa," i.e., parasites, and names them spermatozoa.

1827 Robert Brown (Montrose 1773 - London 1858), while looking for the molécules organiques postulated by Buffon, describes the erratic movement of pollen particles under the microscope. This process, since then known as the Brownian motion had been observed by Ingenhousz fourty years earlier. He also finds that Brongniart had made the same discovery earlier, but does not name Ingenhousz, and has his own paper published immediately in French and German.

1828 Publication of von Baer's Uber Entwicklungsgeschichte der Tiere (On the Development of Animals) which strongly opposes preformationism. Through this book von Baer created modern embryology. He rejects the Bonnet-Lamarckian theory of a uniform chain of development in the animal kingdom and adopts Cuvier's fixist ideas. However, he maintains that one must compare organs at different stages of development in different animals. He enunciates the law that the more dissimilar two animal forms are, the further we have to go back in evolutionary history to find an agreement, the common primitive form being the cell, followed by the egg and the first embryonic stages (biogenetic law).

1828 Friedrich Wöhler (Eschersheim 1800 - Göttingen 1882) synthesizes the first organic compound from inorganic components, preparing urea by reacting lead cyanate with ammonia.

1828 John Vaughan Thompson (Brooklyne 1779 - Sydney 1847) first collects and describes plankton. He also correctly describes barnacles as crustaceans.

1829 Barthélemy Charles Joseph Dumortier (1797-1878) publishes his Analyse des Plantes which is still at the root of many plant classifications.

1829 Louis-René Lecanu (1800–1871) shows the presence of cholesterol in an extract of hen egg yolk.

1829 Pierre Jean François Turpin (1775-1840), hailed as possibly the finest French natural botanical artist of his period, reports and illustrates his observations of cell division in algae.

1830 Dispute over construction of new microscopes. Following Charles Chevalier (1771-1841) and his son Vincent Chevalier (1804-1859) and Amici, Joseph Jackson Lister (London 1786 - 1869) (father of Lord Joseph Lister who discovered antiseptic techniques) makes lenses which corrected for chromatic and spherical aberration.

1830 Clash between Cuvier and Geoffroy Saint-Hilaire about the existence of a universal map of organisms. At the time, the quarrel settles at the advantage of Cuvier, but Geoffroy Saint-Hilaire, who recognized segmentation in insects and vertebrates, as well as inverted dorso-ventral segmentation at the junction between thorax and abdomen of Crustacea was right. One of his more infamous theories was that the segmented external skeleton and jointed legs of arthropods such as insects were equivalent to the internal vertebrae and ribs of vertebrates; insects literally live inside their own vertebrae and walk on their ribs. This prefigures the identification of homeogenes, much later on. While some of Geoffroy Saint-Hilaire comparisons seemed for a long time somewhat far-fetched, his idea of an "unité de plan" (amended into "théorie des analogues") was insightful: "Pour ces sortes de considérations il n'est plus d'animaux divers. Un seul fait les domine, c'est comme un seul être qui apparaît. Il est, il réside dans l'Animalité; être abstrait, qui est tangible par nos sens sous des figures diverses." Here we have clearly what would become the concept of development program. And quite remarkably, Cuvier stated that the features of the ink-fish, for example, have not resulted from the development of other animals, nor have in their own development produced any animal higher than themselves. This was against Lamarck's transformist view and demonstrated the limitations of the thought of Cuvier.

1830 Franz Julius Ferdinand Meyen (Tilsit 1804 - Berlin 1840) reports in Phytotomie his observations on algae, fungi and higher plants and concludes that each cell forms an independent, isolated whole; the cell nourishes itself, builds itself up, and elaborates raw nutrient materials, which it takes up, into substances and structures of very different types.

1830 Robiquet and Antoine Boutron-Chalard (?-?) isolate amygdalin discovered its hydrolytic splitting of by an extract of defatted bitter almonds. The agent was named "emulsin" by Liebig and Wöhler in 1837.

1830 With his microscope, Amici investigates the process of fertilization in plants and was able to trace the growth of the pollen tube through the style to the micropyle of the ovary.

1830 The German agronomist Karl Sprengel (1787-1859) conduces pioneering research that could be considered the start of agricultural chemistry, including disproving the humus theory and formulating the Law of the Minimum (stating that the limiting factor is that which controls growth, also known as Liebig's law).

1830 Berzelius coins the term "isomer" to express the existence of chemicals with the same atomic composition but different chemical properties.

1830 Robert Remak (Posen 1815 - Berlin 1865) makes his first discovery, the "fibers of Remak", unmyelinated nerve cell fibers. He later discovered and named the three layers of early embryos. Working with animal cells, he also showed that cells arise from preexisting cells by a process of binary fission.

1830-1833 Charles Lyell (Kinnordy House 1797 - London 1875)'s Principles of Geology creates stratigraphy, by advancing the theory of uniformitarianism, i.e., the view that geological formations are explainable in terms of forces and conditions observable at present. They were influential on Darwin's thoughts when he was aboard the HMS Beagle.

1830-1840 The use of leeches for bloodletting peaks. The rationale for bloodletting had changed with the evolution of new theories on the causes of diseases. Most physicians felt that the depleting effect of bloodletting was "cooling" and that it could relieve the congestion of inflamed capillaries without diminishing resistance to disease.

1830-1840 Justus Liebig (Darmstadt 1803 - München 1873) develops techniques of quantitative analysis and applies them to biological systems. His Law of the Minimum states that growth yield is proportional to the amount of the most limiting nutrient, whichever nutrient it may be. The idea that vital activity could be explained in physicochemical terms was an important one for investigators interested in the nature of life.

1830-1842 Isidore Auguste Marie François Xavier Comte (Montpellier 1798 - Paris 1857) writes the six large volumes of his Cours de Philosophie positive. Trying to imitate Aristotle he states that "positive" means "la même chose que réel et utile", substituting for the theological and metaphysical, which dominated during the previous times. Three stages in human thoughts explain for him the situation we witness today: the theological stage, in which personal divine powers are thought to dominate and explain all what happens in the Universe, the metaphysical, when impersonal forces substituted to the personal divine forces, and finally the positive stage, when the relevant question is no longer "why?" but sometimes "how?", and usually "what?". He is most remembered for his classification of sciences into six branches mathematics, astronomy, physics, chemistry, biology and sociology (a word coined by Comte). Each of these sciences is dependent on the preceding one, but has characteristics of its own. Comte biological speculation owe much to Blainville, rejecting both vitalism and mechanism. Life is defined as the relation between organism and environment, to be studied in its static (potentially active) and dynamic (actually active) states. See also What Makes Auguste Comte so Strange and so "Chinese"?

1831 Robert Brown publishes his observations reporting the discovery and widespread occurrence of "areola" (which he also names "nuclei") in cells. Brown distinguishes angiosperms from gymnosperms in his classification of the higher plants.

1831 Marshall Hall (Basford 1790 - Brighton 1857) publishes A Critical and Experimental Essay on the Circulation of the Blood, where he distinguishes capillaries from arterioles and venules on anatomical grounds. Using a Dollond achromatic microscope, Hall describes for the first time the minute arteriolo-venular communications that came to be known as"direct channels or thoroughfare channels."

1831 Erhard Friedrich Leuchs (1800-1837) describes the diastatic action of salivary ptyalin (amylase) on starch.

1831 Berzelius publishes his Traité de Chimie. Several reprinting were later published, where he quantifies the amount of iron peroxide found in hématosine (hemoglobin), as half of a percent. Many various names for hemoglobin begin to be used at the time: "zoohématine", "hématochroïne", "cruorine", among others. Cruorin was to dominate for several decades, with scarlet cruorin for "oxidised blood", and purple cruorin for "deoxidised blood".

1831-1836 The voyage of the Beagle, with Charles Robert Darwin (Shrewsbury 1809 - Downe 1882) aboard as naturalist.

1832 The sedative chloral hydrate is discovered.

1832 Robiquet isolates codeine from opium.

1832 Martin Heinrich Rathke (Danzig 1793 - Königsberg 1860) discovers the gill-slits in the embryo of birds and mammals. His work in comparative embryology is developed in Ûber die rückschreitende Metamorphose der Tiere where he describes the disappearance of organs (which remain present in lower species) during embryogenesis of higher species.

1832 Although Schleiden and Schwann later correctly articulated the cell theory, they were confused about the formation of cells, thinking that they arose by processes akin to precipitation or crystallization. The botanist Dumortier observing the process of cell division in algae and in plant cells recognizes that cells arose from preexisting cells by a process of binary fission.

1832 Candolle publishes his Physiologie végétale.

1832 Dutrochet shows that gas exchange in plants occurs via minute openings (stomata) on the surface of leaves and the deep cavities with which they communicate. He further demonstrates that only cells containing chlorophyll can fix carbon and thus transform light energy into chemical energy. In parallel, Dutrochet studies osmosis and suggests it may be the cause of ascent and descent of sap in plants. Throughout his work he endeavors to demonstrate that the vital phenomena of life can be explained on the basis of physics and chemistry.

1833 Marshall Hall describes a function which exists in the medulla independently of the brain: in this function a stimulus produces a response independently of sensation or volition. He names it "reflex."

1833 Jean Louis Rodolphe Agassiz (1807-1873) with his Recherches sur les poissons fossiles, founds paleoichthyology.

1833 Geoffroy Saint-Hilaire publishes his views that predate Darwin's vision: Influence du monde ambiant pour modifier les formes animales. "The external world is all-powerful in alteration of the form of organized bodies.. . these [modifications] are inherited, and they influence all the rest of the organization of the animal, because if these modifications lead to injurious effects, the animals which exhibit them perish and are replaced by others of a somewhat different form, a form changed so as to be adapted to the new environment." Darwin himself cited both the elder Geoffroy Saint-Hilaire and his son Isidore (who had continued to develop some of his father's ideas) as persons who had anticipated his theory to a certain degree.

1833 Jan Evangelista Purkinje (Purkyne) (Libochovice 1787 - Prague 1869) discovers 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 studies visual perception and devises the first system for classifying fingerprints. Purkinje later invented the word protoplasm to describe the embryonic material found in eggs.

1833 Johann Friedrich Meckel (Halle, 1781 - 1833), son and grandson of known anatomists, develops descriptive and comparative anatomy in the journal Archiv, and endeavours to write a thorough treaty System der vergleichenden Anatomie, which he could not complete before his death. This work is strongly influenced by Lamarck's transformism. Interestingly he is at the root of the "recapitulationist" school later developped in Germany (and still often used today), that ontogeny recapitulates phylogeny.

1833 Jean-Baptiste Joseph Dieudonné Boussingault, professor of analytical chemistry, recommends the use of iodized salt to cure goiter.

1833-1834 Anselme Payen (Paris 1795-1871) and Jean-François Persoz (Cortaillod 1805 - Paris 1868) further describe and isolate diastase (amylase) in powder form from barley malt, showing it to be heat labile. They postulate the central importance of what would later be named "enzymes" in biology.

1834 Michael Faraday (Newington 1791 - London 1867) enounces his laws of electrolysis.

1834 Félix Dujardin (1801-1860) proposes that single-cell animals should be classified in a group by themselves that he called Rhizopoda (now named protozoans).

1834-1840 Johannes Müller in his Handbuch der Physiologie des Menschen establishes a theory of specific nerve energies, outlining a mechanistic theory of thinking.

1835 Berzelius demonstrates that the hydrolysis of starch is catalyzed more efficiently by malt diastase than by sulfuric acid and publishes the first general theory of chemical catalysis.

1835 L. G. De Koninck and Jean-Servais Stas (Louvain, Belgium, 1813 – Bruxelles, Belgium, 1891) isolate the bitter glycoside phlorizin, a phenylproponoid derivative, from the bark of common apple trees (Pyrus malus). This molecule is the subject of intense research as an inhibitor of glucose recapture by the kidney (anti-diabetic effect).

1835 Robert Graves (1796-1853) describes exophthalmic goitre ('Graves' disease'). On the European continent, however, it is called 'Basedow's disease.'

1835 Rudolph Wagner (Bayreuth, 1805 - Göttingen, 1864) discovers a structure in oocyte germinal vesicles which he names keimfleck or macula germinativa. We now name it the nucleolus.

1835 Agostino Bassi (Lodi 1773 - 1856) demonstrates in Del mal del segno, calcinaccio o moscardino that a disease of silkworms is caused by a fungus and shows that the disease is contagious and can be transmitted naturally. This discovery gave impetus to the germ theory of disease.

1835 Dujardin associates the "sarcode" (later named protoplasm by von Mohl) of protozoa with life processes.

1835 Charles Cagniard-Latour (Cagniard de Latour) (1777-1859) finds that fermentation is always accompanied by the rapid growth and multiplication of plant-like organisms. Checking out his fermentations with a good microscope, he asserts that these Torulæ are minute organisms and that it is their activity that drives fermentation.

1835 Richard Owen (Lancaster 1804 - 1892), later known for his virulent campaign against Darwin, discovers Trichinella.

1835-1839 Hugo von Mohl (Stuttgart 1805 - Tübingen 1872) carefully describes some details of mitosis in plants. He recorded the appearance of the cell plate between daughter cells. He remarks that cell division is everywhere easily and plainly seen in terminal buds and root tips.

1836 Marc Dax (1770 - Montpellier 1837) describes a group of patients who could not speak properly and, according to his son Gustave, writes a memoir on the left hemisphere damage effects on speech.

1836 The famed bloodletter François Joseph Victor Broussais (Saint-Malo 1772 - Paris 1839) presents a series of twenty lectures on phrenology at the University of Paris. Broussais promoted the theory that all diseases result from inflammation caused by an excessive build-up of blood, and that the body must be weakened to be cured. He based his beliefs on his findings of blood in the mucous membranes of the gastrointestinal tract during postmortem examinations.

1836 Charles Giles Bridle Daubeny (1795- Oxford 1867), who would later strongly support Darwin, investigates the efficiency of different parts of the visible spectrum in photosynthesis.

1836 Gabriel Gustav Valentin (1810 - 1883), pupil of Purkinje, identifies the nucleus and the nucleolus in nerve cells. The nucleolus is the same structure as that discovered by Wagner the year before and later names it the nucleolus or kernkörperchen.

1836 Magendie demonstrates the need for dietetic nitrogen in his Leçons sur les phénomènes physiques de la vie.

1836 Robert Remak describes myelinated and unmyelinated axons.

1836 Theodor Schwann (Neuss 1810 - Köln 1882) reports the action of pepsin and describes its properties. Putrefaction and fermentation were then attributed to the action of micro-organisms.

1836 Charles Dickens (Landport 1812 - Gadshill 1870), famous for his novels, describes obstructive sleep apnea.

1836 Christian Gottfried Ehrenberg (Delitzch 1795 - Berlin 1876) discovers the giant axons in the Crustacea.

1836 Purkinje and Samuel Moritz Pappenheim (Breslau 1811 - 1882) discover that another organ than the stomach--namely, the pancreas--has a share in digestion,

1836 Stephan Ladislaus Endlicher (Pressburg 1805 - Wien 1849) expert in the Chinese language, publishes his Genera plantarum, which is the basis of all later plant classification.

1836 Gerhardus Johannes Mulder (1802-1880) carries out the first systematic studies of proteins. Mulder coins the word "protéine" (in French) from πρωτειος, primarius, as the main principle of all organic matter, in a Dutch journal published in French, although most people credit Berzelius for this invention.

1837 Purkinje describes cerebellar cells (one now bear his name); he identifies the neuron nucleus and dendritic processes.

1837 Berzelius classifies fermentation as a catalyzed reaction. He later identifies lactic acid as a product of muscle activity.

1837 Stas moved to Paris, to profit from the scientific milieu. As a collaborator of Dumas he performed a complete study of phlorizin, splitting it into phloretin and glucose.

1837 Johannes Dzierzon (1811 - 1906) is supported by Siebold who had studied the bee's sexual apparatus. In his work he demonstrates that the female bee is fertilized in the air. Dzierzon is the father of modern rational bee-keeping.

1837 Henri Milne-Edwards (1800 - Paris 1885) publishes his master piece: Histoire naturelle des crustacés.

1837 Heinrich Gustav Magnus (1802 - 1870) establishes experimentally again, after Lavoisier, that the change of blood colour during respiration is due to chemical changes occurring in the lungs.

1837 Dutrochet recognizes that chlorophyll is necessary for photosynthesis.

1837 Dujardin demonstrates that the spermatozoa are produced in the seminiferous tubules of the testis.

1837-1838 Theodor Schwann and Friedrich Traugott Kützing (1807-1893) in their turn, independently announce that yeast is a living organism which is responsible for fermentation. This starts the lengthy debate over whether fermentation is a chemical or a vital process, which later on will culminate in the debate between Louis Pasteur and Claude Bernard.

1837-1840 Johannes Peter Müller (Coblenz 1801 - Bonn 1858) publishes his Handbuch der Physiologie des Menschen für Vorlesungen, which was the authority on the subject in Germany for several decades. Starting with a semi-mystical view inspired by Goethe and Oken he investigates in particular sense perception. His description is very similar to that of Aristotle, placing emphasis on finality. He believes in spontaneous generation and maintains the immutability of both species and genera.

1837-1841 Avogadro publishes his treatise Fisica dei corpi ponderabili, where he establishes, contrary to the "indivisible" theory of Dalton, that oxygen and nitrogen in air are probably made of two atoms.

1838 Lignin is the second most abundant natural polymer on earth first observed by Anselme Payen.

1838 Matthias Jakob Schleiden (Hamburg 1804 - Frankfurt-am-Main 1881) publishes his "Beiträge zur Phytogenesis" in Müller's archives, an important contribution to understanding the genesis of plant tissues. He observes nucleoli but misinterprets their significance in considering them as nuclei forming within nuclei (which he named "cytoblasts"). Theodor Schwann applies the same erroneous theory of cell formation to animal tissues but correctly emphasizes that "cells are organisms and entire animals and plants aggregates of these organisms arranged according to definite laws."

1838 Ehrenberg's Die Infusionstierchen als vollkommene Organismen separates what he later named bacteria from other micro-organisms, seeing them as "complete organisms", with all organs found in higher organisms.

1838 Robert Remak suggests that nerve fiber and nerve cell are joined.

1838 Lecanu suggests that "hématosine" (hemoglobin) combines albumin and an iron oxide as separate substances.

1838 Theodor Schwann describes the myelin-forming cell in the peripheral nervous system ("Schwann Cell").

1839 Schwann proposes the cell theory in his work entitled Mikroskopische Untersuchungen über die Ubereinstimmung in der Struktur und dem Wachstum der Tiere und Pflanzen. Here he takes as his starting point Schleiden's cell-formation theory, and points out main differences between animal and plant cells. He states that the common principle of evolution is laid down for the most highly differentiated elementary parts of the organisms, and this principle of evolution is the cell-formation. This principle of the cell as the general unit of life is immediately universally accepted.

1839 Boussingault quantitatively studies the balance between the elementary constitution of the maintenance ration of a cow and that of its excretions and milk production.

1839 Magendie discovers the anaphylactic shock.

1839 Chevreul publishes his treaty De la Loi du contraste simuiltané des couleurs, where he describes the perception of colours by the human eye. He divides colors into two groups, primary colors (blue, yellow and red) and secondary colors obtained by mixing primary colors together. His theory was later summarized as "... je crois pouvoir affirmer qu'il est possible d'assujettir les couleurs à une nomenclature raisonnée en les rapportant à des types classés d'après une méthode simple.... Une matière colorée en rouge, en jaune, en bleu, en orangé, en vert et en violet ne peut être modifiée que de quatre manières dans l'emploi qu'on en fait en peinture ou en teinture...", thus defining "chromatic circles". This had a considerable impact on the evolution of painting and on the understanding of vision.

1839 Pierre François Verhulst (Bruxelles 1804 - 1849) develops the logistic model of population growth.

1839 Charles Chevalier (1804-1859) names "microtome" a slicing instrument meant for microscope preparations he had begun to construct in 1825.

1839 Francois Leuret (1797–1851) and Louis Pierre Gratiolet (1815-1865) map the folds and fissures of the cerebral cortex, and demarcate and name the frontal, temporal, parietal and occipital lobes, in particular the Rolandic sulcus for Luigi Rolando.

1839-1846 Purkinje proposes the term "protoplasm" for living matter and, together with von Mohl, establishes the protoplasm concept.

1840 Publication of Liebig's Tierchemie which united the fields of chemistry and physiology. Here Liebig points out that organic compounds in plants are synthesized from carbon dioxide of the atmosphere while nitrogenous compounds are derived from precursors in the soil. He proposes that fermentation is chemical and not dependent on living microbes. This begins a controversy over whether fermentation is a vital or a chemical process.

1840 Jules Sébastien César Dumont d'Urville (1790 - train accident near Versailles, 1842) on the Astrolabe reaches the Antarctic continent at Terre Adélie.

1840 Adolph Hannover (1814 -1894) uses chromic acid to harden nervous tissue for microscopic preparations.

1840 William Bowman (Nantwich 1816 - Dorking 1892) describes how the muscle is composed of fibrillae, surrounded by a substance that he calls sarcolemma.

1840 Michael Sars (Bergen 1805 - Christiania? 1869) publishes an account of the complete development of two species of jellyfish (published in French in the Annales des sciences naturelles in 1841). This makes him famous throughout Europe and is still of importance today.

1840 Jules Gabriel François Baillarger (1806-1890) discusses the connections between white and gray matter of cerebral cortex, revealing six layers. Remak will find the same four years later.

1840-1841 Owen coins the word "dinosaurus" (terrible reptile), which, becoming "dinosaure" was promised to an immense success in the public.

1841 Hugh Miller (1802-1856) investigates 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 publishes Footprints of the Creator in 1847, and opposes evolution to his death in 1856.

1841 Oken publishes his Allgemeine Naturgeschichte für alle Stände. Apart from his half-mystical beliefs, from quite another century, Oken tried to accept papers from different camps with great impartiality, he encouraged discussions and offered prizes for solutions, with the object of promoting research. Oken also to the initiative of another idea which has proved of immense value in the future: he organized meetings of scientists for the purpose of exchanging views and sharing ideas. In this way Oken extended the peer system which was only existing in Academia and in the Royal Societies of the time.

1841 Ehrenberg's opponent Félix Dujardin (1801-1862) demonstrates that infusoria do not have separate organs but consist of a membrane surrounding a mass full of vacuoles and granules he called "sarcode", term used in France, and later replaced by "protoplasm".

1841 Rudolf Albrecht von Kölliker (1817 - Würzburg 1905) traces the histogenesis of the spermatozoa and proves that they are differentiated tissue cells.

1841 Marshall Hall coins the term "spinal shock", Spinal shock refers to a transient loss of reflexes below the level of a spinal cord injury. Spinal Shock is an injury where the spinal column is subject to a forceful blow, but no lesion occurs. The reaction of the nervous system is such that it mimics a severed spine, and the signs and symptoms are identical.

1841 Following Bichat,Friedrich Gustav Jakob Henle (Fürth 1809 - Göttingen 1885) publishes his Allgemeine Anatomie where he makes the first description of many fine anatomic traits (in particular of the intestine).

1841-1845 Dujardin in his "Histoire Naturelle des Helminthes" describes the parasitic protozoa.

1842 Bowman describes the histological structure of the nephron.

1842 Publication of Schleiden's Grundzüge des wissenschaftlichen Botanik, which created extraordinary sensation, both favourable and unfavourable. Following Jacob Friedrich Fries (Barby 1773 - Jena 1843), professor of philosophy at Jena, Schleiden declares that the aim of natural science is to relate all physical theories to purely mathematical ground of explanation. He maintains, with Kant, the contrast between subject and object, and develops a dualistic approach which was, at the time in sharp opposition with that of theologians (who were monists, following Hegel).

1842 Benedikt Stilling (1810 - 1879) is the first to study the spinal cord in serial sections.

1842 Julius Robert von Mayer (Heilbronn 1814 - 1878) enunciates in the Annalen of Chemie the first law of thermodynamics and its applicability to living organisms.

1842 Herrmann Ludwig Ferdinand von Helmholtz (Postdam 1821 - Berlin 1894) develops an important research (Über die Erhaltung der Kraft published in 1847) in which the law of the indestructibility of energy is stated (the first law of thermodynamics). This is from this work that the theoretical formula of this law has been adopted ever since. Helmoltz was not aware of Mayer speculation, but the latter was bitterly affected that no reference had been made to his work. However, in contrast to Mayer, he had based his theory on experimental facts rather than on theoretical speculation, and history of natural sciences shows that theoretical conclusions are seldom given the same significance as those derived from experiments. The notion of proof remains central in science, especially in biology, and it will be interesting to see when the theoretical proof will reach the same level of confidence as that of the experimental evidence.

1842 Johann Japetus Steenstrup (1813 - 1897) describes the alternation of sexual and asexual generations in plants and animals.

1842 Liebig re-establishes in a convincing way that the blood corpuscle that change colour upon respiration are made of two separate components, one containing iron, that is itself a compound associated to oxygen, since it is decomposed by hydrogen sulfide in the same manner as iron oxides.

1842 Crawford Williamson Long (1815-1878) uses ether for anaesthesia on man.

1842 Karl Wilhelm von Nägeli (Kilchberg 1817 - München 1891), a pupil of Candolle, publishes his work Zur Entwicklungsgeschichte des Pollens bei den Phanerogamen where he describes accurately cell division.

1842-1850 Pierre Charles Alexandre Louis (1787-1872) founds medical statistics and clinical epidemiology. His work established that blood letting was not beneficial for the patients.

1843 Oliver Wendell Holmes (1809 - 1894) observes the contagiousness of puerperal fever:The Contagiousness of Puerperal Fever.

1843 Owen elaborates the concepts of homology and analogy as "the same organ in different animals under every variety of form and function." .

1843 James Braid (Earlsferry 1795 - Manchester 1860) coins the term "hypnosis".

1843 Antoine Becquerel, who discovered piezoelectricity summarizes the history of his invention of non polarisable battery with two liquids (Note sur l'historique des piles à courant constant). His battery, using copper sulfate or nitrate, a neutral saline solution, a membrane and a copper blade was invented in 1826, while Daniell invented a counterpart only in 1836.

1843 Liebig speculates that organic acids such as oxalic, tartaric, or malic are intermediates in the production of carbohydrates by plants.

1843 Helmholtz separates a putrefying or a fermenting liquid from one which was simply putrescible or fermentable by a filter which allows the fluids to pass through, but stops the passage of solids. The result is, that while the putrescible or the fermentable liquids become impregnated with the results of the putrescence or fermentation which is going on the other side of the membrane, they neither putrefy (in the ordinary way) nor ferment; nor were any of the organisms which abounded in the fermenting or putrefying liquid generated in them.

1844 Darwin makes his first sketch of the theory of natural selection.

1844 Remak provides an illustration of the 6-layer cortex.

1844 Karl Wilhelm Ludwig (1819-1884) shows that the Malpighian corpuscle of the kidney acts as a passive filter and that the waste products in the filtrate are concentrated as they passes through the tubules.

1844 Horace Wells (1815-1848) is the second American to "discover" inhalation anesthesia (with ether) for tooth extraction on his own person.

1844 John William Draper (Liverpool 1811 – New York 1882) shows that plants grown in solutions of sodium bicarbonate can liberate oxygen in the light.

1845 Adolf Wilhelm Hermann Kolbe (1818-1884), a pupil of Wöhler's, synthesizes acetic acid, previously obtainable only as the result of vital activity, from nonorganic materials. He later developed a method for the synthesis of salicylic acid.

1845 Alexander von Humboldt publishes Kosmos, a general view of known facts about the Universe. He places emphasis on the lifestyle of organisms (plants in particular) which sets the stage for ecology.

1845 Mayer prints out by himself Die organische Bewegung in ihrem Zusammenhange mit dem Stoffwechsel, where he further elaborates his theory of conservation of energy. This had been refused by the editors of scientific journals despite the fact that this pamphlet applied the laws of conservation of energy to relation between muscular energy and digestion as well as to the assimilation of energy by plants (a process that Mayer thought to be at the origin of life, and solar energy to be its ultimate source). In consequence this demonstrated that it was superfluous to hypothesize an extra energy source for the origin of energy in living bodies. This was not well accepted by the vitalist biologists of the time.

1845 Shortly after that James Prescott Joule (Salford (Sale) 1818 - 1889) publishes a theory based on years of experiments but giving a more correct number to represent the heat equivalent. It is however quite disputable that he could have really obtained accurately the corresponding values.

1845 Remak describes the nerve fibers in the sympathic system. He demonstrates also that nerve cell sprouting is responsible for growth of nerve fibers during development of the embryo.

1845 The Reverent Miles Joseph Berkeley (1803-1889) demonstrates that a mold is responsible for potato blight. He also made important contributions to the classification of fungi.

1845 Luigi Porta (Pavia, 1800- 1875) publishes an article on surgery of arteries and veins “Delle alterazioni patologiche delle arterie per la legatura e la torsione, that was to play an important role in cardio-vascular surgery.

1845 Kölliker extends his findings about spermatozoa to the ovum, from which the organism is derived by cell division.

1845 Karl Theodor Ernst von Siebold (Würzburg 1804 - München 1885) defines the protozoa as we know them today: "Die Tiere in welchen die verschiedenen Systeme der Organe nicht scharf ausgeschieden sind, und deren unregalmässige Forme und enifache Organization sich auf eine Zelle reduzieren lassen"(animals whose organization is reducible to one cell). Later, he discovers parthenogenesis in the honeybee.Siebold resolves the dispute between Ehrenberg and Dujardin, showing, in his Comparative Anatomy, that various forms previously supposed to be Infusoria or distinct groups should be either separated or grouped together into Protozoa, the Primary Animals, "Tiere, in welchen die verschiedenen Systeme der Organe nicht scharf ausgeshieden sind, und deren unregelmässige Form und einfache Organisation sich auf eine Zelle reduzieren lassen."

1846 Siebold and Friedrich Hermann Stannius (Hamburg 1808 - Rostock 1883) publish the Lehrbuch der vergleichenden Anatomie der Wirbellosen Thiere where Siebold takes the invertebrate section and Stannius that of the vertebrates. By many aspects this work is similar to Owen's, but much less known (and less speculative).

1846 Édouard Séguin (Clamecy, 1812 - New York, 1880) describes the characteristic features of the children affected by the congenital disease now known as Down's syndrome.

1846 Côme-Damien Degland (Armentières, 1787 - Lille, 1856) publishes his Ornithologie Européenne, ou Catalogue analytique et raisonné des oiseaux observés en Europe extensively describing European birds; he is at the origin of the establishment of the Museum of Natural History at Lille.

1846 Carlo Matteucci (Forli 1811 - Ardenza 1868) a former foreign student at the Ecole Polytechnique in Paris invents the kymograph, an instrument for recording variations in pressure, as of the blood, or in tension, as of a muscle, by means of a pen or stylus that marks a rotating drum. In 1842 he had discovered using a preparation known as the 'rheoscopic frog' that an electrical current accompanied the contraction of all muscles, including cardiac muscle.

1846 William Thomas Green Morton (1819-1895) and John Collins Warren (1778-1856) spread the practice of anesthesia by demonstrating the use of ether anesthesia at the Massachusetts General Hospital.

1846 Pierre Joseph van Beneden (1809 - Louvain, 1894) establishes that a cysticercus is an incomplete taenioid.

1847 George Boole (Lincoln 1815 - Cork 1864) in The Mathematical Analysis of Logic : being an essay towards a calculus of deductive reasoning establishes the formal laws of logics which are at the core of computer sciences and classification.

1847 Concurrently with the work carried out by Bilharz in Egypt, other Scientists and Physicians were also becoming aware of this disease, particularly in Japan. Yoshinao Fujii (1818 - 1895) a physician working in Numakuma County, reports a disease he had noted in the district of Kawanami and identifies the causative agent of this disease, Schistosoma japonicum, four years before Bilharz described his new trematode,

1847 The agriculture and horticulture society of Utrecht gives is gold medal in an exhibition to a flower from the Polygonaceae family, Fallopia japonica. One year later this flower is sold in its catalogue. This is the beginning of the invasion of Europe by this plant, and several of its cousins, a plague that is, despite its highly restricted initial genetic diversity, now out of control, occupying river banks in particular and killing indigenous plants. Since this time the plant underwent a doubling of its genome (it is now octoploid, with 88 chromosomes) and produced a large variety of mutants that adapt to a large set of biotopes.

1847 Rudolf Ludwig Karl Virchow (1821 - Berlin 1902) creates the Archiv für pathologische Anatomie und Physiologie.

1847 Wilhelm Friedrich Benedikt Hofmeister (Leipzig 1824 - Lindenau 1877) in Die Entstehung des Embryo der Phanerogamen makes sketches of microspore mother cells from Tradescantia which show chromosomes in various stages of meiosis, but he fails to grasp their significance.

1847 The same year Augustus DeMorgan (Madura 1806 - London 1871) publishes his Formal Logic in London.

1847 James Young Simpson (Bathgate 1811 - Edinburgh 1870) invents anesthesia with chloroform.

1847-1849 Arnold Adolphe Berthold (?-?) demonstrates that transplant of a rooster's testis prevents atrophy of the comb after castration. He then shows that the testis produces a blood-borne substance conditioning sexual characteristics.

1847-1849 Ignaz Philipp Semmelweis (1818-1865) investigates the cause of puerperal fever and introduces disinfection of hands in obstetrics; he shows that cleaning hands appropriately can cut the number of deaths from puerperal fever by a factor of one hundred. Unfortunately, he is opposed by high profile professors of medicine protecting their privileges, and his method is not implemented as it should have been, resulting in thousands of premature deaths of women.

1848 First memoir of Louis Pasteur (Dôle 1822 - Villeneuve l'Etang 1895) at the Académie des Sciences on sulfur crystallisation: Mémoire sur la relation qui peut exister entre la forme cristalline, la composition chimique et le sens de la polarisation rotatoire.

1848 H Emanuel Merck (1794 - 1855) discovers papaverine in opium.

1848 Emil Heinrich Du Bois-Reymond (Berlin 1818 - 1896) publishes his Untersuchungen über tierische Elektrizität on animal electricity (in particular that of electrical fish). This was the first part of a work which was never completed. One of his major contribution was the concept of "electrotonus" a term coined to refer to potential changes produced by externally applied current. He stated that von versciedenen Standpunkten aus aufgenommene Abstractionhen der Dinge wie sie sind. Sie ergänzen einander und sie setzen einander voraus which allows him to conclude that the difference between the organic and inorganic nature is of no importance whatsoever.

1848 Phineas Gage (1823-1860) has his brain pierced by an iron rod (the rod and his skull are preserved at Harvard Medical School). He does not die, but his behaviour is drastically altered. Alexander Luria, one century later in Soviet Union, described similar phenomena in patients wounded during the battle at Stalingrad.

1848 Siebold establishes Protozoa as the basic phylum of the animal kingdom.

1849 Helmholtz measures the speed of frog nerve impulses.

1849 Henri Victor Regnault (Aix la Chapelle 1810 - Paris 1878) and Jules Reiset (1818 - 1896) publish extensive comparative studies of respiration and calorimetry. Inspired by their work Jules Vernes in De la Terre à la Lune, proposes that an apparatus made by Reiset and Regnault produces oxygen in the projectile carrying the heros to our satellite.

1849 John Snow (1813-1858) discovers by epidemiological studies the mode of cholera transmission. This is published in On the Mode of Communication of Cholera.