translation: Thesis of Medicine 1874
First steps in immunology, symbiosis
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1890 Richard Altmann in Die Elementarorganismen und ihre Beziehungen zu den Zellen describes procedures for staining organelles (now known as mitochondria), studies their distribution, and postulates them to have metabolic and genetic autonomy. This triggers a long debate between scientists supporting his views and scientists seeing these granules (which he called bioblasts) as staining artefacts. His motto here is "omne granulum e granulo"...
1890 Pierre Mazé (1868 - 1947) at the Institut Pasteur isolates from root tubercles bacteria that Liebig had claimed were fixing nitrogen for some plants (Leguminosae), a clear case of symbiosis.
1890 The numerical equality of paternal and maternal chromosomes at fertilization is established by Boveri in Germany and Jean-Louis-Léon Guignard (1852-1928) in France.
1890 Theobald Smith (Albany 1859 - 1934) pioneer of american microbiology, demonstrates the transmission of a disease by an arthropod vector: the infection of cattle with the sporozoan Babesia by the tick Boophilus. This will trigger spreading of a new concept in the transmission of diseases.
1890 Wilhelm Ostwald, teacher of Arrhenius, van t'Hoff and Nernst, establishes the first bases of the membrane theory of nerve conduction.
1890 William James (New York City 1842 - Chocorua 1910), the brother of the novelist Henry, publishes The Principles of Psychology, where he discusses the problem of consciousness in terms similar to those of Thomas Huxley: we are conscious automata.
1890 Sergei Nikolaevitch Winogradsky (Kiev, Russia, 1856 - Brie Compte-Robert, France, 1953) isolates nitrifying bacteria from soil. He invents a device known after his name (the Winogradsky column) to explore microbial communities in soil layers.
1890 von Behring discovers antibodies.
1891 Eduard Buchner (1860-1917) professor of chemistry in Berlin demonstrates that alcoholic fermentation is not provoked by a vital action of yeast-fungi, but that a product they make are responsible of the process.
1891 Hans Buchner proposes the existence of antibacterial proteins in blood serum which he calls "alexines". This begins a protracted debate with Metchnikoff, who championed a cellular theory of immunity. Both were right...
1891 Quincke introduces the use of spinal lumbar puncture as a diagnostic and therapeutic aid.
1891 Luigi Luciani (1840 - 1919), who investigates localization in the brain, publishes a manuscript on the cerebellum Il cervelletto: nuovi studi di fisiologia normale e patologica.
1891 Waldeyer proposes the neuron theory of the nervous system (coining the term "neuron" for the nervous cells thought to be responsible for all nervous system activity).
1891 George Redmayne Murray (1865-1939) prepares emulsions of dried sheep thyroid in glycerine. He uses these with considerable success on patients suffering from myxoedema (hypothyroidism).
1891 Hans Dreisch (1867-1941) at the Stazione zoologica di Napoli discovers 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 contradicts Wilhelm Roux's mosaic theory.
1891 Dareste publishes his Recherches sur la production artificielle des monstruosités ou essais de tératogenie expérimentale.
1891 Alexandre Calmette (Nice 1863 - Paris 1933) creates the Institut de Bactériologie d'Indochine, to become the Institut Pasteur de Saïgon in 1904.
1891 Marie Eugène François Thomas Dubois (1858 - 1940) discovers the Java Man and names it Pithecanthropus erectus, now known as Homo erectus.
1892 Dimitri Iosifovich Ivanovski (1864-1920) staying in Crimea to study a disease infecting tobacco plants with unusual symptoms, discovers a disease-causing agent smaller than bacteria: virus. Taking leaves from tobacco plants which had a common disease called mosaic, he extracts their sap and rubs it onto healthy leaves. These leaves soon showed symptoms of the disease. He performs the experiment again, but this time he filters the sap through ceramic filters with pores so small that they retained all the bacteria known at that time. He rubs more tobacco leaves with the filtered sap, but once again they are infected. Ivanovsky, who was a prudent scientist (as all scientists should be), did not interpret his results as a discovery. He simply records in his laboratory notebook his opinion that this contamination was probably caused by a toxin secreted by the bacteria, and which was not retained by the filter.
1892 Albert Frank publishes his Lehrbuch der Botanik in which he describes many cases of symbiosis. Curiously, although this book is widely spread, the origin of the term "symbiosis" ("Symbiose" in German and in French) is often ascribed to Anton de Bary (see 1877-1879 above).
1892 The publication of August Weismann's book Das Keimplasma (The Germ Plasm) emphasizes meiosis as an exact mechanism of chromosome distribution.
1892 Theobald Adrian Palm (1848-1928) discovers a relationship between the geographic distribution of rickets and the amount of sunlight in the region.
1892 Salomon Eberhard Henschen (1848 - Uppsala 1930) locates the centre of vision in the brain to calcarine fissure.
1892-1902 Jacob Johann von Uexküll (Keblas 1864 - Capri 1944) is the head of the Physiology department at the Stazione zoologica in Napoli, and, for ten years, he carries out original and ingenious experiments on the nervous and muscular systems of marine animals. Uexküll is a pioneer of modern behavioral biology, investigating the environmental relations, the ‘sphere of function’ (Umwelt) as he calls it, which connect the individual to its environment.
1893 Paul Emil Flechsig (Zwickau 1847 - 1929) analyses where myelinization occurs, and shows that certain regions of the brain have a mature appearance at birth, whereas other cortical areas including continue to develop, as though their maturation depended on the acquisition of experience. This works announces the concept of brain plasticity.
1893 Roscoe Pound (1870 - 1964) publishes an article, Symbiosis and Mutualism, in which, reasoning in terms of costs and benefits, he tries to separate the two concepts. Mutualism requires that there is mutual benefit, with one partner always dominating, while the partners may have an independent life. In contrast symbiosis assumes that the partners are no longer autonomous entities in the absence of each other. In this work he wrongly argues that microbes are always parasites (acting as "thieves").
1893 Charles Scott Sherrington (London 1852 - Eastbourne 1952) working on spinal reflexes, coins the term "proprioceptive".
1893 Adrien Loir (Lyon 1862 - Le Havre 1941) creates the Service des vaccinations antirabiques et des fermentations, to become the Institut Pasteur de Tunis in 1900.
1893 Oscar Hertwig obtains twin embryos in the newt by constricting the egg.
1893 Eduard and Hans Buchner find a way to make a cell-free liquid extract of microorganisms. They were using a yeast extract for pharmaceutical studies and added a thick sugar syrup to stop any bacterial action. They fully expected the sugar to act as a preservative, but it had the opposite effect and carbon dioxide was produced. The sugar had fermented, producing carbon dioxide and alcohol, in the same way as if whole yeast cells had been present.
1893 Shosaburo Watase (1862-1929), a Japanese zoologist trained in America, suggests that the particles present in cells are symbionts.
1893 Thomas Henry Huxley publishes his simplistic but fashionable Evolution and Ethics, which states that human morality is not in line with natural selection processes. He argues that the struggle for existence (curiously only understood as a "fight", the strongest being the necessary winner) is at the basis of all evolution.
1893 Ferdinand Blum (1865 – 1959) uses formaldehyde as a brain fixative.
1893 Wilhelm Ostwald proves that enzymes are catalysts.
1893 Louis Antoine Marie Joseph Dollo (1857 - 1931) points out that in evolution it is harder to gain a complex feature than to lose it, hence the irreversibility of evolution ("Dollo's law").
1893 Bartolomeo Gosio (1863 - 1944) publishes his study on the toxic gases generated by microbial activity on arsenic compounds: Action de quelques moisissures sur les composés fixes d'arsenic. "Gosio gas" is the garlic scenting now known as trimethylarsine.
1893 Wilhelm His investigates the specialized conducting tissue of the atrio-ventricular node and bundle of the heart.
1894 Dreisch proposes a new version of epigenesis, that all nuclei of the cells of an organism are equipotential but varied in their activity in accordance with the differentiation of tissues. This is a first view of the concept of gene expression.
1894 William Bateson's (Whitby 1861 - 1926) Materials for the Study of Variation Treated with Especial Regards to Discontinuity in the Origin of Species emphasizes the importance of discontinuous variations, foreshadowing the rediscovery of Mendel's work.
1894 Karl Pearson (London 1857 - London 1936) publishes the first in a long series of contributions to the mathematical theory of evolution. Methods for analyzing statistical frequency distributions are developed in detail.
1894 Emil Fischer conduces an extensive series of investigations which still form the basis for our notions of enzyme specificity. He coins the lock and key (Schloss und Schlüssel) metaphor that is still in use today to explain enzyme catalysis.
1894 Conwy Lloyd Morgan (1852 - 1936) establishes the basic principles in the study of animal behavior including his famous canon which states that the actions of an animal should be interpreted in terms of the simplest mental processes.
1894 William Maddock Bayliss (1860 - 1924) and Ernest Henry Starling (1866 - 1927) study electric currents in the mammalian heart.
1894 Alexandre Yersin (Morges 1863 - Nha Trang 1943) isolates and identifies the bacillus responsible for plague in Hong Kong. This bacillus is now named Yersinia pestis, after his name.
1894 George Oliver (1841-1915) and Edward Albert Sharpey-Schäfer (1850 - 1935) first demonstrate the action of a specific molecule, later named 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 pressure.
1894 Franz Nissl (Frankenthal, Pfalz, 1860 - München, 1919) stains neurons with dahlia violet.
1894-1897 Gustav Born (1851 – 1900), the father of the physicist Max Born makes heteroplastic grafts of parts of frog and toad embryos.
1895 Wilhelm His uses the term hypothalamus for the first time.
1895 Philipp Stoehr (1849-1911) First publishing of Lehrbuch der Histologie und der mikroskopischen Anatomie des Menschen : mit Einschluss der mikroskopischen Technik. Stoehr will state that the hypochord plays no role in directing the formation of any other embryonic structure.
1895 The ophtalmologist Thomas D Dunn (?-?) finds a new proof of brain hemisphere dominance and specific memory of topographic places in Double hemiplegia with double hemianopsia and loss of geographical centre.
1895 Wilhelm Konrad Roentgen (1845-1923) discovers X-rays, which are soon to be applied in the visualization of bodily structures and in the induction of genetic mutations (both intentionally and accidentally).
1895 Arrhenius suggests that carbon dioxyde might be of importance in the increase of the Earth temperature, in his theory of the "warm greenhouse" now understood as the cause of present global warming.
1895 Quincke performs lumbar punctures to study the nature of the cerebrospinal fluid.
1895 Charles Ernest Overton (1865-1933) proposes that the cellular membranes consist of a peculiar category of molecules that he calls lipoids, and that element dissolved in these permeate the cell walls.
1895 The journal Wilhelm Roux's Archiv für Entwicklungsmechanik der Organismen is founded.
1895 Jules Henri Poincaré (Nancy 1854 - Paris 1912) probably the last "universal" mathematician poses the mathematical foundations of what would become Einstein's theory of relativity and publishes his Analysis situs, which creates the domain of Topology. He is recognized with Lorenz and Einstein as the father of the theory of special relativity. His importance in science is stressed by his many books on the nature of science and discovery. For biology, the sentence he states about mathematics "La mathématique est l’art de donner le même nom à des choses différentes" (Mathematics is the art of giving the same name to different things) justifies the present endeavour to create a chronology of biological discoveries! Contrary to a general feeling, biology is not about anecdotes but it displays laws carried over by different things.
1895 David Bruce (Melbourne 1855 - 1931) investigates the life cycle of the protist blood parasite now named after him Trypanosoma brucei and the role of the tse-tse fly in its transmission.
1895 Adolf Magnus-Levy (1865-1955) finds by means of direct calorimetric measurements that persons with myxoedema have a lowered heat production. He also finds that administration of thyroid preparations to normal or myxoedemic patients raises the metabolic level.
1895 Jules Bordet (Soignies, Belgique, 1870 - Bruxelles, 1961) discovers, in the laboratory of Metchnikoff at the Institut Pasteur the fixation of the complement. The complement fixation assay can be used to look for the presence of i) specific antibody or ii) specific antigen in a patient's serum.
1895 Theobald Smith produces a hemorrhagic deficiency disease (scurvy) in guinea pigs deprived of leafy foods, thus preparing the discovery of vitamin C.
1895 Back from Hong Kong, Yersin stops in Nha Trang, where he begins to study bovine plague and creates the Institut Pasteur de Nha Trang (Viêt-Nam).
1895 James Mark Baldwin (1861-1934) publishes Mental development in the child and the race : methods and processes. He is one of the first to understand the importance of alteration of individuals during ontogeny, with the resulting effect of production of a phenocopy. The "Baldwin effect" states that selection of genotypes by the environment will be channeled in the same direction as non-hereditary adaptive modifications, so that the modal behavior of all animals in a species is rather constant despite individual genetic variations.
28 december 1895 Antoine Lumière (1840 - 1911), the father of August and Louis organizes the first public presentation of cinematograph, with a small orchestra to fill the acoustic side.
1895-ca 1900 Yan Fu 嚴復 (1854-1921) translates into Chinese many famous Western works, introducing philosophy and science in a modern form in China. This is the first introduction of Science as we understand it in China. The major emphasis is however still on ethics and politics (translation of L'esprit des Lois from Montesquieu, Evolution and Ethics of Thomas Huxley, On Liberty, but also A System of Logic by John Stuart Mill...).
1896 Leçons sur la Cellule, Morphologie et Reproduction is published by Louis Félix Henneguy (1850–1928).
1896 John Scott Haldane (1860-1936) publishes in The Lancet an important article, The Causes of Death in Colliery Explosions showing that the miners did not die of the blasts but were succumbing to carbon monoxide poisoning.
1896 Conwy Lloyd Morgan (1852 - 1936) publishes his treaty Habit and Instinct summarizing his first behavioural experiments.
1896 The Russian Hydrographic Survey of the Biology of Lake Baikal , led by F. Drizhenko, is undertaken. This survey finds several unique endemic freshwater animals that have become extinct in the rest of the world.
1896 Alexandr Fyodorovitch Brandt (?-?) in Saint Petersburg writes an essay where he endeavours to establish that the "struggle for existence" is only one component of evolution, while "mutual aid" is always an important factor.
1896 Kölliker coins the term axon.
1896 Eugen Baumann (1868 - 1933) reports that the thyroid contains 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.
1896 Herbert Edward Durham (1866 - 1945) and Max von Gruber (Wien 1853 - Berchtesgaden 1927) discover specific agglutination by serum, and Fernand Isidore Widal (Dellys, Algérie, 1862 - Paris, 1929) finds that blood serum from a typhoid patient agglutinates typhoid bacilli, thus introducing the process of serologic diagnosis.
1896 Max von Frey (1852 - 1932) uses human hairs or other bristles mounted in a handle to map cutaneous sensitivity on a piece of skin to test the somatosensory system.
1896 Camillo Golgi discovers the intracellular structure now known as the Golgi apparatus.
1896 Joseph François Félix Babinski (1857 - 1932) describes what is now known as the "Babinski Reflex" or "Signe de Babinski", an inversion of the cutaneous foot sole reflex, which is a proof of a lesion in the pyramidal pathway.
1896 Another spectacular case of serendipity: Antoine Henri Becquerel (Paris 1852 - Le Croisic 1908) studies, at the suggestion of Poincaré, the "X"-rays just discovered by Röntgen, and, after having kept some uranium salts on a photograph plaque that he could not use because the day was cloudy, finds that the plaque looks as if it had been exposed to light. He then shows that all uranium salt emit rays which can react with photograph plaques in the dark. This was the discovery of radioactivity, that, during forty years was used to investigate the nature of atoms.
1896 Albrecht Kossel (1853 - 1927) discovers histidine.
1896 Emil Kraepelin describes cases of "dementia praecox", a condition that will later be labelled schizophrenia.
1897 Karl Ferdinand Braun (Fulda 1850 - Brooklyn 1918) invents the cathode-ray tube for use as the oscilloscope.
1897 Christiaan Eijkman (Nijkerk, 1858 - Utrecht, 1930) produces experimental polyneuritis in chickens by feeding them polished rice, and calls attention to rice hulls as containing the preventive agent of human beriberi.
1897 Wilhelm Ostwald demonstrates that the iodine of the thyroid is firmly bound to a globulin-like protein and introduces the term "thyroglobulin".
1897 In The Will to Believe and other Essays in Popular Philosophy William James remarks that "he who says 'Better go without belief forever than believe a lie!' merely shows his own preponderant private horror of becoming a dupe."
1897 Oscar Hertwig centrifuges frog eggs and analyzes the effect of yolk distribution on cleavage.
1897 Ivan Petrovich Pavlov (Ryazan 1849 - 1936) publishes his work on the physiology of digestion, but he is mainly known for his work on conditioned behavior.
1897 Albert Schneider (1863-1928) lichenologist at the University of Illinois elaborates on Frank, Boveri, Altmann and other's views about genetic continuity of the granules present in plant and animal cells, stating: "The plasmic bodies, such as chlorophyll granules, leucoplastids, chromoplastids, chromosomes, centrosomes, nucleoli, etc., are perhaps simply the symbionts comparable to those in the less highly specialized symbiosis." The Phenomena of Symbiosis
1897 Joseph John Thomson (1856-1940) discovers the electron.
1897 Sherrington coins the term "synapse" to describe contact between nerve cells. He deduces the existence of synapses by showing that individual nerve cells can exert integrative influences on other nerve cells by graded excitatory or inhibitory synaptic actions.
1897 Thomas Hunt Morgan (Lexington 1866 - 1945) publishes his first key work: The Development of the Frog's Egg; An Introduction to Experimental Embryology.
1897 Eduard Buchner (1860-1917) resolves the Liebig-Bernard-Pasteur controversy by producing fermentation in cell-free yeast extracts containing zymase. Although he demonstrates that living yeast cells are not necessary for fermentation, this in no way proved that Liebig's proposed mechanism was correct.
1897 Felix Hoffman (1868 - 1946), a chemist working in a laboratory owned by Friedrich Bayer, in Elberfeld, Germany, was stimulated by earlier work on acetylation and he formulated a pure and stable form of acetylsalicylic acid. Hoffman's work was motivated by the suffering of his father, who hadsevere arthritis, and could not tolerate salicylic acid. Hoffman and Bayer give the name A-spirin to the new preparation. This appears to come from acetylation (A-), together with Spirin, part of the name for Meadow-sweet (Spiraea ulmaria), a plant rich in salicylates.
1897 Gabriel Bertrand (1867-1962) coins the term "coenzyme" to designate inorganic substances which were necessary to activate certain enzymes.
1897 John Jacob Abel (Cleveland 1857 - 1938) and Albert Cornelius Crawford (?-?) isolate the first hormone, later named epinephrine by Jokichi Takamine (Takaoka 1854 - New York 1922).
1897 The Geological Survey of Canada finds rich fossil beds containing Upper Cretaceous dinosaur fauna along the Red Deer River in Alberta.
1897 André Huot (?-?) discovers that some fish have aglomerular kidneys, proving that renal tubules can secrete and resorb substances (Recherches sur les poissons lophobranches).
1897 Nicholas Kulchitsky (Kronstadt 1856 - London 1925), an anatomist and a histologist, after teaching first in his own University of Kharkov became Professor of Histology, discovers a new type of cells (Kulchitsky's Cells) in the epithelium of the small intestine (published in Archive für mikroskopische Anatomie). Later was appointed Director of Education in Kazan and in 1915 went to St. Petersburg. After the revolution came to England and worked at University College, in London..
1897 Thèse de Médecine of Ernest Duchesne (1874-1912): "Contribution à l’étude de la concurrence vitale chez les micro-organismes : antagonisme entre les moisissures et les microbes" between Penicillium and bacteria shows the antibiotic properties of certain molds.
1897 Ronald Ross (Almora, India 1857 - 1932) elucidates the life-cycle (alternation of generations) of Plasmodium (the malarial agent) in the body of its two hosts, a blood warmed vertebrate and a mosquito.
1897-1898 Carl Benda (1857-1933) develops a new staining method which allows him to identify Altmann's bioblasts, which he renames mitochondria (from mitoV: thread, and condroV: granule) and Camillo Golgi describes Golgi bodies in great detail and name them. What is now known as the Golgi apparatus had been 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.
1898 John Newport Langley (Newbury 1852 - 1925) works on nerve conduction, by blocking neuron functioning by nicotine. He discriminates between the Central Nervous System, and the autonomous nervous systems.
1998 Edmund Beecher Wilson (1856-1939) presents a famous lecture wherein he concluded that all spiralians - molluscs, flatworms, annelids, and nemerteans - share a common evolutionary ancestry.
1898 Arthur Croft-Hill (1863-1947) produces the first enzymatic synthesis, that of isomaltose.
1898 Sherrington describes rigidity in the decerebrate cat.
1898 Charles Reid Barnes (1858-1910) coins the term "photosynthesis."
1898 Karl Gegenbaur, after having worked on invertebrates, investigates the evolution of the egg, trying to substantiate darwinism through comparative anatomy. He summarizes his study of the skeleton in his treaty Vergleichende Anatomie der Wirbeltiere: mit Berucksichtigung der Wirbellosen. Using Huxley's dogmatic style he ridicules the idea that the skull is composed of vertebrae showing that there is continuous evolution of the cranium from sharks to humans. Investigation in homology with a phylogenetical purpose is the aim of his research.
1898 Edward Lee Thorndike (1874-1949) describes the puzzle box for experiments in psychology.
1898 Plague epidemic in Nhatrang. Yersin stops the spreading of the disease.
1898 Sergey Gavrilovich Navashin (1857-1930) and Léon Guignard discover independently the developmental origin of endosperm from double fertilization in angiosperms.
1898 Angelo Ruffini (Arquata del Tronto 1864 - 1929) using gold chloride identifies encapsulated nerve endings later known as Ruffini corpuscles.
1898 Walther Flemming determines the chromosome number as 24 pairs in Man.
1898 Henry Fairfield Osborn (1857-1935) enunciates the concept of adaptive radiation in evolution. This leads him slowly to support eugenist theories.
1898 André Thiroux (1869-1960) creates the Institut Bactériologique in Tananarive, that became the Institut Pasteur de Madagascar in 1927.
1898 The French veterinarian and physician C Besnoit (?-?) and Charles Morel (?-?) describe an unusual disease in sheep, tremblante, known as scrapie in English, the first type of known spongiform encephalopathies in Note sur les lésions nerveuses de la tremblante du mouton
1898 Martinus Willem Beijerinck (Amsterdam, 1851 - 1931) surmises that the tobacco mosaic causing agent is an infectious agent (contagium vivum fluidum), which he calls a virus.
1898 Löffler and Paul Frosch (1860 - 1928) make the same observation but in animals, with foot-and-mouth disease.
1898 The Bayer Drug Company markets heroin as a "non-addictive" anti-cough medicine.
1898-1904 Walter Bradford Cannon (1871 - 1945) uses X-rays to study the movements of the digestive system.
1899 Francis Gotch (1853 - 1913) describes a "refractory phase" between nerve impulses.
1899 August Bier (1861 -1949) uses cocaine for anesthesia of the spinal cord.
1899 William Bate Hardy (1864 - 1934) points out that many of the appearances of cytoplasm are artifacts of the staining and fixing methods that were employed; therefore, the existence of cytoplasmic structures should be confirmed by alternative methods.
1899 An International Congress on Plant Hybridization is held in London as Mendelian principles gain rapid acceptance. This is sometimes recognized as the birth of Genetics.
1899 Conwy Lloyd Morgan pursues his work in experimental psychology, comparing a variety of animals, in Introduction to comparative psychology.
1899 Jacques Loeb (Mayen 1859 - New York 1924) after a couple of years at the Stazione zoologica in Napoli succeeds (following Roux) in bringing about the development of sea urchin larvae from unfertilized eggs by exposing them to controlled changes in their environment. Much of his experimental work was done at the Marine Biological Laboratory at Woods Hole.
1899 Creation in Saïgon of an Institut Antirabique, together with an Institut Vaccinogène and a bacteriology laboratory. In these institutes, which later formed the Institut Pasteur de Paris of Saïgon, snakes are collected en masse to prepare immune sera.
1899 David Hilbert (Königsberg 1862 - Göttingen 1943) publishes his Grundlagen der Geometrie which has the greatest influence in this domain since Euclid.
1899 Karl Blossfeldt (1865 - Berlin 1932) begins a long career, with photographs of plants by the thousands - photographs which feature flowers, buds, branched stems, clusters or seed capsules shot directly from the side, seldom from an overhead view, and rarely from a diagonal perspective.