Edition 360f2c85 · generated from Tabula content · 6 plates
Fits: Biology (cells, tissues); nature of science
Licence: photocopiable for classroom use by the purchaser (single teacher), or across one school with a school licence.
The body as known in 1661. Colour what was understood; outline what was only described.The body as known in 1800. Colour what was understood; outline what was only described.The body as known in 1921–22. Colour what was understood; outline what was only described.The body as known in 1888–89. Colour what was understood; outline what was only described.
Story cards
Tab. XVII: The missing link (1661)
Through a microscope, in a frog's lung, the vessels Harvey needed but never saw.
How they knew: Microscopy of thin, transparent frog lungs, first dead and then living, with the help of his colleague Carlo Fracassati.
What it overturned: The idea that blood seeps from arteries to veins through the "porosities" of the flesh, and the old view of the lung as a solid, fleshy organ.
Status: established
Tab. XIX: A student saw them first (Aug–Nov 1677)
Living "animalcules" in semen, and an unusually honest attribution.
How they knew: Single-lens microscopes of extraordinary power, ground by Leeuwenhoek himself.
What it overturned: Ham's own first guess that the moving particles were a product of decay, and the assumption that semen was a uniform fluid.
Status: established
Tab. XX: Twenty-one tissues, no microscope (1800)
Bichat stops thinking in organs and starts thinking in tissues.
How they knew: Naked-eye study of organs by their physical properties (texture, elasticity, transparency, reaction to injury), plus hundreds of autopsies.
What it overturned: The habit of treating each organ as a single indivisible unit of anatomy and disease.
Status: established
Tab. XXI: Seen in 1869, understood in 1921 (1869)
A medical student spots strange clusters of cells in the pancreas and doesn't know what they are.
How they knew: Microscopy of stained pancreatic tissue for a doctoral dissertation.
What it overturned: The view of the pancreas as a single, uniform digestive gland.
Status: established
Tab. XXIII: What the islets do (1921–22)
An extract from the pancreas brings down blood sugar, and starts a bitter fight over credit.
How they knew: Experiments on dogs with diabetes, followed by purification of a pancreatic extract good enough to treat human patients.
What it overturned: The idea that the pancreas works only as a digestive gland, and that diabetes was untreatable.
Status: contested. The science is not in doubt; the credit is. The 1923 Nobel Prize went to Banting and Macleod. Banting shared his prize money with Best, and Macleod shared his with Collip.
Tab. XXII: Using Golgi's stain against Golgi (1888–89)
The nervous system is made of separate cells, not one continuous net.
How they knew: An improved version of Golgi's silver-chromate stain, which blackens a few whole nerve cells at random, applied to young birds' brains and retinas, and recorded in thousands of drawings.
What it overturned: The reticular theory, defended by Golgi, that the nervous system is a single continuous network.
Status: established
Spot the myth
For each statement, decide: was it believed then, later overturned, or is it supported by the sources?
Nerve fibres fuse into a single continuous network rather than being made of separate cells.
In two letters to Giovanni Alfonso Borelli printed at Bologna in 1661, Malpighi showed with a microscope that the lung is made of tiny air sacs rather than solid flesh.
In August 1677 the medical student Johan Ham showed Leeuwenhoek small moving "animalcules" he had seen in semen; Leeuwenhoek recorded that Ham had seen them first.
Discussion questions
Marcello Malpighi: what method did they use, and why did it convince (or fail to convince) people at the time?
What did people believe before Tab. XVII, and why was that belief reasonable then?
Johan Ham and Antonie van Leeuwenhoek: what method did they use, and why did it convince (or fail to convince) people at the time?
What did people believe before Tab. XIX, and why was that belief reasonable then?
Xavier Bichat: what method did they use, and why did it convince (or fail to convince) people at the time?
What did people believe before Tab. XX, and why was that belief reasonable then?
Paul Langerhans: what method did they use, and why did it convince (or fail to convince) people at the time?
What did people believe before Tab. XXI, and why was that belief reasonable then?
Answer key and sources
believed then, later overturned [reticular-theory#b]
supported by the sources [malpighi-capillaries#c1]
supported by the sources [ham-leeuwenhoek-spermatozoa#c1]
Every claim in this pack
[malpighi-capillaries#c1] In two letters to Giovanni Alfonso Borelli printed at Bologna in 1661, Malpighi showed with a microscope that the lung is made of tiny air sacs rather than solid flesh. (established). Sources: Marcello Malpighi, De pulmonibus observationes anatomicae (two letters to Borelli) (1661); Luca Tonetti, Frogs' lungs and Malpighi's discovery of pulmonary capillaries (2015); University of Bologna (Scienza Giovane), Malpighi (continued) (n.d.)
[malpighi-capillaries#c2] Working on frogs with the help of Carlo Fracassati, he observed blood moving through minute vessels connecting arteries and veins in the lung, which Harvey had inferred but never seen. (established). Sources: Marcello Malpighi, De pulmonibus observationes anatomicae (two letters to Borelli) (1661); Luca Tonetti, Frogs' lungs and Malpighi's discovery of pulmonary capillaries (2015); University of Bologna (Scienza Giovane), Malpighi (continued) (n.d.)
[ham-leeuwenhoek-spermatozoa#c1] In August 1677 the medical student Johan Ham showed Leeuwenhoek small moving "animalcules" he had seen in semen; Leeuwenhoek recorded that Ham had seen them first. (established). Sources: Antonie van Leeuwenhoek, Alle de brieven van Antoni van Leeuwenhoek (collected letters) (1939–); Royal Society Archive catalogue, Leeuwenhoek letter on spermatozoa, 1677 (EL/L3/7) (n.d.)
[ham-leeuwenhoek-spermatozoa#c2] Leeuwenhoek reported the observations to the Royal Society in November 1677; the original letter is lost, but a translation was printed in the Philosophical Transactions. (established). Sources: Antonie van Leeuwenhoek, Observationes de natis e semine genitali animalculis (Philosophical Transactions 12, no. 142, p. 1040) (1677); Royal Society Archive catalogue, Leeuwenhoek letter on spermatozoa, 1677 (EL/L3/7) (n.d.); Antonie van Leeuwenhoek, Alle de brieven van Antoni van Leeuwenhoek (collected letters) (1939–)
[bichat-tissues#c1] In his Traité des membranes (1800), Bichat argued that organs are built from a limited number of distinct tissues, and distinguished 21 kinds. (established). Sources: Xavier Bichat, Traité des membranes en général et de diverses membranes en particulier (1800); University of Iowa, Heirs of Hippocrates, Bichat, Traité des membranes (record 1256) (n.d.); (article, PubMed Central), [Article on Xavier Bichat and the Traité des membranes] (n.d.)
[bichat-tissues#c2] He worked with the naked eye, distinguishing tissues by properties such as texture, elasticity and transparency, and did not use the microscope. (established). Sources: (article, PubMed Central), [Article on Xavier Bichat and the Traité des membranes] (n.d.); University of Iowa, Heirs of Hippocrates, Bichat, Traité des membranes (record 1256) (n.d.)
[langerhans-islets#c1] In 1869 Paul Langerhans described distinct clusters of cells in the pancreas in his doctoral dissertation; they were later named the islets of Langerhans. (established). Sources: Paul Langerhans, Beiträge zur mikroskopischen Anatomie der Bauchspeicheldrüse (1869); Royal Society of Biology, Insulin (Biology Changing the World stories) (n.d.); Endocrine Society, Endocrine Reviews, Insulin discovery 100th anniversary (2021)
[langerhans-islets#c2] Their role in producing insulin and regulating blood sugar was established only in the twentieth century. (established). Sources: Royal Society of Biology, Insulin (Biology Changing the World stories) (n.d.); Endocrine Society, Endocrine Reviews, Insulin discovery 100th anniversary (2021)
[insulin-islets-function#c1] At the University of Toronto in 1921–22, Frederick Banting and Charles Best, in J. J. R. Macleod's department, isolated a pancreatic extract that lowered blood sugar, and James Collip purified it for human use. (established). Sources: Royal Society of Biology, Insulin (Biology Changing the World stories) (n.d.); Endocrine Society, Endocrine Reviews, Insulin discovery 100th anniversary (2021); Dictionary of Canadian Biography, Collip, James Bertram (n.d.)
[insulin-islets-function#c2] The 1923 Nobel Prize in Physiology or Medicine went to Banting and Macleod; Banting shared his prize money with Best, and Macleod shared his with Collip. (contested). Sources: The Nobel Foundation, The Nobel Prize in Physiology or Medicine 1923 (1923); (article, PubMed Central), [Centenary article on the discovery of insulin] (2022); Dictionary of Canadian Biography, Collip, James Bertram (n.d.)
[cajal-neurons#c1] Using a modified version of Golgi's stain, Cajal showed in studies of the bird cerebellum and retina in 1888–89 that nerve cells are separate units rather than a continuous network. (established). Sources: Santiago Ramón y Cajal, Estructura de los centros nerviosos de las aves (1888); CSIC (Spanish National Research Council), Santiago Ramón y Cajal (1852–1934), the Cajal Legacy (n.d.); Scientifica, Meet the Nobels: Golgi and Cajal (n.d.)
[cajal-neurons#c2] Golgi and Cajal shared the 1906 Nobel Prize in Physiology or Medicine; in his Nobel lecture Golgi still defended the reticular theory. (established). Sources: The Nobel Foundation, The Nobel Prize in Physiology or Medicine 1906 (Golgi and Cajal), with Nobel lectures (1906); Scientifica, Meet the Nobels: Golgi and Cajal (n.d.); CSIC (Spanish National Research Council), Santiago Ramón y Cajal (1852–1934), the Cajal Legacy (n.d.)
[cajal-neurons#c3] The neuron doctrine was given its name by Wilhelm Waldeyer in 1891, and electron microscopy later showed that a membrane encloses each neuron. (established). Sources: Scientifica, Meet the Nobels: Golgi and Cajal (n.d.); CSIC (Spanish National Research Council), Santiago Ramón y Cajal (1852–1934), the Cajal Legacy (n.d.)
[reticular-theory#b] Camillo Golgi defended the reticular theory of a continuous nervous network, still doing so in his 1906 Nobel lecture. (established). Sources: The Nobel Foundation, The Nobel Prize in Physiology or Medicine 1906 (Golgi and Cajal), with Nobel lectures (1906); Scientifica, Meet the Nobels: Golgi and Cajal (n.d.); CSIC (Spanish National Research Council), Santiago Ramón y Cajal (1852–1934), the Cajal Legacy (n.d.)
[reticular-theory#c] Cajal showed in 1888–89 that nerve cells are separate units, and by the early 1890s most scientists accepted the neuron doctrine. (established). Sources: Santiago Ramón y Cajal, Estructura de los centros nerviosos de las aves (1888); CSIC (Spanish National Research Council), Santiago Ramón y Cajal (1852–1934), the Cajal Legacy (n.d.); Scientifica, Meet the Nobels: Golgi and Cajal (n.d.)