TabulaThe body, as it was written.

A tour · 6 plates

Seeing the invisible

This tour is about what changed when anatomists could see below the naked eye, and about a gap that the fog on this site is built to show: the gap between seeing a structure and understanding it. In 1661 Malpighi's lens found the vessels between arteries and veins that Harvey had predicted.1 In 1677 a medical student, Johan Ham, showed Leeuwenhoek moving cells in semen, and Leeuwenhoek said so.2 In 1800 Bichat argued that organs are built from a limited set of tissues, and he did it without a microscope.3 In 1869 Langerhans described clusters of cells in the pancreas, but their role in making insulin was established only in the twentieth century.4 Cajal used a silver stain to show that nerve cells are separate units.5 Watch the outlines on the body: on this tour, colour usually arrives later than the line. Sometimes the wait was half a century.

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  1. Tab. XVII: The missing link (1661)
  2. Tab. XIX: A student saw them first (Aug–Nov 1677)
  3. Tab. XX: Twenty-one tissues, no microscope (1800)
  4. Tab. XXI: Seen in 1869, understood in 1921 (1869)
  5. Tab. XXIII: What the islets do (1921–22)
  6. Tab. XXII: Using Golgi's stain against Golgi (1888–89)

Sources for this introduction

  1. Harvey inferred but never saw the connection between arteries and veins; in 1661 Malpighi, with Carlo Fracassati, observed blood in minute vessels of the frog lung.

    • Marcello Malpighi, De pulmonibus observationes anatomicae (two letters to Borelli). 1661. Bologna. primary
    • Luca Tonetti, Frogs' lungs and Malpighi's discovery of pulmonary capillaries. 2015. Acta Phlebologica 16(1):41–51. Link · Archive scholarly
    • University of Bologna (Scienza Giovane), Malpighi (continued). n.d.. Link · Archive scholarly

  2. In August 1677 the medical student Johan Ham showed Antonie van Leeuwenhoek moving 'animalcules' in semen; Leeuwenhoek reported them to the Royal Society that November and recorded that Ham had seen them first.

    • Antonie van Leeuwenhoek, Alle de brieven van Antoni van Leeuwenhoek (collected letters). 1939–. Link · Archive primary
    • Royal Society Archive catalogue, Leeuwenhoek letter on spermatozoa, 1677 (EL/L3/7). n.d.. Link · Archive scholarly
    • Antonie van Leeuwenhoek, Observationes de natis e semine genitali animalculis (Philosophical Transactions 12, no. 142, p. 1040). 1677. primary

  3. In his Traité des membranes (1800), Xavier Bichat argued that organs are built from a limited set of tissues, distinguished 21 kinds, and worked without a microscope.

    • Xavier Bichat, Traité des membranes en général et de diverses membranes en particulier. 1800. Paris. primary
    • (article, PubMed Central), [Article on Xavier Bichat and the Traité des membranes]. n.d.. Link · Archive scholarly · details pending
    • University of Iowa, Heirs of Hippocrates, Bichat, Traité des membranes (record 1256). n.d.. Link · Archive scholarly

  4. In 1869 Paul Langerhans described distinct clusters of cells in the pancreas, later named the islets of Langerhans, whose role in producing insulin was established only in the twentieth century.

    • Paul Langerhans, Beiträge zur mikroskopischen Anatomie der Bauchspeicheldrüse. 1869. Berlin. primary
    • Royal Society of Biology, Insulin (Biology Changing the World stories). n.d.. Link · Archive scholarly
    • Endocrine Society, Endocrine Reviews, Insulin discovery 100th anniversary. 2021. Link · Archive scholarly

  5. Cajal used an improved version of Golgi's stain, which blackens a few whole nerve cells, to show in 1888–89 that nerve cells are separate units.

    • Santiago Ramón y Cajal, Estructura de los centros nerviosos de las aves. 1888. Revista Trimestral de Histología Normal y Patológica. primary
    • CSIC (Spanish National Research Council), Santiago Ramón y Cajal (1852–1934), the Cajal Legacy. n.d.. Link · Archive scholarly
    • Scientifica, Meet the Nobels: Golgi and Cajal. n.d.. Link · Archive secondary