A pioneer in the field of microscopic anatomy and pathology, Friedrich Gustav Jacob Henle (1809–1885) made signal contributions to elucidating the structure of both healthy and diseased tissues. His discovery of the ascending and descending loops of the uriniferous tubule is central to understanding renal function, but the "loop of Henle" is just one of many anatomical structures carrying his name. Henle's recognition that all inner and outer surfaces of the body are lined with epithelial tissue has been called "one of the most momentous generalizations of the century" (Robinson, 1921), while his three-volume Handbook of Human Anatomy (1855–1871) is "considered by many authorities to be the greatest of the modern systems of anatomy" (Morton, 1965).
Epidemiologists celebrate Henle for his publication, in 1840, of Von den Miasman und Kontagien (On miasmata and contagia), which set out, more convincingly than previously, the concept that microscopic living organisms (Henle called them contagia animata) were the causative agents of many diseases, especially those that occurred in epidemic form. Henle argued that in communicable diseases morbid matter apparently increases in amount in the host, but only after a period of incubation, which must correspond to the period of reproduction of the agent. His work drew on the work of Agostino Bassi (1773–1856), who showed that the muscardine of silkworm was attributable to a specific fungus. He also drew on Schwann and Schleiden's discovery that all life had a cellular structure; Schwann and Cagniard-Latour's proof that fermentation by yeast was the work of a live organism; and the evident ability of certain morbid matters, such as vaccinia and variola lymph, to experimentally produce systemic effects in animals even when greatly diluted.
Henle's thinking, which provided a theoretical basis for germ theory, had affinities with earlier writings of Girolamo Fracastoro (1478–1553) and Athanasius Kircher (1601–1680), but was nevertheless resisted for decades. Yet he lived to see his student Robert Koch (1843–1910) demonstrate conclusively the role of specific bacteria in anthrax, tuberculosis, and cholera.
Morton, L. (1965). Garrison and Morton's Medical Bibliography: An Annotated Check-List of Texts Illustrating the History of Medicine, 2nd edition, revised. London: Andre Deutsch.
Robinson, V. (1921). The Life of Jacob Henle. New York: Medical Life Company.