The 19th-century veterinarian who nearly cracked one of medicine’s oldest mysteries
As far as presenting the case for germ theory, James Law’s 45-page report “Influenza in Horses,” which appeared in the Report of the Commissioner of Agriculture for the Year 1872 was a tour de force of the medical geography of the Great Epizootic. It contained detailed information on the “atmospheric conditions” that miasmists turned to over and over again, as well as a synopsis of the results of a study Law had commissioned from a microscopist colleague. It was from that combination of medical geography, meteorological data, and microscopy from which Law drew many of his conclusions. [Editor’s Note: Miasma theory is the now-debunked belief that vapors found in “bad air” caused diseases. During the second half of the 19th century, it competed with germ theory as the best explanation for illnesses and epidemics.] Law begins his report with a lengthy history of epidemics in humans and epizootics in animals from the time of the ancient Greeks onward, followed by a medical geography of the Great Epizootic. Next, he spends page after page describing the …






