Jenner's indebtedness to John Hunter. Jenner's early observations
in natural history. He hears a countrywoman say, "I can't
take small-pox for I have had cow-pox." This sets him thinking.
He finds that of various forms of cow-pox but one gives
protection against small-pox. In 1796 successfully vaccinates
a patient. Holds that small-pox and cow-pox are modifications
of the same disease and that if the system be impregnated
with the milder disease, immunity from the severer is conferred.
Immense saving of life by vaccination.
Pasteur, a chemist, studies fermentation, which is due to
the rapid multiplication of organisms. Similar organisms he
detects as the cause of the silkworm disease and of anthrax
in cattle. He adopts the method of Jenner, prepares an
attenuated virus and protects cattle from anthrax. 25