320 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1944 
Columbus are credited with discovering continents, but Leeuwenhoek 
opened the door to an entire new world. Wherever he looked—in 
soil, water, food, excretions, or decaying materials—he discovered 
a host of micro-organisms that nobody had ever seen before or even 
suspected of existing. Modern explorers with electron microscopes 
are having a great time too, but their discoveries of molecules and 
viruses and of the minute anatomy of bacteria is hardly to be com- 
pared with the new world that Leeuwenhoek found under his 
microscope. 
But I do not think that knowledge of the existence of insects makes 
an entomologist, or knowledge of the existence of stars an astronomer, 
so I hesitate to consider Leeuwenhoek the father of bacteriology. 
That honor, I think, should go to Pasteur who, within the lifetime 
of my parents, made bacteriology a science. He did it by providing 
final proof that germs, like all other forms of life, require parents, 
and come only from pre-existing germs. As long as it was thought 
that germs developed spontaneously from decomposing materials the 
bacteriologist was in as hopeless a position scientifically as a mathe- 
matician would be if the sum of two and two varied with the weather. 
From the standpoint of the control and prevention of disease this 
was undoubtedly the most momentous discovery ever made by man, 
for it alone provided a solid foundation for practically all our public 
health work. On it rests all our theory and practice concerning 
contagion and infection, quarantine, sterilization, antisepsis, aseptic 
surgery, purification of water, pasteurization of milk, and almost 
everything else on which modern practices of public health and hygiene 
are based. Pasteur is rightly revered for his great contribution in 
proving the germ theory of disease, but this would have been of little 
value or significance without the final abolition of the idea of spon- 
taneous generation, which for a long time extended even to maggots 
and mice. 
Pasteur’s fundamental discoveries led almost at once to practical 
applications. Lister in London was quick to apply them to surgery, 
and by very generous application of carbolic acid to himself, the pa- 
tient, the bedclothes, the air, and even the floor, be brought about a 
very considerable reduction in the mortality from operations, which 
had previously been about 45 percent even in his expert hands. 
During the eighteenth century Europe suffered from great epi- 
demics of childbed fever—at one time it got so bad that in Lombardy 
it was said that for a year not one woman lived after bearing a child. 
Europe’s lying-in hospitals for destitute mothers were humane in 
spirit only; in reality they were death traps. Oliver Wendell Holmes 
proclaimed childbirth fever an infectious disease, carried from patient 
to patient by physicians and midwives. Many physicians were in- 
censed at the imputation that their hands were not clean, and Holmes’s 
