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370 LEEUWENHOEK AND HIS “LITTLE ANIMALS ”’ 
all early speculations about the relation of “insects” to 
malaria belong properly to the -prehistory of entomology—not 
to that of protozoology. 
The whole history of bacteriology has recently been so 
admirably written by Bulloch (1930) that I can add nothing to 
his account of its origins.” He has shown quite clearly that 
real bacteriology (like real protozoology) began with Leeuwen- 
hoek’s discoveries, though it was preceded by a long period of 
speculation on the causes of contagious diseases. Some early 
writers, it is true, made astonishing guesses at the existence of 
bacteria—particularly Fracastoro (1478 or 1483—1553), whose 
hypothetic “ seminaria”’ bear a remarkable resemblance to 
modern ‘germs’ or “microbes”.? But nobody before 
Leeuwenhoek ever saw a bacterium with his own eyes. 
Nebulous though ingenious notions about invisible living 
organisms floated in the air for some thousands of years : but 
it required the untutored genius of a Leeuwenhoek to condense 
them—single-handed and with only his own little home-made 
‘““microscopes”’—into the concrete realities of present-day 
laboratories and text-books of bacteriology. 
Another point should not be overlooked in this connexion. 
When Leeuwenhoek announced his discovery of the 
“animalcules”” in various waters and infusions, it was 
universally regarded as something entirely new. Yet the 
earlier writings of Kircher and others had already been public 
property for some years. Why, then, were contemporary 
‘“ philosophers ’”’ astounded at Leeuwenhoek’s “ discoveries ”»— 
if they were not real discoveries? And why did some 
contemporary and later critics dispute his observations ? 
Why did no author of his time—including Kircher, who was 
still alive and busy writing—claim priority? It is surely 
strange, to say the least, that nobody before Loffler in 1887 
ever connected Leeuwenhoek’s concrete discoveries of 1676 
with Kircher’s random speculations and “experiments” of 1658. 
1 T may note, however, that I have studied most of the early writings 
mentioned in this fine and accurate work: but as I agree entirely with its 
conclusions, and as it has an authority far beyond anything to which I can 
pretend, I shall here dispense with all other references to the subject. 
2 I cite the work of Fracastoro because I have devoted particular atten- 
tion to his writings, owing to their great historic interest. On Fracastoro 
see also C. and D. Singer (1917). 
