382 LEEUWENHOEK AND HIS ‘‘ LITTLE ANIMALS ”’ 
tentative preliminary papers.’ His huge final treatise of 1838, 
together with its comparatively small but devastating corrective 
by Dujardin’ in 1841, forms the real foundation of modern 
Protozoology. But the first experimental work on trans- 
missible microbic diseases was probably that published in the 
same period by Bassi * (1835), while the first on any protozoal 
infection came much later from Pasteur (1870). Both of these 
experimenters studied, singularly enough, no well-known 
maladies of man, but certain obscure “epidemics” of silk- 
worms—“ moscardino”’ and “ pébrine”’ respectively.’ 
It is not my purpose now to trace the history of Proto- 
zoology and Bacteriology during the last hundred years, so I 
shall leave the subject at the moment when our modern sciences 
commenced. The authors I have mentioned, and the works 
which they performed, are chronicled merely to remind the 
reader of certain salient events which cannot be overlooked if 
we would see Leeuwenhoek in his true perspective and 
proportions. 
Of Leeuwenhoek’s discoveries in sciences other than 
Protistology I am not competent to speak. I observe, however, 
that he is usually most praised by those most qualified to judge. 
Those authors who decry his observations generally reveal 
themselves, at the same time, ignorant of himself and his 
works. Asan instance I may cite the opinions expressed by 
certain botanical writers. Two careful Dutch authors— 
van Hall (1834) and Bolsius (1903)—find much that is original 
and admirable in Leeuwenhoek’s studies of plants: but the 
more famous German botanist Sachs (1875), whose knowledge 
of Leeuwenhoek was obviously not profound, says that “ 
the whole, all his numerous communications, in comparison 
1 T possess and have studied all of these, though I do not cite them here. 
2 Félix Dujardin (1801-1860), Professor of Zoology at Rennes. For his 
life see Joubin (1901). I have also studied—though I do not cite—the 
earlier works of this admirable protozoologist. 
® Agostino Bassi (1773-1856), of Lodi. See his Opere (1925), recently 
reprinted and edited, with a remarkable introduction by the late Prof. 
B. Grassi; who sums up his review with the statement that “it is proved 
that parasitology, like many other branches of knowledge, had its cradle 
in our own Italy: foreigners have merely recognized and perfected it.” 
Nevertheless, no Italian saw protozoa or bacteria before the year 1674. 
* Moscardino is now supposed to be caused by a fungus (Botrytis) and 
pébrine by a protozoon (Nosema)—both of doubtful systematic status. 
