368 LEEUWENHOEK AND HIS “‘ LITTLE ANIMALS ”’ 
epidemics. Iwish such authors would also explain, in modern 
terms, what Kircher meant when he recorded further how 
plague could arise likewise from a rotting mermaid. 
For my part, I cannot regard Kircher as anything more 
than the veriest dabbler in Science. His own writings 
appear to me unscientific in the highest degree, and I can find 
no evidence that he ever saw—even by chance—a protozoon 
or a bacterium through his “smicroscope.” His writings 
appear, consequently, to furnish no evidence whatsoever to 
prove that he forestalled Leeuwenhoek. But asI have already 
said, I have not read all his works. I can therefore only beg 
his supporters (if any there still be) to adduce some solid 
passage—which I have hitherto been unable to discover in his 
vast publications—to prove that he ever saw a protozoon. 
(Discussion of his “ discovery’ of the Bacteria may well be 
postponed until it has been demonstrated that he observed 
these larger organisms.) I am aware, of course, that Garrison * 
calls Kircher “the earliest of the microscopists”’ and says 
that he was “ undoubtedly the first to state in explicit terms 
the doctrine of a ‘contagium animatum’ as the cause of 
infectious diseases”’: but I submit that these statements also 
have not yet been substantiated, and I cannot conceive that 
they ever will be. Microscopists and contagiwm animatum 
both existed before Kircher began to write. 
This brings us to another line of argument against 
Leeuwenhoek’s originality—the argument from the doctrine of 
contagium vivum. It is as certain as anything historic ever 
can be that Kircher was not the first exponent of this idea: 
and there can be no doubt that the part played by “ animal- 
cules” in the causation of diseases was foreshadowed long 
before either Kircher or Leeuwenhoek was born.’ Some of the 
oldest known authors appear to have been familiar with the 
1 Garrison (1921), p. 250. 
2 In this connexion the paper by Singer (1913) should be mentioned, 
though I must confess that I have been unable to verify many of his 
statements and references. 
3 IT do not deny, of course, that Kircher formulated a “ doctrine of 
contagium animatum’’—and possibly more explicitly than his predecessors : 
but I do deny that it had any more objective basis than similar earlier 
guesses. The doctrine had no concrete foundation before L.’s discovery of 
real “ animalcules.’’ 
