198 LEEUWENHOEK AND HIS “ LITTLE ANIMALS ”’ 
compressed by the air-bubbles which rose everywhere to 
the top of the water) escaped with force out of the tube: 
for which reason I rather fancied that there would be no 
living creatures in this water. But I found the contrary: 
for no sooner did I draw some water through the small 
opening I had made at G, and bring it before my micro- 
scope, than I perceived in it a kind of living animalcules 
that were round, and bigger than the biggest sort that I 
have said were in the other water, though they were yet 
so small that it was not possible for me to discern them 
through the thickness of the glass tube.’ After this tube 
had stood thus open for 24 hours, I examined the water 
again ; and I then saw, besides the foresaid animalcules, 
various other sorts, though they were so small that they 
were hard to make out. 
Still, I bethought me that when that Gentleman afore- 
said spake of living creatures”, he meant only worms or 
maggots, which you commonly see in rotten meat, and 
which ordinarily proceed from the eggs of flies, and which 
are so big that we have no need of a good* microscope to 
descry * them. 
The whole of the foregoing passage (as printed in Dutch) 
has recently been copied and learnedly commented upon by 
Prof. Beijerinck (1913), who himself repeated the experiments. 
He infers that the “animalcules”? which Leeuwenhoek dis- 
covered were undoubtedly bacteria—not protozoa—and that 
among them were probably (as he found in his own experiments) 
Bacillus coli, Azotobacter, and Amylobacter saccharobutyricum. 
It was to this last species, he thinks, that the “ bigger sort ”’ 
which were found in the sealed tube probably belonged. 
Beijerinck also points out that these are the earliest known 
observations on any anaerobic bacteria: but although 
' So in the printed version. The MS. has “ for reasons already men- 
tioned ”’ (voor de verhaelde oorsaeken). 
> dierkens MS. schepsels printed version. 
* goet is in printed version, but not in MS. 
* bekennen MS. beschowwen printed version. 
