156 
1 
LEEUWENHOEK AND HIS “ LITTLE ANIMALS ’”’ 
that I did not examine it from day to day, and kept no 
note of when I last added water thereunto: on this date 
I discovered very many living creatures, which displayed 
themselves, through my microscope, as no bigger than an 
ordinary sand-grain to the naked eye. These were very 
clear, and seemed to be about twice as long as broad. 
Along with them were some few animalcules which looked 
as big as ordinary ant-eggs’; the upper part of their body 
being round and raised, the under part flat, like unto 
tortoises in shape. ‘Their whole body seemed to be made 
up of no other parts than big and little globules, which 
were all very glittering, so long as the animalcules were 
alive: but when I brought them into a dry place (where- 
upon they oft-times burst asunder), the glittering went 
off; and the globules became smaller, and flowed away 
on all sides, together with some watery humour in which 
these globules lay. These animalcules were provided 
underneath the body with divers little legs, whereof 5 or 6 
stuck out in front of the head during motion. 
The 14th ditto, I discovered many more animalcules 
than heretofore, but most of them were very small. 
The 19th ditto, I discovered, besides the said creatures, 
many animalcules with tails,” along with many long 
animalcules that were fashioned aslant in front; and if I 
saw aright, their hindmost part was somewhat cloven, 
their body flat below and round above, their length well 
anigh that of the little oval animals. 
The 4th of August, I did not perceive the long 
animalcules, but exceeding many very little animalcules, 
and some few that were a bit bigger. The water being 
now almost evaporated away, I added well-water to it. 
i.e., they appeared, through the microscope, about as big as “ ant-eggs”’ 
appear to the naked eye. (In a later letter L. showed that the structures 
commonly called “ ant-eggs’’ are not really the ova of the ant, but its pupae. 
Cf. Letter 58, 9 Sept. 1687.) From the deseription which follows, they 
were obviously hypotrichous ciliates: but it is impossible to identify them 
more precisely. 
* i.e., some species of Vorticella. Cf. p. 118. 
