296 LEEUWENHOEK AND HIS “LITTLE ANIMALS” 
large animalcules, mixt with very’ many air-bubbles, of 
extreme littleness. 
A few days’ afterwards, I asked to have a little of this 
water brought to my house, in order to examine it more 
nicely ; but I could discover nothing else in it than what 
I have just related, though I noticed a little later that 
no air-bubbles * were to be seen in it. 
Now if people rinse beer and wine glasses in such a 
pond, who can tell how many animalcules may be left in 
these glasses ? whence some of them may even get into 
our mouths. And this being so, people have no reason 
to ask me how the little animalcules, which, as I have 
said many a long year ago,’ are in the stuff between our 
teeth, and in hollow grinders,’ are able to get there. 
Thus far my notes, which I kept some years ago, and 
which I have come across within these last few days. 
Leeuwenhoek’s last recorded observations on protozoa are 
contained in a letter written in 1716 to Boerhaave.° Unfor- 
tunately they are mentioned very briefly—being sandwiched 
in between observations and speculations on spermatozoa. 
Despite their brevity, however, they are of extreme interest. 
After speaking of the spermatozoa of various animals, 
Leeuwenhoek abruptly interjects the following remarks: ‘ 
1 The word “very” (seer) is in the printed version, but not in the MS. 
* Eenige dagen MS. Eenige weynige dagen Dutch printed version. 
* Lugtbellen [underlined] in MS. The printed version has lugtbolletjes. 
* Vide p. 238 sq., supra. The “ animalcules”’ were, of course, bacteria. 
° inde stoffe . . . tussen onse tanden, ende inde holle kiesen [last 
two words underlined] MS. “in and about our Teeth” Phil. Trans. 
There are slight verbal differences here between the Dutch printed version 
and the MS., though the sense does not differ. 
®° Herman Boerhaave (1668-1738), Professor of Botany, Chemistry, 
and Medicine at Leyden— ‘a whole Medical Faculty in himself’’—is too 
famous a character to need further annotation. He was elected a Fellow of 
the Royal Society in 1730. For his life see especially Banga (1868, p. 807) 
and N. Nederl. Biogr. Woordenb. (1924), VI, 127 [a long and excellent article 
by van Leersum J. 
” From Letter XXIX. 5 November 1716. To Boerhaave. Published 
in Brieven, Vol. IV, p. 284; and (in Latin) in Opera Omnia, Vol. IV 
(Epist. Physiol.), p. 279. No MS., and not in Phil. Trans.—The passage 
here translated begins on p. 288 of the Dutch edition. 
