OBSERVATIONS ON RAIN-WATER O15 
and that the air-bubbles might keep the position that 
they had at the top of the glass; and after the lapse of 
ten hours I saw a great many air-bubbles, that were 
mostly affixed to the said dust-particles. And forasmuch 
as we know that no dry matter or any other particles, in 
which air is included, when they get under water can 
then get the water into them unless the air be first dis- 
lodged, so the same held good also for the particles that 
were in the glass tube. 
But what is one to say of this, that some of the air- 
bubbles were quite a hundred (and others several hundred) 
times bigger than the particles on which they were 
stuck ? 
Next day, in the morning, I perceived no more than 
four very little air-bubbles, and a few hours afterwards I 
couldn’t find a single one. 
I examined this water every day till the 14th of 
November, but could discover no living creature in it; 
and the day after, I had the mischance to let my tube 
drop, so that it was smashed to bits.’ 
It is not possible to identify the organisms mentioned in 
the foregoing letter, though some of them must certainly have 
been protozoa. At the end of the year, however, Leeuwenhoek 
wrote a very important epistle in which he described and 
figured several freshwater protozoa which are easily recog- 
nizable. This letter is so important, indeed, that I must 
translate almost the whole of it. It is addressed to the Royal 
Society, and runs as follows: ’” 
1 The remainder of this letter deals with other subjects, and is therefore 
omitted. 
2 Letter dated 25 December 1702. To the Royal Society. MS.Roy.Soc. 
Not printed in Dutch or Latin editions. English translation in Phil. Trans. 
(1703), Vol. XXIII, No. 283, pp. 1304-1311. (The MS. of this translation 
is also extant, and is in the hand of John Chamberlayne. See p. 270, 
note 2, supra.) According to my numeration this is Letter 149. Vandevelde 
numbers it ‘‘ Brief 2 Tr 3 [147] ”.—I have made my translation from the 
original Dutch MS., but have compared it with Chamberlayne’s and note 
one or two points in which his version differs. 
