CONCLUSION OF LETTER ON DUCKWEED 285 
water: and among many kinds of creatures, I saw some as 
big as sand-grains, which had as perfect a structure as our 
garden spiders.’ 
Here, Gentlemen, you have the notes that I have kept 
about my observations on duckweed and little animalcules: 
in making which I said to myself, How many creatures 
are still unbeknown to us, and how little do we yet 
understand ! 
The foregoing letter contains recognizable descriptions of 
at least five different Cillates—Vorticella, Carchesiwm, 
Cothurnia, Trichodina, and Kerona—all of which were first 
observed by Leeuwenhoek. He had, of course, described the 
Vorticellids at an earlier date, since when others had repeated 
his observations: and he had also, as we have already seen, 
previously observed the conjugation of freshwater ciliates— 
here mentioned again. But the letter is, nevertheless, full of 
protozoological novelties. 
Little more than a month later Leeuwenhoek sent the 
Royal Society another remarkable letter, which contained a 
description of the curious colonial flagellate Anthophysa 
vegetans—one of the “iron-protozoa.” This letter has been 
generally overlooked by protozoologists, and nobody hithert ° 
appears to have identified the organism described. The 
identification is, however, easy and certain. Only one inter- 
pretation of Leeuwenhoek’s description and figures is possible. 
I will now give a translation of the relevant passages in this 
highly interesting letter: ° 
' Probably water-mites. 
2 0. F. Miller, who rediscovered and named this flagellate (Volvor 
vegetans O.F.M., 1786; p. 22, Pl. III, figs. 22-25), was apparently ignorant 
of L.’s earlier observations.—I am aware that Anthophysa is mentioned 
among L.’s discoveries in the ‘ Leeuwenhoek Film” recently exhibited in 
Holland: but this mention was taken from my own note (1923), in which 
T attributed the discovery to L. without specific reference to the letter here 
translated. 
* Letter dated 5 February 1703. To the Royal Society. MS.Roy.Soc. Not 
published in Dutch or Latin Works. English translation (almost complete) 
published in Phil. Trans. (1703), Vol. XXIII, No. 286, pp. 1430-1443. 
The MS. of this translation is preserved along with the Dutch original, and 
is in the hand of John Chamberlayne. The above is a new translation 
(from the MS.) of a part of the letter only.—Vandevelde (1924, p. 133) calls 
this letter “ Brief 2 Tr 4 [148] ”’; but according to my numeration it is 
Letter 150. 
