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164 LEEUWENHOEK AND HIS “ LITTLE ANIMALS” 
of protozoology. Had it been published in his lifetime, it would 
have assured him a place in the very forefront of the founders 
of the science. Even at the present moment the excellence 
and originality of his observations have been largely obscured 
by his modern editors. In my opinion most of the protozoa 
described and roughly sketched by Huygens can be easily 
recognized by any competent protozoologist, yet his editors 
have not only failed to recognize the majority but have often 
misidentified common species most ludicrously. As examples, 
I may note that Huygens’s unmistakable account of Chilodon 
(with figures, including a characteristic pair in conjugation) 
is interpreted as “ probably infusoria of the genus Bursaria”’: 
his description of Astasia, with its characteristic euglenoid 
movements and “ hardly any colour”’, is said to suggest the 
bright green and rigid Phacus—“ if having hardly any colour 
be not taken to exclude a slight green coloration’: and so on. 
But we are here concerned with Leeuwenhoek—not with 
Huygens—so I shall say no more on this matter now. I 
hope to deal with Huygens’s admirable observations on another 
occasion. 
Whilst Leeuwenhoek’s astonishing researches were being 
considered by the Royal Society, he himself was continuing 
them and was corresponding with Constantijn Huygens (pater) 
about his discoveries. Sir Constantijn was also in frequent 
communication with his son Christiaan, at Paris, to whom he 
reported Leeuwenhoek’s findings. Christiaan, at first sceptical, 
soon repeated and confirmed the experiments: and at the end 
of 1678 he wrote a most interesting letter,’ accompanied by a 
few sketches, to his elder brother Constantijn. In this letter 
Christiaan gave unmistakable’ descriptions of Chzlodon, 
Paramecium, Astasia, and Vorticella—all found in infusions: 
and he added “I should much like to know what Leeuwenhoek 
would say about all this, and whether he has seen anything 
like them.” Evidently the letter was sent to Leeuwenhoek, 
who wrote to Constantijn Huygens sen. about it a little later.’ 
" Chr. Huygens to Const. Huygens jun. 18 Nov. 1678. Printed in 
Guvres Compl. Vol. VIII (1899), No. 2148, p. 122. 
* To me they are all unmistakable in this description: and when the 
notes of 26 July 1678 (published in Guvr. Compl. XIII (ii), 702) are also 
taken into account, the identifications are surely beyond all doubt. 
* Leeuwenhoek to Const. Huygens sen. 26 Dec. 1678. Letter printed in 
Gwor. Compl. VIII, No. 2156, p. 140. 
