THE EXPERIMENTS. 231 



Leeuwenhoek, fpeaking of the fpermatic ani- 

 mals of man *, fays : ' Aliquando etiam ani- 



* madvcrti inter animalcula paiticulas quafdam 



* minores etfubrotundas ; cum vero fe ea aliquo- 

 ' ties eo modo oculis meis exliibuerint, ut mihi 



* imaginarer eas exiguis inftrudas elTe caudis^ 



* cogitare coepi annon hae forte particulae fo- 



* rent animalcula recens nata ; certum enim mihi 



* eft ea etiam animalcula per generationem pro- 



* venire, vel ex mole minufcula ad adultam pro- 



* cedere quantitatem : Et quis kit annon ea 

 ' animalcula, ubi moriuntur, aliorum animalcu- 



* lorum nutritioni atque augmini inferviant !' It 

 appears from this paliage, that Leeuwenhoek had 

 feen, in the human femen, animalcules without 

 tails ; and that he is obliged to fuppofe them to 

 be recently produced, which is diredly the re- 

 verfe of what 1 have obferved ; for the moving 

 bodies are never larger than when they feparate 

 from the filaments, which is the period when their 

 motion begins : But, as foon as they are fully dif-^ 

 engaged from the mucilage, they become fmaller, 

 and continue to diminifli till their motion entire- 

 ly ceafes. With regard to the g«rneration of thefe 

 animals, which Leeuwenhoek imagines to be cer- 

 tain, no vellige of copulation has been difcerned 

 by the moft acute obfervers* It is purely a ran- 

 dom aflertion, as may be eafily proved from his 

 own experiments. He remarks, for example, 



with 

 * Tom. 3. p. 93. 



