THE EXPERIMENTS. 229 



* tinuo manent motii, et, tempore quo ipfis morl- 



* endum appropinquante, niotus magis magifque 

 ' deficit, ufqucdum nullus prorfiis motus in illis 

 ' agiiofccndiis lit.' It is difficult to conceive, 

 that animals fhould exift, which, from the mo- 

 ment of their birth to their diflblution, ihould 

 continue to move rapidly, without the fmalleft 

 interval of repofe ; or to imagine that the fper- 

 matic animals of the dog, which Leeuwenhoek 

 perceived to be as adive on the feventh day as 

 the moment they proceeded from the body of 

 the dog, fhould be able, during all this time, to 

 move with a celerity which no animal on earth 

 could perfift in for a fmgle hour, efpecially when 

 the rcfiftence arifmg from the denfity and tena- 

 city of the fluid is taken into confideration. This 

 fpecies of continued motion, on the contrary, 

 has an exad: correfpondence to the nature of the 

 organic particles, which, like artificial machines, 

 produce their elFeds by a continued operation, 

 and ftop immediately afterwards. 



In the numerous experiments made by Leeu- 

 wenhoek, he doubtlefs obferved Ipermatic animals 

 without tarls. He even mentions them in fome 

 places, and endeavours to explain the phaeno- 

 menon. For exampJe, fpeaking of the femen 

 of the cod, he fays *, ' Ubi vero ad ladlium ac- 



* cedcrcm obfcrvationem, in iis partibus quas a- 



* nimalcula cflb cenl'cbam, ncquc vitam neque 



P % * Cauda m 



* Tom 2. p. i^o. 



