230 REFLECTIONS ON 



* caudam dlgnofcere potui j cujus rei rationeni 

 ' elTe exiftimabam, quod quamdiu animalcula 

 ' natando loca fua perrecte mutare non poflunt, 

 ' tamdiu etiam cauda concinne circa corpus ma- 

 ' neat ordinata, quodque ideo fmgula animalcula 



* rotungum repraefentent corpufculum.' It would 

 have been more fimple, and more agreeable to 

 truth, to have faid, that the fpermatic animals of 

 this lifh fometimes have tails, and fometimes 

 have none, than to fuppofe that the tails wexQ 

 £0 exadly wound round their bodies as to give 

 them a fpherical figure. One would be apt to 

 think, that Leeuwenhoek had never fixed his 

 eyes upon, or defcribed any moving particles but 

 thofe which had tails ; he has given figures of 

 none that wanted tails, becaufe, though they mo- 

 ved, he did not regard them as animals. This is 

 the reafon why all Leeuwenhoek's figures of 

 fpermatic animals are very fimilar, and all drawn 

 with tails. When they appeared in any other 

 form, he thought they were imperfed:, or rather 

 that they were dead. Bcfides, it is apparent from 

 my experiments, that, inftead of unfolding their 

 taik, wherever they are placed in circumltances 

 proper for fwimming, as Leeuwenhoek infifts, 

 thefe pretended animals gradually lofe their tails, 

 in proportion to the rapidity of their motions, 

 till, at laft, thefe tails, which are bodies foreign 

 to the animalcules, or threads which they drag 

 after them, totally difappear. 



Leeuwenhoek, 



