204 COMPARISON OF 



king them ; for he exprefsly tells us, that he aU 

 ways diluted the femen with water, to feparate 

 its parts, and to give more freedom of motion to 

 the animalcules * ; and yet, in his firft letter to 

 Lord Brouncker, he fays, that, when he mixed 

 the femen of dogs, in which he before had (een 

 innumerable animals, with water, they all in- 

 ftantly died. Thus Leeuwenhoek's firft experi- 

 ments were made, like mine, without any mix- 

 ture ; and it appears, that he was not in ufe to 

 mix the liquor with water till long after he be- 

 gan his experiments, and till he conceived the 

 idea that water killed the animalcules ; which, 

 however, is ^ot true : 1 imagine that the addi- 

 tion of water only diflblves the filaments too 

 fuddenly ; for, in all my experiments, I have 

 feen but very few filaments in the liquor, after 

 its being mixed with water. 



Leeuwenhoek was no fooner perfuaded that 

 the fpermatic animalcules were transformed in- 

 to men and other animals, than he imagined that 

 he faw two diftind: kinds in the femen of every 

 animal, the one male, and the other female. 

 Without this difference of fex in the fpermatic 

 animalcules, it was difiicult, he fays, to conceive 

 the pofTibility of producing males and females by 

 fimple transformation. He mentions thefe male 

 and female animalcules in his letter publifhed in 

 the philofophical Tranfadions, No. 145. and in 

 feveral other places f . But he attempts not to 



defcribe 



* Tom. 3. p. 92. 95. 



f See torn. i. p. 163. and tom. 3. p. loi. of his works. 



