EXPERIMENTS. 207 



therefore, it is unneceilary to fuppofe them en- 

 dowed with the natural inllintt: peculiar to flieep ; 

 Imce thofe of man, of the dog, and of the bitch, 

 move in the verv fime manner ; and fmce this 

 motion depends upon particular circumftances, 

 the principal of which is, that the fluid part of 

 the femen fliould be on one fide, and the thick 

 or filamentous part on the other ; for then the 

 whole moving bodies difengage themfelves from, 

 tlie filaments, and proceed, in the fame diredion, 

 into the more fluid part of the liquor. 



In another letter, written the fame year, and 

 addreiled to Boerhaave *, he relates fome farther 

 obfervations concerning the femen of the ram : 

 He tells us, that, when the hquor was put into 

 feparate glalles and examined, he obferved flocks 

 of animalcules moving all in the fame diredion, 

 and other flocks returning the contrary way. 

 He adds : * Neque illud in unica epididymum 

 ' parte, fed et in aliis quas precideram partibus, 

 ' obfervavi. Ad haec, in quadam paraftatarum 



* refedaportione complura vidi animalcula, quae 



* necdum in juftam magnitudinem adoleverant ; 

 « nam et corpufcula illis exiliora et caudae triplo 

 ' breviores erant quam adultis. Ad haec, caudas 

 ' non habebant delinentes in mucronem, quales 

 ' tamen adultis eife paffim comperio. Praeterea, 

 ' in quandam paraftatarum portionem incidi, a- 



* nimalculis, quantum difcernere potui, deftitu- 

 •tam, tantum il!i quacdam pcrexiguae inerant 



' particulae, 

 * See torn. 4. p. 304. 



