THE SEMEX. 187 



seminales ; that in these they are as yet but simple globular 

 animals ; that in their progress they become developed by 

 the production of their caudal prolongations. Lastly, it has 

 been pretended, doubtless with the design of marking with 

 ridicule the opinions which we have reported, it has been 

 pretended, I say, that the spermatic infusorias became amongst 

 us, for example, veritable homuncules, having little anus, 

 little legs, &c. But this is sufficient in itself to put us on 

 our guard against an optical illusion which has unfortunately 

 seduced a great number of persons, from Leeuwenhoek, one 

 of its first favourers, even to MM. Prevost and Dumas, who 

 in these later days have still maintained the existence of the 

 spermatic animalcules." 



In the present day, it is needless to enter into any refutation 

 of the above views ; it cannot, however, fail to be observed 

 by the reader, that they are weakest just where they should 

 exhibit the most strength, that is, in the explanations given 

 as to the form and motions of the spermatozoa. 



Those physiologists who deny the animality of the sper- 

 matozoa would, of course, be very reluctant to admit of the 

 existence of any thing like organization in them ; while those, 

 on the other hand, who entertained a belief in their animal 

 nature would be most anxious to establish the fact of such 

 organization. 



The greatest possible difference of opinion then exists as to 

 whether the spermatozoa are organized or not, and if organized 

 as to the extent to which they are so. 



In the centre of the disc of the spermatozoa of man and some 

 other animals a light spot has been observed ; this some have 

 imagined to be a stomach ; others, again, have rejected this 

 idea, and thus account for its presence : the disc, they say, is not 

 of equal thickness, and, like the red blood corpuscle, is thinnest 

 in the centre, and which part, therefore, exhibits a lighter 

 tint than the remainder : this latter view is most probably 

 the correct one. The first opinion is entertained by Valentin, 

 and the second by Dujardin and Hcnle. Muller conceived 

 the spot in question to be a nucleus.* 



* Mullor's Physiology, p. 635. 

 Q 2 



