186 ORGANISED FLUIDS. 



the corpuscles which it incloses seem to have a tendency to 

 escape from the kind of glutinous material which contains 

 them. This material, seeking, if we may express it thus, to 

 retain them, accompanies them to the situation only where 

 they find themselves to be arrested by a filamentous pro- 

 longation, which presents sufficiently well the appearance of 

 a tail, and even of a flexible tail, by reason of the lateral 

 movements which the little body makes in its progression. 

 There is merely in all this, as you see, a mechanical pre- 

 nomenon, and, in the movement which there takes place, but 

 a physical effect of the contact of two materials of different 

 densities ; contact which provokes these materials to mingle 

 together and to form but one, as arrives at the end of a time 

 more or less long. Abandon the semen to itself, taking care 

 that its watery part cannot evaporate by placing it in an 

 atmosphere saturated with humidity, at the end of a certain 

 time the mixture of the two materials will be complete, and 

 you will perceive no longer any thing but a homogeneous 

 fluid ; the pretended animalcules have disappeared. 



" If we wish to show you at the same time veritable 

 microscopic animalcules and the little gelatiniform masses 

 which move in the vehicle of the sperm, you will find a great 

 difference between the first and these last. I may fortify 

 my opinion on this subject with that of Buffon and Spal- 

 lanzani, who have denied that the masses of which I speak 

 were animalcules. 



" Amongst the persons who have admitted the existence of 

 these beings, there are those who have carried their preten- 

 sion so far as to class them in genera and species by taking 

 the form of the dilated extremity for the principal zoological 

 character. Somemicrographers, also, remarking the differences 

 in the corpuscles of the sperm, according as one procures this 

 liquid from the testicle, the vesiculas seminales, or after its 

 ejaculation, have pretended, from that circumstance, to de- 

 scribe a series of evolutions in the developement of these 

 so-called Cercariae. They have told us that these animals do 

 not exist in the product which occupies our attention at the 

 moment that it is formed ; that they appear but in the vesiculse 



