and t'ertilization tn the N ematoidea. iy7 



Upon this point wc can give no opinion. We have certainly 

 seen nucleated cells furnished with very short processes which 

 were still capable of motion, but we have never succeeded in 

 detecting the extension of processes by nucleated cells which 

 were not previously furnished with a single process. 



Sometimes, moreover, females occur in which the last forma 

 of the cycle of development of the zoospermia are wanting. 

 These are undoubtedly such as have only been very recently 

 impregnated. 



\Vc have made exactly similar observations in an Ascaris 

 from the intestine of Bufo cinereus, which is nearly allied to 

 Ascaris acuminata, and perhaps identical with Ascaris commu- 

 tata, Diesing. 



We have also confirmed Schneider's observations on Cucul- 

 lanus eleyans, although, in this case, from the small size of the 

 seminal corpuscles, it is more difficult to convince oneself of 

 the extension and retraction of the processes. 



Lastly, we shall add, that, according to oral communications, 

 Wagener and Lieberkiihu have completely confirmed Schneider's 

 discover}', in the animal mentioned by the latter in his memoir 

 under the name oi Angiostuma Limacis, Duj. But they assert 

 that the worm in question is no Anyiostoma, but an undescribed 

 Nematoid worm. 



There can consequently be no doubt about Schneider's dis- 

 covery of the power of motion of the seminal corpuscles in the 

 Nematoidea. The only question is, whether this faculty belongs to 

 the seminal corpuscles of all the Nematoidea. In reference to this, 

 we have in vain examined those of Ascaris siiilla and-^. mijstax. 

 In these we have been unable to detect any signs of movement. 

 Nevertheless we can by no means deny that these seminal cor- 

 puscles possess some power of movement. Their llocculent ex- 

 tremity too closely resembles the lobed base of the seminal 

 corpuscles of Strongylus auricularis for us to suppose that it is 

 not an organ of motion. Perhaps in these zoospermia the 

 movements are so slow that they have escaped us. Perhaps, 

 also, we may not have hit the right degree of concentration of 

 the sohition of salt. 



6. Retrospect. 



In conclusion, we will sum up the principal results of this 

 memoir : — 



1. Bisclioflf's epithelial conules are seminal corpuscles, as 

 Nelson, Meissner and Thompson have correctly asserted. 



2. Meissner's female germ-cells have no existence. The re- 

 presentation given by this observer of the formation of the egg 

 in the Nematoidea, must be regarded as entirely wrong. 



