302 ANIMAL PARASITES. 



application of water or acetic acid, occupies two thirds of the 

 entire cell, and possesses a small, dark, nucleolus. These struc- 

 tures are exactly like those which are met with in the vagina of 

 fecundated females ; but the corpuscles found in the vagina are 

 somewhat clearer in their outer part, and have a distinct hemi- 

 spherical nucleus or body in their interior. Both with and with- 

 out the use of reagents we find that the similar structures taken 

 out of the vas deferens, and out of the lowest parts of the vagina 

 and uterus of newly impregnated females, exhibit exactly the same 

 conditions of form and structure. Their size, their general 

 appearance, their molecular external layer, and the peculiarly 

 curved form of the nucleus or inner portion, with a granular mass 

 around the nucleolus on the open side, agree so much, that 

 we cannot avoid admitting that the structures in question, occur- 

 ring in the female generative organs, have been transferred there 

 from the male organs, and are therefore seminal elements, which 

 only arrive at their higher development in the female organs. 

 We may say, therefore, that the male nematode worms deposit 

 their semen in an immature or half-mature state. 



The changes undergone by these structures in the female 

 organs are, according to Meissner, the following : The nucleus 

 attached to the wall of the development-cell becomes clearer, and 

 loses its radiate structure. At the periphery of the nucleus is 

 formed a sharp, refractive line, or a dark seam, the substance of 

 a portion of the nucleus, and indeed that adhering to the 

 cell-wall, becomes condensed, whilst the portion lying towards 

 the interior of the lumen of the cell, remains unaltered and finely 

 granular. Whether in certain other Nematoida, as in Mermis, 

 the entire nucleus is condensed, so as to become converted into a 

 bacillar corpuscle, is still unknown. In the Ascarides, the last- 

 named structure acquires the appearance of a flat, watch-glass or 

 saucer-like corpuscle, which gradually encloses the portion still 

 remaining granular, and endeavours to push its extremities 

 together from the periphery, but without ever entirely closing. 

 At the same time it thickens somewhat, so that we see double 

 outlines, and it has acquired the form of a bell-shaped beaker, 

 open at one end, and somewhat turned outwards at the edge, 

 with finely granular contents. The process either closes with 

 this, and the seminal corpuscle becomes free, or the beaker 

 extends still more and becomes thinner, like a small test-glass; 

 the closed end uiwally thickens in a clavate form, and then bends 



