94 Mr. H.J. Carter on the Spermatology of a new species of Nais. 



ing, and that, as the vesicles under these circumstances could 

 not be projected from the granular mass on the caudal ends of 

 the spermatozoa as usual, the caudal ends had passed through 

 both their vesicles respectively and the mother-cell. Fig. 28 

 also represents another instance where the mother-cell of an 

 agglomerated mass appears to have remained. In some cases, 

 too, even where the mother-cell is not persistent, and the vesi- 

 cles, as usual, remain in contact with the granular mass, the 

 tails of the spermatozoa are thrust through their opposite side 

 (figs. 25 & 31-33), while not unfrequently both head and tail 

 may be projecting while the vesicle is in the centre, as before 

 mentioned (fig. 21 b). All this, however, is readily explained; 

 for the vesicle in which the spermatozoon is developed is so 

 flexible and plastic, that although the enclosed spermatozoon 

 can throw it into all kinds of shapes, and half extrude itself, it 

 is with the greatest difficulty only that it can throw it off alto- 

 gether, while it is frequently so delicate in structure, and so 

 diaphanous, that it is also very difficult to believe that it is not 

 a part of the spermatozoon itself, whence the spermatozoon 

 occasionally appears under a variety of shapes that are apt to 

 mislead the observer in his determination of its true form. 



Another point deserving of attention is the origin of the 

 " brown matter," not only in the sperm-cells of the ovisac, but 

 also in those of the so-called testes. This, as regards the former, 

 seems easily determined ; for if the sperm-cells of the ovisac be 

 derived from the floating-cells of the peritoneal cavity, and the 

 floating- cells subsequently become the hepatic cells, there is 

 every reason to infer that the brown colouring matter is but the 

 yellow colouring matter of the bile thus altered, — an inference 

 which derives confirmation from the fact that the globular masses 

 bearing spermatozoa in Ampullaria (figs. 35, 36) frequently bear 

 at the same time one or two large bright bile-globules (a), to- 

 gether with the granules characteristic of the hepatic cell, some 

 of which present the brown colour and character of the brown 

 granules of the sperm-cell, and appear, as before stated, to be 

 the abortive or effete remains of the bile-vesicles ; so that here 

 (figs. 35, 36) we have the granular mass with some of the vesi- 

 cles half-developed into spermatozoa; others united together, 

 forming bright amber-coloured bile-globules ; and a third set in 

 an abortive or effete state, presenting themselves under the form 

 of granules, some of which have the colour and appearance of 

 the brown granules of the sperm- cells. Thus we have not only 

 evidence of the sperm-cells producing bile, like the hepatic cells, 

 but also this fact corroborating the inference that both the sperm- 

 cells and hepatic cells are derived from the floating-cells of the 

 peritoneal cavity. 



