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



been in the ovisac, never in the peritoneal cavity) ; d, agglome- 

 merated, presenting the "brown matter" (represented by the 

 dark shades) and isolated groups of vesicles in different parts ; 

 e, caudate form, also containing a little of the " brown matter ;" 

 f, single spherical sperm-cell presenting the "brown matter" in 

 its interior. 

 Fig. 14. Granular mass with vesicles, in the first stage of development, 

 4-5600ths of an inch in diameter (on same scale as fig. 5). This 

 is the smallest " granular mass " that I have met with, though 

 probabh' not the smallest that exists, as there must be some not 

 larger than the albuminous sphere of the floating-cell (see fig. 27). 



Fig. 15. Ditto, ditto, 15-5600ths of an inch in diameter (on the same scale). 

 These two figures show the relative difference in size of the 

 granular masses which compose the sperm portion of the contents 

 of the ovisac. 



Fig. 16. Granular mass (ll-5600ths of an inch in diameter) with vesicles in 

 second stage of development, i. e. when the latter become conical, 

 and the matter of the granular mass coarser : a, vesicles. 



Fig. 17. Granular mass (10-5600ths of an inch in diameter) with vesicles 

 in the third stage of development ; granular matter still coarser. 



Fig. 18. Granular mass (5-5600ths of an inch in diameter) with sperma- 

 tozoa still further developed, and attached in two groups. 



Fig. 19. Granular mass with spermatozoa fully developed and sei)arate, 

 though still retaining the vesicles at their ends (and probably 

 over their whole bodies, for it is so delicate that the spermatozoa 

 can hardly ever be said to be out of the vesicle until no appear- 

 ance of it is left). 



Fig. 20. Granular mass contracted after long exposure to water, showing 

 that sometimes there is a thin pellicular cell left in contact with 

 the developed spermatozoa, though it probably amounts to no- 

 thing more than a surface-condensation, and not a real cell. 



Fig. 21. Five figures showing the progressive formation of the spermato- 

 zoon, from the daughter-cell in the vesicle (according to Kcilliker) 

 to the common form under which the spermatozoon presents 

 itself both in the testes and ovisac : a, vesicle with daughter-cell, 

 according to Kolliker; b, spermatozoon with both extremities 

 extruded from the vesicle, which is kept distended in the centre 

 by the elasticity of its coils. 



Fig. 22. Granular mass (8-56()0ths of an inch in diameter) with sperma- 

 tozoa attached in four groups. 



Fig. 23. Granular mass with spermatozoa attached in one group. 



Fig. 24. Granular mass with sj)ermatozoa attached all over the mass, but, 

 by a current of water, all drawn in one direction, showing how 

 they may become "bundled" under these circumstances. 



Fig, 25. Granular mass covered with vesicles, through some of which the 

 caudal ends of the spermatozoa are projecting. 



Fig. 26. Granular mass (7-56()0ths of an incli in diameter) covered with 

 vesicles of the largest size, viz. 2'5-.560()ths of an inch in dia- 

 meter ; on the same scale as fig. 5. A few only of the vesicles 

 are figured here, for the purpose of showing that the material of 

 the granular mass is always extremely fine when surrounded by 

 the larger vesicles, a, vesicle more magnified ; b, after long ex- 

 posure to water, showing that when its refractive contents become 

 contracted, they assume a granular form, accomjjanied by a 

 nucleus. 



Fig. 47. Nais ulbida, natural size. 



