Mr. H. J. Carter on the Spermatuloyij of a neic .species o/Nais. 101 



l-5600th of an inch) : a, with cell-wall ; b, without cell-wall ; c, 

 imaginary section of spherical form, more magnified, to show the 

 relative position of cell- wall, vesicles, and albuminous sphere ; if, 

 spherical form of ditto without cell-wall, showing the vesicles 

 still adhering to the albuminous s])here, also the nucleus. 



Fig. 6. Testes, so-called, magnified, containing bundles of spermatozoa (a) 

 and granules (e) : a', bundle more magnified ; b, single spermato- 

 zoon ; c, s])erm-cells from testes containing the characteristic 

 brown matter (on same scale as fig. 5) j d, globular masses of 

 granules bearing spermatozoa from ditto, of which the component 

 parts are proportionally magnified, each mass about 3-560Uths of 

 an inch in diameter (on same scale as fig. 5) ; e, loose granules. 



Fig. 7. Floating-cells, magnified (on same scale as fig. 5) : a, with cell- 

 wall ; b, without cell-wall ; c, after the bursting of the vesicles, 

 showing nucleus (fig. 5 c, d, are also equally characteristic of the 

 composition of this cell). 



Fig, 8. Portion of intestme magnified, to show the layer of hepatic cells 

 (the larger dark spots represent the bile-globules) : a, two hepatic 

 cells still more magnified. 



Fig. 9. Ovisac with spermatozoa and groups of ova in first stage of deve- 

 lopment : a, s])erm-cells (identical in appearance with floating- 

 cells), about 2-5(i00ths of an inch in diameter ; h, granular masses 

 sunounded respectively by s})ermatophorous vesicles (see a more 

 magnified view of one of these masses, isolated, fig. 14); c, two 

 groups of ova, each about 10-5()00ths of an inch in diameter, of 

 which the ova are about 2-5600ths of an inch in diameter each. 



Fig. 10. Ovisac with ditto ditto in second stage of development : a, sper- 

 matic cells unaltered, or with a little brown matter in their inte- 

 rior, as before. (From the constant ingress of floating-cells, even 

 to the end of the development of the spermatozoa, there are 

 always some of these in their primary stages present at the mouth 

 of the sac, and therefore some are frequently found here in all 

 stages of development ; but with each im|)regnation, the ovisac 

 appears to be cleared of everything except the remaining ova.) 

 b, granular masses surrounded by the spcrmatophorous vesicles, 

 now become conical (see fig. IG) ; c, single group of ova; d, single 

 ovum with germinal vesicle, more advanced in development than 

 the rest. 



Plate III. 



Fig. 1 1 . Ovisac with group of ova and spermatozoa in third stage of deve- 

 lopment : a, spermatic cells unaltered; A, granular masses sur- 

 rounded by vesicles now i)edicelled (see fig. 17) ; c, group of ova ; 

 d, ovum more advanced; e, another, less advanced; /, more mag- 

 nified view of germinal vesicle, showing nuclei or points in endo- 

 Slasm. 

 visac with spermatozoa fully developed : a, sperm-cells unal- 

 tered ; b, spermatozoa developed and se|)arate from the granular 

 masses (see fig. If); c, grouj) of ova; d, ovum just previous to 

 the disappearance of the germinal vesicle; e, effete granular 

 masses ; /, germinal vesicle more magnified, showing the nuclear 

 points surrounded by cells, and the nucleus or germinal spot 

 perishing or in progress of dissolution. 



Fig. 13. Sperm-cells from the ovisac (on same scale as fig. 5) : a, spherical 

 form ; 0, diffluent form ; c, undergoing fissiparation in the mother- 

 cell (the only instances of tiiis kind tliat I have observed have 

 Ann. &; Mag. N.' J lis/. Ser.3. Co/, ii. 8 



