REPRODUCTIVE ELEMENTS IN MYXINE GLUTINOSA. 71 



more or less spherical capsules, varying very much in size. 

 By careful compression, the contents of these capsules can he 

 brought into view, but the structure is not very distinct. 

 When a capsule is burst by compression spherical cells are 

 seen to escape from it. These cells have a very delicate outline ; 

 they are very transparent, and the nucleus is only to be dis- 

 tinguished by careful focussing. These cells vary slightly in 

 size, the average diameter being 17 ju ; their appearance in the 

 fresh state is represented in fig. 14. '=f 



The interior of the capsules is completely filled up by 

 these cells, which in the fresh state are spherical while still 

 within the capsule, but become more or less polygonal after 

 hardening. The structure is brought out more distinctly by 

 preparing a piece of the tissue with hardening reagents, e.g. 

 corrosive sublimate or chromic acid, staining it, and then 

 mounting in a transparent medium. Fig. 7 shows the appear- 

 ance of such a preparation when magnified 50 diameters. The 

 capsules in the thickened border of the testis are seen to be 

 crowded with nuclei, but nothing further can be distinguished. 

 Under a higher power, if the preparation has been compressed, 

 the separate nucleated cells in the capsules can be distin- 

 guished. By cutting sections transverse to the thickened 

 border the structure is brought clearly into view. Fig. 8 

 shows the appearance of such a prepared and stained section 

 magnified 70 times. The outlines of the cells are not distinct, 

 but they can be followed under a higher power. I concluded 

 from the above facts that the cells in the capsules, after sub- 

 division, were converted directly into spermatozoa, which by 

 rupture of the capsules escaped into the body cavity of the 

 animal. There is every reason to believe that the fertilisation 

 in Myxine takes place outside the body. 



After identifying the male organ and investigating its 

 structure, I was surprised to find that in nearly all specimens 

 with very immature eggs the posterior portion of the sexual 

 organ had the same structure as the testis. This testicular 

 portion occupies about 2 inches of the posterior end of the 



