OVARIAN STRUCTURES OF VIVIPAROUS BLIND FISHES. 5 I 



ently influenced as to form and shape by the cell-body. The 

 entire surface of the stroma is covered by a layer of epithelium, 

 with a depth of 10 to I 5 ij.. The nuclei of these epithelial cells 

 appear quite distinct, are of a comparatively large size, and are 

 round or oval in shape. 



By far the largest amount of space in this epithelial layer is 

 given up to the numerous capillaries contained in it. They are so 

 numerous that, in cross-section, they appear as a row of large per- 

 forations, there being no more than a scant cell thickness between 

 them. The average diameter of these capillaries is less than 

 eight micra, in many instances being only five micra. This con- 

 dition is comparable to that described above for the ovisac and is 

 also unique (Fig. 8). 



The ovarian stroma of E, which contained the mature foetuses, 

 has been squeezed and crowded into a median position by the 

 young (Fig. 5). The cellular structure resembles that of the 

 ovary just described, except for such variations as would be 

 caused by its closely packed condition. The capillaries of the 

 epithelial layer, covering its surface, are not so numerous as in the 

 ovary of A, but are of larger size. The larger blood vessels are 

 more nearly cylindrical in form and have their walls more thick- 

 ened than have those in the first ovary. The lymph-spaces in 

 this ovary are compressed by the foetuses and temporarily elimi- 

 nated. 



Quite different in appearence from either of the two just de- 

 scribed, though somewhat intermediate between them in some 

 respects, and more advanced than the first in others, is the ovary 

 of D. In this the ovarian stroma has not so many nor such large 

 lymph-sinuses as A, but on the contrary has more nearly the ap- 

 pearance of that in E, from which it differs conspicuously, how- 

 ever, in not showing a "crowded" appearance, and in having quite 

 numerous ova of various sizes, though none of the latter are so 

 large as those of A, and in many cases are grouped together in 

 " nests " in a way largely unknown in A. The blood vessels are 

 comparatively numerous, large and quite thick walled. The 

 capillaries in the epithelial covering of the ovary so conspicu- 

 ous is that of A are so few in this case as to be visible only 

 when carefully searched for. The cellular structure near and 



