OVARIUM STRUCTURES OF VIVIPAROUS BLIND FISHES. 4/ 



D and E represent females of the same genus with a length of 

 83 and 65 mm. respectively. E was pregnant; the others were 

 non-pregnant. 



An examination of the ovisac and oviduct reveals quite a range 

 of variation, depending in the main upon the condition of preg- 

 nancy or upon the length of time that had elapsed since the close 

 of that period. 



In the ovary of D, which had not been pregnant at all, or at 

 least for so long a time that the ovarian structures had regained 

 their normal form, the wall of the oviduct and the ovisac is from 

 100 to 150 // in thickness at different places. Structurally, the 

 ovisac consists of at least four cell-layers. The outer, a sinuated, 

 peritoneal layer, immediatly beneath which there is a thicker layer 

 of longitudinal muscle fibers ; below this there is another some- 

 what thicker transverse band of muscle fibers ; on the inner sur- 

 face there is an epithelial layer containing numerous capillaries. 

 This will be described in detail below. The nuclei of the longi- 

 tudinal band are rod-like in appearance ; the nuclei of the second 

 muscle layer appear more nearly round, being evidently the cross- 

 sections of nuclei of the same form as those in the longitudinal 

 band. The innermost layer of epithelial cells has nuclei oval or 

 round in shape, while the peritoneal layer shows few nuclei, but 

 those which do appear are rod-shaped in section. Quite numer- 

 ous capillaries are found between the cells of these several layers 

 and in some places there are large blood vessels. 



In the ovary A from a female which had evidently given birth 

 to young but a short time previous to her capture, the ovisac 

 measures only 15 to 20 fi in thickness. Structurally it con- 

 sists of four or five thin cell-layers, between which there are 

 anastomosing capillaries. The outermost layer consists of peri- 

 toneum, the cells of which are very much elongated and com- 

 pressed. The muscle fibers beneath are mostly transverse and 

 of the non-striated type. The inner layer is epithelial and is 

 also much compressed. The nuclei of the muscle-fibers are long, 

 narrow, rod-like structures which stain deeply, as would be ex- 

 pected, with haematoxylin : the nuclei of the epithelium are oval 

 in form. The condition of this ovary does not permit me to go 

 into greater detail. 



