UROGENITAL SYSTEM OF MYXINOIDS 



131 



In the longer, i.e., the older, animals the testis band is wider 

 and thicker than in the younger males. 



The testis bands are folded more or less in the young males 

 and considerably in the older animals. In all, the bands have a 

 very granular appearance (fig. 85). The bands in the younger 

 males are hght gray in color, and yellowish in older animals. 



Transverse sections of the testis bands show that in minute 

 structure they are very similar to those of Myxine. Single germ 

 cells and follicles of all sizes, from very small to large, are pres- 

 ent. In a single section all stages of mitotic figures may occur, 

 and many of the follicles contain spermatozoa (fig. 79). Each 

 follicle has for its wall a single row of stroma cells, arranged end 

 to end, and outside this are two or more concentric layers of 

 fibrous connective tissue. Capillaries occur here and there in 

 the connective tissue and stroma between the follicles. The 

 primitive germ cells are limited to the distal end of the band, 

 and here the follicles are smaller, their walls are not so promi- 

 nent and there is less connective tissue than in the proximal 

 part, where the large follicles are located. The entire band is 

 covered by a single layer of squamous epithelium which is a 

 continuation of that of the mesorchium. In no place is there 

 columnar epithelium around the testis band as is described for 

 Myxine. 



Cunningham ('87) and Nansen ('87) have advanced the theory 

 that Myxine is a protandric hermaphrodite, functioning as a 

 male when young (28 to 32 cm. long) and as a female when older 



