74 PETER OKKELBERG 



developed ovarian eggs there was, with one exception, no testicu- 

 lar portion. He concluded that in the young state nearly all 

 females were hermaphroditic and that the testicular portion of 

 the sex gland normally disappeared as the e'ggs became more 

 mature. He believed that fertilization was normally effected by 

 these hermaphrodites, since true males were so rare. Out of 

 hundreds of specimens examined he succeeded in identifying 

 only eight males. , 



Nansen ('87) also worked on Myxine, and came to the conclu- 

 sion that all the animals are males up to a length of 32 to 33 cm., 

 after which they change sex and become females. He regarded 

 this as a case of protandric hermaphroditism among vertebrates. 

 Dean ('97), as a result of his study of Bdellostoma stouti, doubted 

 the conclusion reached by Nansen, as also did Price ('96). It 

 was not, however, until 1904 that Schreiner proved by the exam- 

 ination of hundreds of specimens of Myxine that hermaphroditism 

 in this form is of a juvenile character and that each animal ma- 

 tures only one kind of germ cells. Schreiner divided the animals 

 examined into three groups, namely, males, females, and sterile. 

 In the males the testes occupy the posterior portion of the gonads, 

 while the anterior portion may not develop at all or may contain 

 ova arrested in their development and showing signs of degen- 

 eration. In the female the ovary occupies the anterior portion 

 of the gonad and is well developed, while the posterior or testicu- 

 lar portion is sterile and only slightly developed. The sterile 

 individuals were of two kinds : those that showed neither follicles 

 nor eggs and those in which both ova and follicles were found. 

 Ova were usually found in the testes of the males, ranging from 

 only one in some specimens to a large number in others. Out of 

 hundreds of specimens examined only nineteen males were found 

 without ova. The evidence obtained by Schreiner and later 

 confirmed by Cole ('05) shows that Myxine is not a protandric 

 hermaphrodite, but a juvenile hermaphrodite like the brook 

 lamprey. This same conclusion has been reached by Conel ('17) 

 for Bdellostoma as well as for Myxine. Conel believes that in 

 the males the sex gland may degenerate with age, and that this 

 accounts for the sterile individuals found bj^ Schreiner. 



