72 Bashford Dean Ivlemorial Volume 



Nansen (1887) examined a "great many specimens'' of Myxine, caught near Bergen, 

 and observed that, "females only came under review, as I could not discover a single male 

 in spite of diligent search." He was of the opinion that Cunningham did not see the real 

 spermatozoa, but the abnormal product in this respect of an abnormal specimen. In 1886 

 Nansen (1887) visited Cunningham in Edinburgh, and examined the latter's specimens; 

 at that time he thought they resembled spermatozoa, but he saw only a few follicles which 

 had this appearance. Later, in his own specimens of Myxine, Nansen (1887) found sperma' 

 tozoa in the greatest abundance, and then did "not know what to say about those found 

 by Cunningham.'' Among several hundred specimens of Myxine examined by him, 

 Nansen recognized only very few males, and even these were unripe. In quite early 

 stages he found little difference between testes and ovaries. He generally found that large 

 specimens were females with well developed eggs; but in eels of about twenty-eight to 

 thirty-two centimeters in length the sexual organ anteriorly was but slightly prominent 

 and contained very many young ova, while the posterior portion was often very broad 

 and prominent, and had the appearance and structure of a testis. Upon teasing this 

 tissue in the fresh condition, Nansen found an abundance of spermatozoa in various stages 

 of development, and illustrated some of them in his Fig. 4. The spermatozoa were more 

 evident in the tissue after it was sectioned and stained. He concluded that, "those young 

 specimens (28-32 cm. in length) are, consequently, hermaphrodites, with quite immature 

 ovaries, but well developed testes: and they must be able to perform male functions." 



Nansen observed that in the large specimens of slime eels, which generally contained 

 a number of large and well developed ova, there were no reproductive elements, neither 

 ova nor testes, in the posterior portion of the generative organ, which here was very 

 narrow. Eels 'in size between that of the large females and that of the hermaphrodites 

 possessed sexual organs which were prominent in the anterior portion and contained 

 oblong young ova, whilst in the posterior portion they were of testicular nature and not 

 very prominent. These eels were, consequently, in a transition stage between the herma- 

 phrodite male and the female condition. "Indeed," wrote Nansen, "on examining a 

 sufficient number of specimens, we will easily be able to find every transition stage from 

 hermaphrodite males to fully developed females : and the rule seems to be that the larger 

 the specimen is, the more are the female organs developed, and the more do the male organs 

 disappear." He concludes then, "that Myxine is generally, or always (?), in its young 

 state, a male; whilst at a more advanced age it becomes transformed into a female. In- 

 deed, I have not yet found a single female that did not show traces of the early male 

 stage." Nansen found eels in which testicular follicles occurred along the free margin of 

 the whole reproductive organ (especially developed in the posterior portion, 6.7 cm. in 

 length); while in its anterior portion (7.4 cm. in length) young ova were present in the 

 mesorchium proximal to the testicular follicles, or mixed with the latter. He believed 

 that the few true males which he found were really transformed hermaphrodites, since he 

 could identify all the transitional stages between true males and hermaphrodites. Nansen 

 ends his discussion of hermaphroditism with these words : 



