108 The Spermatogenesis of Desmognathus Fusca 



developing, these enlargements being connected by more constricted 

 portions. The enlarged parts are identical in structure, each with a 

 succession of stages, from the primary spermatogonia at one end to the 

 degenerated lobules at the other. Their occurrence evidently means 

 that there have been 2, 3 or 4 centers of growth, either primary — in 

 the original cord of germ cells; or secondary — by the division of residual 

 spermatogonia left when the lobule, as such, disappeared. There seems 

 to be no absolute correlation of this condition with other structural 

 features of the salamander, save that the presence of two or more 

 enlargements occurs more often, in fact, quite constantly, in large ani- 

 mals. A similar division of the testis into "lobes" occurs in other 

 salamanders with an elongated body, and has been noted in Amphiuma 

 and Spelerpes. The segmented condition of the organ in Coecilians is 

 perhaps to be associated likewise with the elongated form of body. In 

 the European salamander, Meves, 96, and others have noted a division 

 of the testis into lobes, whose size, shape, and possibly existence, are 

 dependent upon the stage of development of the spermatozoa. Of these 

 lobes, 4-5 in number, the more caudal contain ripe spermatozoa, the 

 cephalic lobe, the cells that will form the spermatozoa, and they are so 

 arranged that different stages follow one another in cephalo-caudal 

 succession. In the cephalic tip, which is prolonged into a thread, the 

 spermatogonia are located, caudad of which are the spermatocytes in 

 successive stages of maturity or division. The lobes also possess differ- 

 ent color according to the contents, the spermatozoa imparting a yellow- 

 white, the cells, a transparent blue-gray. With these lobes, which are 

 not well marked in Desmognatlius, must not be confounded the succes- 

 sion of enlargements spoken of above, which are in effect independent 

 testes. 



In the spermatogenetic cycle of Desmognathus degenerations seem 

 to occur quite constantly and normally. These are: (a) a degener- 

 ation of spermatozoa left over from the preceding year. This occurs 

 in the organ in the spring, and even, it would appear, in the winter 

 and preceding fall; (b) likewise spermatids undergo degeneration in 

 the spring; (c) when the spermatogonia cease to undergo transforma- 

 tion into spermatocytes in the summer, the last cysts of spermatogonia 

 apparently undergo a chromatolysis and solution, and the boundary 

 between the spermatocytes which are to form spermatozoa that season 

 and the spermatogonia remaining over until the next summer, is thus 

 well marked. After the expulsion of the spermatozoa and the collapse 

 of the lobule, the follicle cells degenerate and disappear. These degen- 

 erations, together with the divisions and structure of the spermatogonia 



