A MODIFICATION OF THE URODELE TESTIS. 1 5.^ 



with respect to the centrosomes. In none of the animals killed 

 in either November or March were maturation divisions to be 

 encountered. 



It would appear, therefore, that in Gyrinophilus a degeneration 

 of prim.iry -p rmatocytes takes place during the winter months. 

 Si i ne cell- of ihis stage of development are found in autumn only 

 in the ( audal part of the testis, it follows that only this region 

 will In- reduced in size through their later degeneration and 

 rption. 



In I-'.nryceti and in Plethodon cinerins the caudal append.^- i- 

 mm li le-- freijucntly encountered than in (!yrinof>liili(s or 



notion glutinosus. In these species, too, it i- tiv|ueiitl\ 

 MIL ill .1- to be overlooked, except in serial section- of the or^an, 

 and. in in. my cases, is so poorly marked off from the body of the 

 is th.ti it appears to be merely a caudal tapering of that 

 Structure. In its microscopic structure, and in its mode of 

 de\ elopiurnt it is, however, entirely comparable to tin- appenr 

 in the forms already considered. 



In l:;oyi'ea males a considerable proliferation - a cell- in 



the appendage often causes it to resemble a tesli- in miniature, 

 \\iili the same seriation of developmental stages HI- in the 



body of the te-tis ahead of it. Its germ cells are al\\a\ - retarded 

 in their development, however, as compared with those of the 

 it -MI- | n op t i. For example, in a well-defined appendage of thi- 

 -oi t, iii mid-August, the caudal lobules contain untransformed 

 -permatids, \\hile the corresponding caudal lobule- in the body 

 ol the testis .ire tilled with well-developed sperm. ito/o.i. l.arlicr, 

 in Jul\ , 1 have found an appendage filled with sperm. itorytes I, 

 the body of the testis at the same time containing trail-forming 

 -pcrinatids thn>ughout its caudal half. 



The modi- of origin of the appendage in Enrycca differ- only in 

 detail- from that described for other sprrie-. Tin- primary 

 -permatoiA tt-- do not normally develop until the spritiK month-. 

 A male killed in early May, for example, ha> the r, tudal third of 

 the testis tilled with the so-called syni/r-i- figure- characteristic 

 of the early part of their growth period. The de\elopnient of a 

 raudal .i|)|)endage through a winter or spring degeneration of 

 spermatid- (or -ro\\iug spermatocytes) is impoible in such an 

 animal. The caudal lobules of the u--ti- in sj)finvc show the 



