A MODIFICATION OF THE URODELE TESTIS. 163 



6. The development of spermatogonia for the next spermato- 

 genetic cycle- occurs at the normal time in the appendage, 

 increasing it- -ize to that of the "body" of the te-ti-; this 

 explain- the annual disappearance of the appendage in -pc 

 posse ing it. 



7. The de\ eli.|)inent of an appendage of the type here described 

 i- po--ible only in certain Urodeles with a te-ti> of -implc t\ pe and 

 marked polarity. It is of almost constant occurrence in (.iyrino- 

 f)liilns and rictlnxlon glutinosns. 1 



Post <>''''. Since the foregoing paperwa- placed in the hand> 

 of i lie edii<>r, a number of Urodele males captured in the -pi ing 

 and -ummcr of i ( J4 have been examined. Thc-e animal-, par- 

 ticularly- in the case of one species, show a \er\ -inking dilh r- 

 ein Irian tho- t - of the four preceding years. While annum 

 t\\eiity-i\\o a<lnlt Plelhodon glutinosus males captureil betv. 

 January and September in 1920, '21, '22, and nlv one lack- 



the i harai ten-tie appendage above described, not one ot the 

 nine i.iken in 1^24 jiossesses this structure. In tho-e m.de> 

 captnri-d e.ulie-t in the season (May and early June. i'ijj . 

 normal -permatocytes still occupy that camlal portion (1 | the 

 is in \\hich sj>ermatids are commonly found to h.i\e been 

 I'oimed ineaiK autumn. Evidently few or no maturation divi- 

 sions o,,innd in the fall of 1923, and as a rc-nlt. leu or no 

 -pei in .iiids \\ere present to degenerate during the u inter ol 

 ). Ab-i-nce of the appendage in \n^\ i- the natural 

 it -nit ol -uch retarded spermatogenesis. 



The failure of the maturation divisions to begin in the fall of 

 KU3 i- undoubtedly a consequence of climatic condition- ob- 

 taining during the spring and possibly also the fall of that year. 

 \\ . it her bureau records at Ithaca show that the avei mpera- 



ture for Ma\, IMJ.^. was 4.8 degrees below that of the normal 

 (av< t .v \<ars). Plethodon males taken in July, n>^\. 



>h>u ^p'i-mato-i-nesis retarded by from tuo to four \\eek- as 

 comp.ire<l \\ith males taken in other years, a retardation 

 pre-umably due to the lowered temperature above noted. This 

 retardation apparent in July would undoubtedK dcla\ com])le- 



1 Tin- \\ritn \\ i-ln-< ti> ai-ki. the helpful sugK .nnl critii i-m of Dr. 



I: 1 Kiiii;-;t'iiry ..i ("onu-H t "nivi-rsity. in whose laboratory tin- inv.^tiK.ition was 

 in. 



