262 R. R. HUMPHREY 



of the next cycle are by that time sufficiently developed so that 

 interstitial cell 'intervention' is not required. What might occur 

 if all germ cells in the urodele were destroyed is, of course, prob- 

 lematic. In cases of extreme atrophy of the testis there is a more 

 or less complete disappearance of the interstitial cells (Cushing's 

 Case XXXII, p. 277, and Biedl, p. 396). 



The work of Steinach, who claims to have 'restored' old male 

 rats to youthful vigor and activity, is suggestive in this connec- 

 tion, as the stimulation was induced by causing testicular de- 

 generation. Steinach ligatured the testis of one side, leaving 

 the other intact. The ligatured testis of the 'restored' animal 

 was found to contain greatly developed interstitial cells, while 

 its geriTiinal tissue had atrophied. The period of persistence 

 of the ' restored' condition was not stated, the animals presumably 

 having been sacrificed before a return of senility. 



The association of the interstitial cells with degenerative 

 changes, in the urodele testis, is I think, clearly demonstrated, 

 both by my own observations and those of Champy. The 

 significance of such as association is another question. Though 

 the absence of typical interstitial cells from regions where sperma- 

 togenesis is going on precludes the possibility of their serving 

 the 'trophic' function sometimes ascribed to them, the stromal 

 cell, from which they develop, may serve some such purpose. 

 As these cells always surround the lobule in such a way as to be 

 between it and the blood vessels, the nutriment reaching the germ 

 cells must either pass through their cytoplasm or traverse inter- 

 cellular spaces adjacent to it. Conversely, if products formed 

 within the lobule are absorbed through blood or lymph channels, 

 such products must first pass through or between these stromal 

 cells. These might, therefore, be expected to react (as they do) 

 to changes in the metabolic condition of the lobule. 



What, then, is the source of the products (granules, lipoids) 

 seen when these stromal cells begin hypertrophy? Are they 

 derived from substances from within the lobule or are the mate- 

 rials forming them taken from the flow of nutriment passing from 

 blood vessel to lobule? To my mind, both sources seem possible 

 and probable. The hypertrophied cells doubtless receive end 



