2.58 



THE QUARTERLY REVIEW OF BIOLOGY 



cells. At the end of October and during 

 the winter months, when no spermato- 

 genesis is going on (only spermatogonia 

 are found), the interstitial cells disappear. 

 He does not indicate when mating 

 occurs, merely stating that spermatogene- 

 sis is going on during the summer and that 

 at the end of October only spermatogonia 

 are present. From this it might be in- 

 ferred that mating is in October when the 

 products of the summer and fall wave 

 disappear. From other sources of infor- 

 mation it seems that the mating period is 

 from the middle of March to the middle of 

 May. Friedman was apparently observ- 

 ing the early stages of a wave of spermato- 

 genesis whose products are kept until the 



spermatozoa are not present at this time, 

 but only reports that no spermatogenesis 

 is taking place. 



Chart II is based upon Friedman's 

 report of Rana fusca together with infor- 

 mation supplied by Mazzetti. It shows 

 very well that the increase in size of the 

 testis with spermatogenesis is accompan- 

 ied by interstitial cell decrease. It also 

 clearly indicates that the interstitial cell 

 increase follows mating and does not ! 

 precede it. 



In Rana viridis, now known as Rana 

 tsculenta, Friedman observed all stages of 

 spermatogenesis during late summer and 

 fall. From June to October most of the 

 tubules are small. After this spermato- 



APR. MAY JUNE JULY AUG. SEPT. OCT. 



CHART H RANAFUSCA. 

 -QUANTITY OPSPEKMATIC TISSUE, QUANTITY OF INTERSTITIAL TISSUE 



following spring, as is true for other 

 Amphibia. 



Nor does he record the size of the tubules 

 during spermatogenesis, though from his 

 discussion of the early spring and late fall 

 and winter conditions it appears that 

 from June to September the tubules are not 

 distended but round and the intertubular 

 space is large. 



Mazzetti (xf) confirmed Friedman's 

 report for Rana fusca. He stated that in 

 the fall, when all stages of spermato- 

 genesis are found, there is an abundance 

 of interstitial tissue. Toward the end of 

 October spermatogenesis ceases and the 

 interstitial cells diminish little by little 

 until they are no longer demonstrable. 

 He does not state, as does Friedman, that 



genesis takes place. During early August t 

 the interstitial cells are well developed. 

 In winter, when spermatogenesis continues j 

 and the tubules are distended, interstitial i 

 cells are no longer present. Mazzetti 

 also made observations on the testes of 

 this frog and reports that the interstitial 

 cells are abundant during the period of 

 intense spermatogenesis (time not given, 

 nor are his criteria for intense spermato- 

 genesis stated). His work is not thorough 

 and is confined to the fall season. 



Champy (7) observed that in Rana 

 esculenta during July the interstitial cells 

 undergo a regressive change and take on 

 the aspect of connective tissue cells. 

 Spermatogenesis is then most active. In 

 autumn, when spermatogenesis is arrested, 



