SEASONAL MODIFICATIONS IN TESTES OF VERTEBRATES 



2-59 



the interstitial cells little by little become 

 granular and increase both in number and 

 in volume. This increase continues until 

 January, when fat granules fill the cyto- 

 plasm of the interstitial cells. He traces 

 the fat from these cells into the tubules 

 during the following months. Mating 

 takes place in April and May, and at this 

 time the interstitial cells are at their 

 minimum. After mating the interstitial 

 cells rapidly increase. The tubules are 

 empty in June. Spermatogenesis proceeds 

 rapidly during the first part of July, and 

 with equal abruptness the interstitial 

 cells, deprived of their fat, return to 

 fibroblasts. Rana esculent a resembles Rana 

 fusca. The differences are matters of detail 

 only. 



interstitial cells increase after the mating 

 season when the tubules have been emptied 

 of sperm. Chart III from Champy's data 

 on Rana tem-poraria shows that interstitial 

 cell increase follows mating and accom- 

 panies ejection of spermatozoa from the 

 lobules. 



Friedman found that in the tree frog 

 (Hyla arborea) the tubules are full of 

 dividing cells throughout the month of 

 July and the intertubular space is then very 

 small. It contains only a few interstitial 

 cells here and there among the connective 

 tissue cells. In September, when sperma- 

 tozoa are formed, the interstitial tissue is 

 very rich and contains much fat. In 

 October most of the tubules contain only 

 spermatozoa, the quantity of intertubular 



JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT NOV. DEC. 





CHART IE RANATEMPORARIA. 

 ■ QUANTITY OF ^PEEfttTTC TISSUE, QUANTITYOF INTERSTITIAI. TISSUE 



In another paper (8) Champy presents 

 all data collected by himself together with 

 a very good review of the literature on 

 Amphibia. His charts show the quantity 

 of interstitial cells, but they do not give 

 an exact picture of the quantity of sperma- 

 togenic tissue. In Rana esculent a for 

 example, there is no spermatogenic tissue 

 present immediately before or during 

 mating. This is because Champy has 

 presented intensity of spermatogenic activ- 

 ity and not quantity of germinal tissue. 

 He states (8, p. Z5) that in Rana tem-poraria 

 the variation is still more marked than in 

 Rana esculenta because only one wave of 

 spermatogenesis takes place each year. 

 Here again the fact is made clear that the 



tissue is increased, and the interstitial 

 cells are full of fat. According to Champy 

 (8) Hyla arborea breeds in April, not in 

 September or October. Friedman was 

 apparently observing fall spermatogenesis, 

 common to Anura, and in some way 

 became confused regarding the mating 

 season. Friedman also reported that in 

 the toad (Bujo vulgaris) the interstitial 

 tissue reaches its greatest development 

 during spermatogenesis. These findings 

 were confirmed by Mazzetti (2.7) in a 

 general paper almost completely lacking 

 in data. But Champy's (8) careful study 

 shows that these authors apparently erred 

 in their reports. He states (p. -2.61) that 

 the testicular changes in Buf 



