INTERNAL SECRETION OF TESTICLE 171 



curve of development of the interstitial tissue are more or less 

 parallel. Similar results have been obtained lately by Ras- 

 mussen in the woodchuck. Rasmussen emphasized the dis- 

 crepancies between the older observations and his own, but 

 I think that no serious discrepancy exists. Rasmussen finds 

 that spermatogenesis attains its maximum about a month 

 sooner than the interstitial tissue, and further that the inter- 

 stitial tissue remains several months at its maximal state of 



Fig. 91. — Cyclic development of generative and interstitial tissue of 

 the testicle of hibernating mammals. Plain lines indicate 

 generative tissue ; dotted lines, interstitial tissue. Climax of 

 spermatogenesis during heat, hibernation from November 

 till ^Nlarch; birth of young indicated by x. — Parallel develop ■ 

 ment of generative and interstitial tissue in the hedgehog 

 and in Marmota marmota (for marm. marm. data available 

 only for some months). Some deviations between both 

 tissues in Marm. monax; no parallelism in the mole. — From 

 Rasmussen (with changes). 



development, whereas the curve of spermatogenesis is lowered 

 long before. But I think that it is impossible to draw from such 

 observations detailed conclusions in regard to time and quantity 

 of interstitial tissue or tubules, especially as all these con- 

 clusions are naturally derived from different individuals 

 which may show much variation. On the other hand all these 

 observations are a sufficient basis for the general conclusion 

 that in the woodchuck and in the hedgehog the interstitial 



