INTERSTITIAL CELLS OF URODELE TESTIS 221 



the course of the investigation, as well as those of Prof. S. H. 

 Gage, are gratefully acknowledged.^ 



Material and technique 



* 



The material upon which this investigation is chiefly based 

 consists of the testes of fifty-two specimens of Necturus macu- 

 losus, of which forty-nine animals were sexually mature. The 

 three immature animals were each of about 21 cm. body length; 

 the sexually mature animals ranged in length from 22 to 37 cm. 

 Twenty-five of these animals, including the three sexually imma- 

 ture specimens, were taken from Cayuga Lake; the remaining 

 twenty-seven were secured from Lake Erie at Venice, Ohio, and 

 shipped alive to Ithaca. These latter animals were larger than 

 the specimens taken locally, ranging from 30 to 37 cm. body 

 length, while the sexually mature specimens from Cayuga Lake 

 were from 22 to 30 cm. long. The Lake Erie animals seemed also 

 to be slightly in advance, seasonally, of the Cayuga Lake speci- 

 mens in point of changes in the interstitial cells — a difference 

 presumably due to a difference in temperature of the two en- 

 vironments. The animals were killed at intervals throughout 

 the year, specimens being sacrificed in every month save Feb- 

 ruary. The numbers of animals by months are as follows: 

 January one, March one, April ten, May eleven (two immature), 

 June seven, July six (one immature), August three, September 

 three, October four, November three, December three. 



Several methods of fixation and staining were employed. The 

 two fixers most extensively used were the dichromate-acetic- 

 osmic mixture of Bensley ('11) followed by his acid-fuchsin and 



* As this work was nearing completion, my attention was called to an article 

 by Champy ('13) who describes and figures interstitial cells in the testes of sev- 

 eral European species of urodeles. Champy is struck by the resemblance of the 

 interstitial tissue to the corpus luteum of the mammalian ovary, going so far as 

 to term it a 'veritable corps jaune testiculaire.' His results are largely in har- 

 mony with my own findings, although he is led to the statement of certain gen- 

 eral conclusions which are manifestly inapplicable to all urodeles. His results, 

 together with the brief comments of Friedmann and Ganfini, on the occurrence 

 of interstitial cells in Urodeles, will be considered in greater detail in the fol- 

 lowing pages of this article. 



