Vol. XXIII. August, 1912. No. j 



BIOLOGICAL BULLETIN 



THE INTERSTITIAL CELLS AND THE SUPPOSED 

 INTERNAL SECRETION OF THE CHICKEN TESTIS. 1 



ALICE M. BORING. 



The problem presented in this paper was suggested to me by 

 Dr. Pearl in connection with some work of his on the time when 

 the secondary sexual characters first appear in the domestic 

 chicken. The domestic chicken has a long list of secondary 

 sexual characters. Will the cytology of the reproductive organs 

 throw any light on the cause of the development of these secon- 

 dary characters? The observations described in this paper deal 

 with the cytology of the testis, with especial reference to the 

 problem of secondary sexual characters. 



The problem of the cause of the secondary sexual characters 

 has been approached in many ways, but the favorite one is the 

 internal secretion theory, that is, that the secondary sexual 

 characters are dependent on a secretion formed by the cells of 

 the primary reproductive organs. Some phases of this theory 

 consider the germ cells themselves as the source of this secretion, 

 but oftener the so-called interstitial cells are regarded as the 

 secreting agents. We find frequent references to these inter- 

 stitial cells in the literature, but there has been great confusion 

 between the terms "interstitial tissue" which might be any 

 connective tissue lying between the seminal tubules, and the 

 term "interstitial cells," which by some workers is used for gland 

 cells among the connective tissue between the tubules. Workers 

 disagree as to whether these gland cells are epithelial or mesen- 

 chymous in origin. Another term frequently used is "interstitial 

 gland" which seems to be used for any large accumulation of the 



1 Papers from the Biological Laboratory of the Maine Experiment Station, 



No. 38. 



141 



