1903.] The Acquirement of Secondary Sexual Characters. 49 



" Observations upon the Acquirement of Secondary Sexual 

 Characters, indicating the Formation of an Internal Secretion 

 by the Testicle."* By S. G. Shattock and C. G-. Seligmann. 

 Communicated by Professor J. K. Bradford, F.B.S. Eeceived 

 December 14, 1903— Bead January 28, 1904. 



The Problem Stated. 



The question taken up in the present communication may be 

 concisely stated as follows : — 



The most prominent and obvious function of the testicle is the 

 formation of the sperm. Under normal circumstances this is dis- 

 charged ; it constitutes, that is to say, an external secretion. 



In spermatogenesis the male attributes culminate. There is, how- 

 ever, another element in maleness, of a different kind, less essential, 

 yet in many cases well pronounced, viz., the acquirement of certain 

 external characters which distinguish the male from the female in 

 many groups of living forms. 



That the development of such secondary characters is related jto 

 some function of the testicle, appears from the results which follow 

 castration when carried out before the advent of sexual maturity. On 

 what, then, does the production of these characters depend ? 



It is conceivable that the result may be due to a nervous reflex 

 arising out of the physical function of the sexual mechanism. This 

 view our observations seem to us to disprove. 



The- genesis of the external male characters must, in our opinion, be 

 transferred from the influence of the nervous system to the realm of 

 chemistry. It depends, with more probability, upon the formation 

 of a second secretion by the testicle, the absorption of which into the 

 circulation induces the metabolic changes that reveal themselves as 

 secondary sexual characters. 



The suggestion that such an internal secretion might be elaborated 

 by the " interstitial cells," which lie in groups between the tubuli, 

 was put forward by one of us (S. G. S.)f in 1897. 



The experiments to be recorded were, in fact, primarily designed 

 with the object of eliminating any part that might be plaj^ed by the 

 tubuli in this connection, and so of determining whether any function 

 could be ascribed to the cells named. 



They consisted in ligation of the vasa cleferentia in the young of 

 certain forms in which the male exhibits marked secondary characters. 



* Towards tlie expenses of this research, a grant was made by the Council 

 of the Royal College of Surgeons ; and by the British Medical Association, on the 

 recommendation of the Scientific Grants Committee of the Association. 



f ' British Medical Journal,' Feb. 20, 1S97. 



VOL. LXXIIL E 



