92 INFLUENCE OF HORMONES 



extract. This was the commencement of organo- 

 therapy. Since that time investigation of the more 

 important organs of internal secretion namely, 

 the gonads, thyroid, thymus, suprarenals, pituitary, 

 and pineal bodies has been carried on both by 

 clinical observation and experiment by a great 

 number of physiologists with very striking results, 

 and new hormones have been discovered in the walls 

 of the intestine and other organs. 



Here, however, we are more especially concerned 

 with the gonads and other reproductive organs. A 

 great deal of evidence has now been obtained that 

 the influence of the testes and ovaries on secondary 

 sexual characters is due to a hormone formed in the 

 gonads and passing in the blood in the course of 

 the circulation to the organs and tissues which consti- 

 tute those characters. The fact that transplanted 

 portions of testes in birds (cocks and drakes) are 

 sufficient to maintain the secondary characters in 

 the same condition as in normal individuals shows 

 that the nexus between the primary and somatic 

 organs is of a liquid chemical nature and not ana- 

 tomical, through the nervous system for example. 

 Many physiologists in recent years have maintained 

 that the testicular hormone is not derived from the 

 male germ-cells or spermatocytes, but from certain 

 cells between the spermatic tubuli which are known 

 as interstitial cells, or collectively as the interstitial 

 gland. 



The views of Ancel and Bouin, 1 published in 1903, 

 may be described in large part as theory. They 

 state that the interstitial cells appear in the male 

 embryo before the gametocytes present distinctive 



i C. R. Soc. de Biol., Iv, 



