ORGANS OF INTERNAL SECRETION 311 



Shattock and Seligmann l also have performed experiments 

 on the results of occluding the vasa deferentia in Herdwick 

 rams and in fowls. The animals operated upon acquired full 

 secondary characters. The authors suppose, therefore, that the 

 development of these characters is not brought about by rue tn- ~ 

 bolic changes induced by a nervous reflex arising from the 

 function of sperm ejaculation. 



Foges 2 has described the effect of removing the testes of 

 fowls and transplanting them to abnormal positions in the 

 body cavity. In the successful experiments it was found that 

 the presence of functional transplanted testes exercised the 

 same influence over the development of the secondary sexual 

 characters as testes growing in the normal position, and that 

 the appearance of " capon " characters was averted, the 

 comb, wattle, spurs, &c., being developed as in uncastrated 

 cocks. Foges concludes that the testes are organs of in- 

 ternal secretion, and control the development of the male 

 characters. 



Shattock and Seligmann have also described the effects of 

 testicular transplantation and incomplete caponisation in fowls. 

 In certain cases the testes are stated to have broken up during 

 the operation, so that minute fragments were retained, some- 

 times being left in the normal position, and sometimes becoming 

 dislocated and attached to the adjacent viscera or to the ab- 

 dominal wall. Although these pieces of testicular substance 

 continued to produce spermatozoa, they were virtually ductless 

 glands. In such cases the secondary sexual characters of the 

 cock developed to a varying extent which seemed to depend 

 upon the amount of testicular substance left behind. " One 

 must regard the external character of maleness as a quantity 

 which varies proportionately with the amount of gland tissue 

 present." 



1 Shattock and Seligmann, " Observations upon the Acquirement of 

 Secondary Sexual Characters, indicating the Formation of an Internal Secre- 

 tion by the Testicle," Proc. Roy. Soc., vol. Ixxiii., 1901. The same investi- 

 gators also attempted to obtain further evidence by grafting together two 

 cocks, one castrated and the other normal, but these experiments were 

 unfortunately a failure, one of the birds always dying after a short time, 

 Trans. Path. Soc., vol. xlvi., 1905. 



2 Foges, "Zur Lehre der secundaren Geschlechtscharaktere," Pfluger's 

 Archiv, vol. xciii., 1903. 



