THE TESTICLE AND THE OVARY 333 



the vasa deferentia in Herdwick rams and in fowls, and these point 

 in the same direction. The animals operated upon acquired full 

 secondary characters. The authors suppose, therefore, that the 

 development of these characters is not brought about by metabolic 

 changes induced by a nervous reflex arising from the function of 

 sperm ejaculation. 



Foges ^ has described the effect of removing the testes of fowls 

 aiid 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, etc., being developed as in 

 uncastrated cocks. Foges concludes that the testes are organs of 

 internal 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, sometimes being 

 left in the normal position, and sometimes becoming dislocated and 

 ■ attached to the adjacent viscera or to the abdominal 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 " (but see p. 338). 



According to Loewy,^ the injection of testicular substance into 

 young capons causes the development of normal male skeletal 

 characters, as well as a better growth of the comb, etc. Further- 

 more, Walker * states that, in two experiments in which he injected 

 saline extract of cocks' testicles into two hens daily for several 

 months, the combs and wattles grew in size and became more 

 brightly coloured, reaching a maximum in five months. When the 



' Foges, " Zur Lehre der secundaren Geschlechtscharaktere,'' Pflilger's Arch., 

 vol. xciii., 1903. For an account of an earlier and less complete investigation 

 see Hanau, "Versuche Uber den Einfluss der Geschleohtsdriisen, etc.," Pflibger's 

 Arch., vol. Ixv., 1897. See also Sellheim {loc. cit.), who says that the weight of 

 the brain is slightly less in the capon (see above, p. 325). And see Cunningham, 

 loc. cit. 



2 Confirmed by Mackenzie and the author (unpublished experiments). 



' Loewy, " Neuere Untersuchungen zur Physiologie der Geschlechtsorgane,'' 

 Ergehnisse der Phys., vol. ii., 1903. 



* Walker (C. E.), "The Influence of the Testis upon the Secondary Sexual 

 Characters of Fowls," Proc. Roy. Soc. Med., vol. i., 1908. 



