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The observations of Seligmann and Shattock on the relation of spermatogenesis to the development of nuptial plumage in drakes probably receive their explanation from the above facts.
Even if it should be proved that in supposed cases of complete castration, such as that of Shattock and Seligmann, some testicular tissue remained at the site of the testes, it would still be true that the development of the comb and wattles is more affected by the removal of the sexual organs than that of the spurs or tail feathers.
Castration carried out when the drake was in nuptial plumage produced the same effect which was observed by Goodale, namely, delay, and imperfection in the assumption of the eclipse condition, but the observations of Seligmann and Shattock are more precise and detailed. One example described was castrated in full winter plumage in December 1906.
In such cases the secondary male characters may fee more or less completely developed. Thus Shattock and Seligmann state that ligature of the vas deferens made no difference to the male characters, and that after castration detached fragments were often left in different positions as grafts, when the secondary characters developed.
Thus a male foetus showing reptilian characters in sexual ducts was exhibited by Shattock at the Pathological Society of London, February 19, 1895. J. Kohlbrugge, "Die Umgestaltung des Uterus der Affen nach den Geburt," Zeitschrift für Morphologie, bd. iv, p. 1, 1901. The nerve endings in the genital region are the same as elsewhere.
There is complete disagreement between the results of Ancel and Bouin on the one hand, and those of Shattock and Seligmann on the other, with regard to the effects of ligature of the vasa deferentia. The latter authors, as mentioned above, found that after ligature not only the somatic characters but the testis itself developed normally.
Shattock and Seligmann, on the other hand, have placed in the College of Surgeons Museum the head of a Plymouth Rock which was castrated in 1901. It was hatched in the spring of that year. In December 1901 the comb and wattles were very small, the spurs fairly well developed, and the tail had a somewhat masculine appearance.
The question, however, to what degree the male characters of the cock are suppressed after complete castration is not so definitely answered in the literature of the subject. Shattock and Seligmann in their 1904 paper make no definite statement on the subject.
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