EFFECTS OF CASTRATION OF HEN-FEATHERED CAMPINES. 245 



I 



might be due to different factors, or, as seems more probable, 

 due to the less complete dominance of the gene in the Campines 

 (in conjunction with the rest of the hereditary complex). Pos- 

 sibly different modifying genes are present that fortify the action 

 of the main gene in the Sebright. Further experiments will, I 

 hope, settle this question. 



The possible influence of other endocrine secretions must also 

 be examined, because in mammals there is some evidence that 

 other organs than the gonads may produce effects on the sec- 

 ondary sexual characters. Since the pituitary gland is one of the 

 internal glands that, par excellence, affects growth, I have ex- 

 amined its condition in the three Campines and compared the 

 organ with that in one normal hen-feathered bird of the same 

 race. In general there is little if any difference in size between 

 the pituitary in the normal and castrated birds ; but it appears to 

 be slightly larger in the castrates, more especially the part in- 

 closed in the sella turcica. Since I had only one normal bird for 

 comparison, this difference may be purely accidental ; but the ob- 

 servation justifies further search on more ample material. More- 

 over, accurate measurements of the gland will be necessary 

 before any value can be attached to such findings. 



It should be recorded, perhaps, that the kidneys in the smallest 

 and most completely castrated bird are reduced in size, but 

 whether this bird was abnormal in this respect can not be stated. 



I have not observed any change in the suprarenals in the cas- 

 trated birds. 



It is also interesting to note that the removal of the testes 

 of cock-feathered birds (to produce capons) causes in them also 

 some slight changes in the same secondary sexual characters 

 in which they differ from hen-feathered birds. The neck and 

 saddle feathers of the capon become longer, as do also the longer 

 wing coverts (Goodale, Morgan). It appears, then, that even 

 in the cock-feathered birds there is some inhibition to the growth 

 of these feathers produced by the normal testis. This inhibition 

 may be supposed to go so far in the hen-feathered races as to 

 completely stop down the male plumage to that of the hen. The 

 plumage of the hen, too, is known to be inhibited by the ovary ; 

 for, when the ovary is removed she develops the full cock- 



