394 INTERNAL SECRETIONS 



Pease (1922), who examined 28 testicles of normal and hen- 

 feathered cocks of different ages and at different seasons. 

 Pease stated that the luteal cells are to be found in the testicle 

 only in young birds before sexual maturity, but both in hen- 

 feathered and in normal cocks. These cells disappear when 

 spermatogenesis begins, and they are absent when the bird 

 becomes older. Pease inclines to the view that the luteal 

 cells have a nutritive function, and he thinks that the contrary 

 conclusion of Morgan was due to an insufficient number of 

 hen-feathered birds having been examined. Nonidez (1922), 

 a pupil of Morgan, has re-examined the question of the 

 luteal cells in birds, and stated that they are derived from 

 young seminiferous tubules, the cellular elements of which 

 undergo fatty infiltration. Since similar cells in the ovary 

 arise from the degenerating sexual cords, "there can be little 

 doubt about the homology of the cells in both organs." The 

 process takes place in late embryos and young chicks, and not 

 only in the Sebright race, but also in other breeds, as, for 

 instance, in the Rhode Island Reds and in the Leghorn. 



Lately Yocuni (1923, quoted from Morgan, 1923) and Morgan 

 (1923) stated that luteal cells are absent in the testis of the 

 phalarope, whereas these cells are to be found in the ovary. 

 In this species the female is more highly coloured than the male. 

 Morgan concludes, therefore, that the failure of the male 

 phalarope to develop a highly coloured plumage cannot be 

 ascribed to luteal cells. 



Castration experiments of ]\Iarshal] (see Punnett and Bailey, 

 1921) on henny-feathered Sebright cocks may also be mentioned 

 here. Three out of six unilaterally castrated animals developed 

 some feathers of the cocklike intermediate type, and these were 

 almost entirely confined to that side of the body on which the 

 testicle was removed. Two of three birds later on became 

 fully henny on both sides (the third was killed previously). 



(h) Experimental. 



An interesting statement was made by Goodale (19 16 a) about 

 castrated Brown Leghorn hens. He found that certain cas- 

 trated hens having acquired, as is the rule, the male plumage, 

 may some time afterwards change the plumage again towards 

 the female type. The plumage may then be changed a second 

 time to a male one. Such an observation Goodale made on 



