Hen-feathering in Male Fowl. 



277 



this time the control males were typically marked by long hackles, 

 saddle feathers and definite sickles. The thyroid-fed males re- 

 sembled females in each of these respects. In behavior, comb, 

 wattles and spurs, they were male, in feathering female. 



It was clear that the addition of thyroid to the diet of unaltered 

 males was somehow responsible for this condition. Turning to 

 the castrated birds that had been fed thyroid, it was equally 

 clear that the gonad was a necessary factor in the result. For 

 not a single castrated bird of either sex showed the least evidence 

 of thyroid feeding in any of the characters previously enumerated. 

 The thyroid-fed castrated females like their castrated controls, 

 approximated males in feathering. The thyroid-fed castrated 

 males exhibited the ultra male plumage characteristic of capons. 



The facts thus far considered relating to the secondary sex 

 characters are arranged for convenience in the accompanying 

 table. 







Comb and 





Plumage. 



Wattles. 





. Male 



Male 





.Male 



Female 



Normal and thyroid male . . . 



.FEMALE 



Male 



Normal and thyroid female. . 



. Female 



Female 





.Male 



Female 





. Male 



Female 



Castrated and thyroid male . 



.Male 



Female 



Castrated and thyroid femaleMale 



Female 



Males with hen-feathering induced by thyroid feeding are 

 indicated by capitals. All normal males thus fed were hen- 

 feathered without exception. In two instances, however, sickle 

 feathers began to appear among the tail coverts toward the end 

 of the thyroid-feeding period, suggesting a certain degree of escape 

 from the influence of the thyroid. This was possibly connected 

 with the fact that the birds were then getting less than the max- 

 imum dosage of thyroid compatible with their health. 



Search for the portion of the gonad through which thyroid 

 feeding achieved its effect led at once to the lutear cells originally 

 demonstrated by Boring and Pearl 1 in the ovary of the hen and 

 later in the testis of the hen-feathered Sebright, by Boring and Mor- 

 gan. 2 The latter stated their belief that the secretion of these cells 



1 Anat. Rec, 1917, xiii, 253. 



2 Jour. Gen. Physiol., 1919, i, 127. 



