DESCRIPTION OF PLATE 



Fig. 1. Four successive feathers; a, b, and c definitely, d almost certainly, from 

 the same follicle. These are from a golden Sebright ^vhich hatched Apr. 20 and 

 was castrated May 27. The first two are cocky, the second two henny in character. 



la. Immature feather plucked Sept. 3. 



16. Small section of the pinfeather which immediately replaced the above. 

 This was plucked Sept. 17. The section is taken from well out toward the tip 

 where barbules are lacking. The regions marked with crosses contain cells which 

 degenerate without forming barbules. The six barbs shown are broAvn, not black 

 as the photograph might suggest. 



ic. Section of the next pinfeather, which was plucked Oct. 2. The region is 

 comparable to that shown in b. Beginning Sept. 19 and continuing till Oct. 5, 

 about 0.5 mg. of testosterone propionate in oil was placed on the skin each day 

 in the region of the follicle or on the developing pinfeather. It will be seen that 

 under these conditions cells comparable to those marked with crosses in b de- 

 veloped barbules and were invaded by pigmentophores, black to the left, broAvn 

 to the right. 



id. Immature feather plucked Nov. 11 after the treatment had been resumed 

 Oct. 10 and repeated daily from Oct. 12 to 17. 



Fig. 2. Feathers from a golden Sebright which hatched Apr. 20 and was cas- 

 trated May 23. The upper row shows the effect of testosterone, the lower row 

 the comparable effect of theelin. A total of 5.6 rag. of testosterone propionate 

 in oil ^\as injected into the breast muscles during the period from Sept. 12 to 17. 

 The upper ro^v shows the tips of three feathers which ^vere in different stages of 

 development when the injections became effective. The one in the middle was 

 affected in its proximal part, the one to right throughout its whole extent. (Only 

 H — birds respond in this \vay; two hli birds of approximately the same size, age, 

 and history treated in the same manner sho^ved no detectable effects on their 

 plumage. All similarly treated specimens showed marked growth of comb and 

 change in attitude.) In the second row are shown tips of three more feathers 

 from the same bird plucked on Dec. 1 1 after 0.7 mg. of theelin in oil had been 

 administered during a period of one ^veek when these feathers ^vere in different 

 stages of development. 



Fig. 3. Feathers from a silver Sebright capon approximately one year old. On 

 Aug. 2, about 1.4 mg. of testosterone propionate Avas embedded in, or slightly 

 under, the skin near the center of a recently plucked area. The feathers shown 

 are from replacements plucked Sept. 9. They are arranged as nearly as possible 

 in the relative positions in which they grew and the api^roximate site of the 

 testosterone implant is indicated by a cross. The four central feathers show 

 varying degiees of "feminization"; the three peripheral ones and all the others 

 that grew in this region failed to show any effect from the treatment. 



[1663 



