1 62 Gene H and Testosterone in the Fowl 



Synthetic testosterone propionate dissolved in sesame oil was injected in 

 0.5—1.0 mg. doses into the breast muscles of young bantam capons which had 

 already developed cocky plumage. In HH birds the usual effects were ob- 

 tained: a slight temporary drop in weight or retardation in growth, an almost 

 immediate increase in size and color of the comb, an increase in activity and 

 morale (which, however, is by no means entirely under humoral control), and 

 a more or less complete "feminization" of such potentially dimorphic feathers 

 as happened to be growing at the time of injection. Similar results with syn- 

 thetic testosterone have been obtained by Parkes and Selye,"* Champy,^" and 

 others. In this series there was some evidence, difficult to measure, that the 

 testosterone slightly accelerated growth, which perhaps helps to account for 

 a somewhat greater than usual length of some of the feminized feathers (pi. 1, 

 fig. 1, d). The similarity of this testosterone effect to that produced by theelin is 

 indicated in plate 1, figure 2, where there are shown partially and completely 

 "reversed" feathers resulting from both types of treatment. 



The foregoing experiments throw no additional light on whether the action 

 of the hormone is direct or indirect. This phase of the problem was next at- 

 tacked by the use of relatively minute quantities of testosterone which was 

 tested for its direct local action— a technique which has been used successfully 

 in studying the effects of estrone by Lyons and Sako''^ with mammals, and 

 Greenwood and Blyth^" with birds. For these purposes testosterone propionate 

 was employed as pure crystals, as an ingredient of a salve, and as an ointment 

 dissolved in sesame oil. 



The oil solution was applied directly to the skin, beginning soon after an 

 area on the back had been plucked. Usually about thirty feathers were re- 

 moved from each area to be tested, with others from one or more control areas 

 at a distance. Plate 1, figure 1, shows the effect of such treatment. Similar results 

 were obtained with both the silver and the golden Sebright. The chief objec- 

 tion to this method is that the oil tends to diffuse widely over the surface and 

 cannot easily be confined to a limited area. It is sufficiently selective, however, 

 to reveal that regenerating feathers in the treated area are more affected than 

 those at a greater distance. 



The salve proved more satisfactory for topical application than did the oil. 

 When applied over any appreciable area the observed effects were similar to 

 those following the application of the oil solution and generally involved 

 slight, but definite, effects on the comb as well as the feathers. Better results 

 were obtained from applying it in very small amounts to individual pin 

 feathers. The procedure was to find an area in which at least one pinfeather 

 was barely visible above the skin and then pluck all the surrounding feathers 

 and pinfeathers. The selected pinfeather was then painted with a tiny bit of 

 salve at regular intervals. A protocol will serve to illustrate the method and 

 results. 



Golden Sebright, hatched Apr. 20, castrated May 27. Aug. 9: weight 440 gm.; comb 35 (length 

 25 mm. + width 7 mm. + height 3 mm.), pale. An area about 25 mm. in diameter plucked clean 



