106 



SUMMARY OF CURRENT RESEARCHES 



HELATING TO 



ZOOLOGY AND BOTANY 



(PEINCIPALLY INVEETEBRATA AND CRYPTOGAJIIA), 



MICROSCOPY Etc.* 



ZOOLOGY. 

 VERTEBHATA. 



a. Embvyolog-y. f 



Gonads in Relation to Secondary Sex-characters of Birds. | 

 H, D. Goodale has experimented with Roueii ducks, brown leghorns, 

 and cross-bred birds, observing the changes in plumage, etc., that follow 

 gonadectomy. 1. The plumage of the orchidotomized male is altered 

 comparatively little : some feathers grow somewhat longer, but other- 

 wise they are the same as in the unaltered male. In contrast, the 

 plumage-changes of the ovariotomized female are extensive, in respect 

 to shape, size, colour and colour-pattern. The plumage approximates 

 to that of the normal male. 2. As to head-furnishings, the capon's 

 comb and wattles remain of infantile type. In the castrated hens the 

 comb becomes very large and male-like in some, while in others it 

 remains comparatively small. As yet there is no clear evidence of the 

 causes of this difference. :?. All the capons reported on by Goodale 

 have well-developed spurs. In all the castrated hens in which the male 

 plumage also developed there were well-developed spurs, while in many 

 of those in which the assumption of male plumage was partial or tempo- 

 rary the spurs started to grow. Several times they continued to grow 

 after the plumage reverted, and though they did not grow quite as long 

 as those in which the removal of the ovary was complete, they were 

 otlierw'ise similar. Apparently, the dependence of the spurs upon the 

 internal secretion is relatively slight ; the inhibition exerted in the 

 female upon the development of the spurs is so slight that once develop- 



* The Society are not intended to be denoted by the editorial " we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, nor for auj^ claim to novelty or otherwise made by them. The object of 

 this part of the Journal is to present a summary of the papers as actually pub- 

 lished, and to describe and illustrate Instruments, Apparatus, etc., which are 

 either new or have not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so- 

 called, but also those dealing with Evolution, Development, Reproduction, and 

 allied subjects. 



Carnegie Inst. Washington, Publication No. 243 (1916) pp. 1-52 (7 pis.). 



