86 INFLUENCE OF HORMONES 



good deal of gloss. After this the nuptial plumage 

 developed again, and on November 12 the bird 

 was in full nuptial plumage, with good curl feathers 

 in the tail. The only trace of the eclipse was the 

 presence of a few brown feathers on the flanks. This 

 bird was killed July 30, 1908, when the bird was in 

 eclipse, but not perfectly so, as there were vermi- 

 culated feathers mixed with eclipse feathers on the 

 breast, abdomen, and flanks. Dissection showed on 

 the right side a series of loosely attached nodular 

 grafts of testicular tissue, in total volume about 

 the size of a haricot bean: on the left side two 

 small nodules, together about the size of a joea, 

 and two other grafts at the root of the liver and on 

 the mesentery. Several other cases are described, 

 and the general result was that the eclipse was 

 delayed and never quite complete, while although 

 the nuptial plumage was almost fully developed in 

 the following winter, it retained some eclipse feathers, 

 and was also delayed and developed slowly. 



Several drakes were castrated in July when in the 

 eclipse condition, and although the authors state, in 

 their general conclusions, that this does not produce 

 any constant appreciable effect upon the next 

 passage of the bird into winter plumage, they 

 describe one bird so treated which on November 18 

 retained many eclipse feathers : the general appear- 

 ance of the chestnut area of the breast was eclipse. 



It must be remembered that not onlv was the 

 castration in these cases incomplete, but also that 

 it was performed on mature birds. Birds differ 

 from Mammals, firstly, in the difficulty of carrying 

 out complete castration, and secondly, in the fact 

 that the occurrence of puberty is not so definite, and 



