DISEASES OF POULTRY. 291 



M. Reaumur as a curiosity, he had white feathers mixed 

 with a good deal of ruddy color and brown, bordering 

 upon chestnut, his neck, back, wings, and belly, being 

 ruddy ; and even where there were white feathers, they 

 were mingled with ruddy ones. During the summer 

 vacation, at Paris, M. Reaumur was two months with- 

 out seeing the cock; but in this period, he became so 

 changed as not to be recognisable, his feathers having 

 become all over of the finest white. The following 

 year, he had partly white feathers, but the greater por- 

 tion was ruddy, or rather of a fair red. Here, then, was 

 a transition from white to a light-brown, indicating that 

 the whiteness of his feathers was not owing to the 

 number of his years. 



It has been remarked by several scientific observers, 

 that hen birds of various species, but more particularly 

 hen pheasants, put on, under certain circumstances, the 

 plumage of the male. Hunter, in his work on " Animal 

 Economy," is of opinion that " this change of character 

 takes place at an advanced age of the animal's life, and 

 does not grow up with it from the beginning." Mr. 

 Butler, another English physiologist, expresses a similar 

 opinion still more strongly, namely, that " all hen phea- 

 sants, as well as common fowls, would assume the 

 plumage of the cock, to a certain degree, if they were 

 kept to a certain age." Though this, however, to some 

 extent may be true, the reasons, or rather the accom- 

 panying circumstances and changes of constitution, 

 were first pointed out, it is believed, by Mr. Yarrell, 

 who seems to have determined that the change of color 

 depends on disease, or removal of the ovarium of the 

 fowl. Among seven hen pheasants, whose plumage 

 more or less resembled that of the male, he found the 

 organ in question diseased, with some variation as to 

 extent, and the progress of change observable in the 

 plumage bore a corresponding analogy. At the com- 

 mencement of this internal disease, the plumage does 

 not seem to be affected, for " hen pheasants in confine- 

 ment, and females of the common fowl in the poultry 

 yard, had been known to have ceased producing eggs 

 two years before any change was observed in their 



