24 DR. HAMILTON ON THE PLUMAGE OF THE PHEASANT. [Feb. 11, 



character of every animal is that which is marked by the properties 

 common to both sexes, which are found in a natural hermaphrodite, 

 as in the snail, or in animals of neither sex, as the castrated male or 

 spayed female. They are carious facts in the natural history of 

 animals, that by depriving either sex of the true parts of generation 

 they shall seem to approach each other in appearances." 



In some species of animals, that have the secondary properties we 

 have mentioned, there is a deviation from the general rules by the per- 

 fect female, with respect to the parts of generation, assuming more or 

 less the secondary character of the male. John Hunter, like Butter, 

 considers that this does not arise from any action produced at the 

 first formation of the animal, nor grows up with it, but seems one 

 of those changes which happen at particular periods. He goes on 

 to describe some hen-pheasants having the plumage in part of the 

 male, and says, " I found the parts of generation to be truly female, 

 they being as perfect as any hen-pheasant that is not in the least 

 prepared for laying eggs, and having both the ovary and oviduct." 

 He says, " From what has been related of these birds we may con- 

 clude that this change is one of the effects of age, and obtains to a 

 certain degree in every class of animals. We find something similar 

 taking place even in the human species ; for that increase of hair 

 observable on the faces of many women advanced in life is an ap- 

 proach towards the beard, which is one of the most distinguishing 

 properties of man. Thus we see sexes, which at an early period had 

 little to distinguish them from each other, acquiring about the time 

 of puberty secondary properties which clearly characterize the male 

 and female, — the male at this time receding from the female, and 

 assuming the secondary properties of the sex. The female at a much 

 later time of life, when the powers of propagation cease, loses many 

 of her peculiar properties, and may be said, except from mere struc- 

 ture of parts, to be of no sex, even receding from the original cha- 

 racter of the animal, and approaching in appearance towards the 

 male." 



In the years 18.58, 1859, and 1860 this peculiar alteration of 

 structure in the female organs of generation in the Pheasants was 

 particularly prevalent in some parts of England. I had the oppor- 

 tunity of examining many specimens, and was able completely to 

 confirm Mr. Yarrell's views on this subject. Indeed, the majority 

 of the birds were young females, many of them being birds of the 

 year, some being in their first moult. I found also that the plumage 

 varied and approached that of the male, not in accordance with the 

 age of the bird, but with the amount of disease of the generative 

 organs. The greater the destruction of the ovarium and oviduct, 

 the nearer the plumage assimilated that of the male. 



For example, in birds with the hen-plumage predominating, the 

 ovarium and oviduct exist as in the fecundating hen, the small ova 

 lying in considerable numbers in the ovarium, the ovarium and ovi- 

 duct showing dark lead-coloured masses of disease. 



In birds with the plumage of the male in a measure exceeding that 

 of the female, the ovarium is considerably diminished in size, dark- 



