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 curious 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 1858, 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- 
