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Mr. Yarrell on the 
from the circumstance that in some of the preparations of the 
parts of the hen-pheasants examined, the distinct globular 
forms of numerous ova are still apparent, but altered in 
colour ; from which it would appear probable, that had not 
this disease occurred, these embryos would in due season 
have been matured and deposited. 
Having shown that a particular change of feather follows 
the destruction of the sexual organs by disease, I shall pro- 
ceed to describe the effects produced upon both sexes of the 
common fowl, when obliteration of the same parts is effected 
by artificial means, that is to say, by an operation. 
The breeder of poultry, who practises the art of making 
capons, is apprized by the attempts of the young male bird to 
crow, that a sufficient enlargement of the testes has taken 
place to enable him to perform the operation of extraction 
with ease and certainty ; but this act completed, the bird 
never crows after. The comb and gills do not attain a size 
equal to those of other males not subjected to this operation ; 
the spurs appear, but remain short and blunt ; and the long 
narrow feathers of the neck and lower part of the back, so 
characteristic in the true male, put on an appearance in this 
bird, intermediate between the hackled appearance in the 
cock, and the ordinary web of the hen. 
The operation performed on the female of the common 
fowl is much more simple than might be expected. It con- 
sists in making a small incision through the thin skin of the 
flank on the left side ; the oviduct, which lies immediately 
within, is thus easily brought into view ; and it is then only 
necessary to cut away a small portion of it, that the continuity 
of the canal may be destroyed. The ova do not afterwards 
