The Making of Species 
in accordance with all the observed results of 
castration. 
It is worthy of notice that the various features 
which characterise the sexes in sexually dimor- 
phic animals are not associated with any par- 
ticular organ or parts of the body, nor do they 
necessarily affect the same part in allied species. 
““We cannot say,” writes J. T. Cunningham, 
‘that any part of the soma (z.e. the body tissue) is 
specially sexual more than another part, except 
that such differences between the sexes are 
usually external. They usually affect the skin, 
and especially epidermic appendages, and the 
superficial parts of the skeleton, or whole limbs 
and appendages; or the difference may be one 
of size of the whole soma. In mammals and 
birds the male is often the larger, sometimes very 
much so, but there are cases in which the female 
is larger. There is no general rule.” 
Another important point is, that females, 
although they themselves show no trace of the 
male character, are capable of transmitting it to 
their progeny. This can be proved by crossing 
a hen pheasant with a cock barn-door fowl; the 
male offspring of the union display the plumes so 
characteristic of the cock pheasant. These can- 
not have been derived from the barn-door-fowl 
father; they must have come from the dull- 
coloured hen pheasant. 
In this connection we may mention the curious 
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