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 (i.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. Theise 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 

 336 ' 



