156 
SEXUAL SELECTION : BIRDS. 
Part U. 
latter of this colour. The result would generally be 
the production either of a mongrel piebald lot, or more 
probably the speedy and complete loss of the pale-blue 
colour, for the primordial slaty tint would be trans- 
mitted with prepotent force. Supposing, however, that 
some pale-blue males and slaty females were produced 
during each successive generation, and were always 
crossed together ; then the slaty females would have, 
if I may use the expression, much blue blood in their 
veins, for their fathers, grandfathers, etc., will all have 
been blue birds. Under these circumstances it is con- 
ceivable (though I know of no distinct facts rendering 
it probable) that the slaty females might acquire so 
strong a latent tendency to pale-blueness, that they 
would not destroy this colour in their male offspring, 
their female offspring still inheriting the slaty tint. If 
so, the desired end of making a breed with the two 
sexes permanently different in colour might be gained. 
The extreme importance, or rather necessity, of the 
desired character in the above case, namely, pale-blue- 
ness, being present though in a latent state in the 
female, so that the male offspring should not be dete- 
riorated, will be best appreciated as follows : the male 
of Soemmerring’s pheasant has a tail thirty-seven inches 
in length, whilst that of the female is only eight inches ; 
the tail of the male common pheasant is about twenty 
inches, and that of the female twelve inches long. Now 
if the female Scemmerring pheasant with her short tail 
were crossed with the male common pheasant, there 
can be no doubt that the male hybrid offspring would 
have a much longer tail than that of the pure offspring of 
the common pheasant. On the other hand, if the female 
common pheasant, with her tail nearly twice as long as 
that of the female Soemmerring pheasant, were crossed 
with the male of the latter, the male hybrid offspring 
