fully test the procreative power of these hens. Now, if
you are inclined to get a Spanish cock and a couple of white Silk hens,
I shall be most grateful to hear whether the offspring breed well: they
will prove, I think, not hardy; if they should prove sterile, which I
can hardly believe, they will anyhow do for the pot. If you do try this,
how would it do to put a Silk cock to your curious silky Cochin hen, so
as to get a big silk breed; it would be curious if you could get silky
fowl with bright colours. I believe a Silk hen crossed by any other
breed never gives silky feathers. A cross from Silk cock and Cochin Silk
hen ought to give silky feathers and probably bright colours.

I have been led lately from experiments (not published) on dimorphism
to reflect much on sterility from hybridism, and partially to change
the opinion given in "Origin." I have now letters out enquiring on the
following point, implied in the experiment, which seems to me well worth
trying, but too laborious ever to be attempted. I would ask every pigeon
and fowl fancier whether they have ever observed, in the same breed, a
cock A paired to a hen B which did not produce young. Then I would get
cock A and match it to a hen of its nearest blood; and hen B to its
nearest blood. I would then match the offspring of A (viz., a, b, c, d,
e) to the offspring of B (viz., f, g, h, i, j), and all those children
which were fertile together should be destroyed until I found one--say
a, which was not quite fertile with--say, i. Then a and i should be
preserved and paired with their parents A and B, so as to try and get
two families which would not unite together; but the members WITHIN each
family being fertile together. This would probably be quite hopeless;
but he who could effect this would, I believe, solve the problem of
sterility from hybridism. If you should ever hear of individual fowls or
pigeons which are sterile together, I should be very grateful to hear of
the case. It is a parallel case to those recorded of a man not impotent
long living with a woman who remained childless; the husband died, and
the woman married again and had plenty of children. Apparently (by
no means certainly) this first man and woman were dissimilar in their
sexual organisation. I conceive it possible that their offspring
(if both had married again and both had children) would be sexually
dissimilar, like their parents, or sterile together. Pray forgive my
dreadful writing;