HUXLEY.
(92/1.

The point here discussed is one to which Mr.Huxley attached great, in our opinion too great, importance.) Down, January 11th [1860 ?].
I fully agree that the difficulty is great, and might be made much of by a mere advocate.

Will you oblige me by reading again slowly from pages 267 to 272.

(92/2.

The reference is to the "Origin," Edition I.: the section on "The Fertility of Varieties when crossed, and of their Mongrel Offspring" occupies pages 267-72.) I may add to what is there said, that it seems to me quite hopeless to attempt to explain why varieties are not sterile, until we know the precise cause of sterility in species.
Reflect for a moment on how small and on what very peculiar causes the unequal reciprocity of fertility in the same two species must depend.
Reflect on the curious case of species more fertile with foreign pollen than their own.