But can you conceive that any individual plants of the primrose and cowslip which happened to be mutually rather more sterile (i.e.
which, when crossed, yielded a few less seed) than usual, would profit to such a degree as to increase in number to the ultimate exclusion of the present primrose and cowslip?
I cannot.
My son, I am sorry to say, cannot see the full force of your rejoinder in regard to second head of continually augmented sterility.

You speak in this rejoinder, and in Paragraph 5, of all the individuals becoming in some slight degree sterile in certain districts: if you were to admit that by continued exposure to these same conditions the sterility would inevitably increase, there would be no need of Natural Selection.

But I suspect that the sterility is not caused so much by any particular conditions as by long habituation to conditions of any kind.

To speak according to pangenesis, the gemmules of hybrids are not injured, for hybrids propagate freely by buds; but their reproductive organs are somehow affected, so that they cannot accumulate the proper gemmules, in nearly the same manner as the reproductive organs of a pure species become affected when exposed to unnatural conditions.
This is a very ill-expressed and ill-written letter.

Do not answer it, unless the spirit urges you.