I believe I have had cases from you.

But, if you believe in this, I wish you would give me a sentence to quote from you on this head.

There must, I think, be a good deal of truth in it; otherwise there could hardly be nearly distinct varieties under any species, for we should have instead a blending series, as in brambles and willows.
LETTER 49.

TO J.D.HOOKER.

July 13th, 1856.
What a book a devil's chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel works of nature! With respect to crossing, from one sentence in your letter I think you misunderstand me.
I am very far from believing in hybrids: only in crossing of the same species or of close varieties.