stralian Mastodon as a proof of the remarkable
geographical distribution of the Proboscidia. In a subsequent discussion
he frankly abandoned it, in consequence of the doubts then urged
regarding its authenticity. (See footnote, page 101, in Falconer's paper
"On the American Fossil Elephant," "Nat. Hist. Review," 1863.)), and am
heartily glad you attacked the Australian Mastodon. I never did or could
believe in him. I wish you would read my little Primula paper in the
"Linnean Journal," Volume VI. Botany (No. 22), page 77 (I have no copy
which I can spare), as I think there is a good chance that you may have
observed similar cases. This is my real hobby-horse at present. I have
re-tested this summer the functional difference of the two forms in
Primula, and find all strictly accurate. If you should know of any cases
analogous, pray inform me. Farewell, my good and kind friend.

LETTER 146. TO J.D. HOOKER.

(146/1. The following letter is interesting in connection with a letter
addressed to Sir J.D. Hooker, March 26th, 1862, No. 136, where the
value of Natural Selection is stated more strongly by Sir Joseph than by
Darwin. It is unfortunate that Sir Joseph's letter, to which this is a
reply, has not been found.)

Down, November 20th [1862].

Your last letter has interested me to an extraordinary degree, and your
truly parsonic advice, "some other wise and discreet person," etc.,
etc., amused us not a little. I will put a concrete case to show what
I think A. Gray believes about crossing and what I believe. If 1,000
pigeons were bred together in a cage for 10,000 years their number
not being allowed to increase by chance killing, then from mutual
intercrossing no varieties would arise; but, if each pigeon were a
self-fertilising hermaphrodite, a multitude of varieties would
arise. This, I believe, is the common effect of crossing, viz., the
obliteration of incipient varieties. I do not deny that when two marked
varieties have been produced, their crossing will produce a third
or more intermediate varieties. Possibly, or probably, with domestic
varieties, with a strong tendency to vary, the act of crossing tends
to give rise to new characters; and thus a third or more races, not
strictly intermediate, may be produced. But there is heavy evidence
against new characters arising from crossing wild forms; only
intermediate races are then produced. Now, do you agree thus far? if
not, it is no use arguing; we must come to s