ntially differ.

My book is horribly delayed, owing to the accursed index-maker. (207/2.
Darwin thoroughly appreciated the good work put into the index of "The
Variation of Animals and Plants.") I have almost forgotten it!

LETTER 208. TO T.H. HUXLEY. Down, January 30th [1868].

Most sincere thanks for your kind congratulations. I never received a
note from you in my life without pleasure; but whether this will be so
after you have read pangenesis (208/1. In Volume II. of "Animals and
Plants, 1868.), I am very doubtful. Oh Lord, what a blowing up I may
receive! I write now partly to say that you must not think of looking
at my book till the summer, when I hope you will read pangenesis, for I
care for your opinion on such a subject more than for that of any other
man in Europe. You are so terribly sharp-sighted and so confoundedly
honest! But to the day of my death I will always maintain that you have
been too sharp-sighted on hybridism; and the chapter on the subject in
my book I should like you to read: not that, as I fear, it will produce
any good effect, and be hanged to you.

I rejoice that your children are all pretty well. Give Mrs. Huxley the
enclosed (208/2. Queries on Expression.), and ask her to look out when
one of her children is struggling and just going to burst out crying. A
dear young lady near here plagued a very young child for my sake, till
it cried, and saw the eyebrows for a second or two beautifully oblique,
just before the torrent of tears began.

The sympathy of all our friends about George's success (it is the young
Herald) (208/3. His son George was Second Wrangler in 1868; as a boy
he was an enthusiast in heraldry.) has been a wonderful pleasure to
us. George has not slaved himself, which makes his success the more
satisfactory. Farewell, my dear Huxley, and do not kill yourself with
work.

(209/1. The following group of letters deals with the problem of the
causes of the sterility of hybrids. Mr. Darwin's final view is given in
the "Origin," sixth edition (page 384, edition 1900). He acknowledges
that it would be advantageous to two incipient species, if by
physiological isolation due to mutual sterility, they could be kept from
blending: but he continues, "After mature reflection it seems to me
that this could not have been effected through Natural Selection." And
finally he concludes (page 386):--

"But it would be superfluous to discuss this question in detail; for
with plants