sa Gray, who says
Hooker is very prosperous, and both are tremendously hard at work.
(743/1. "Hooker is coming over, and we are going in summer to the Rocky
Mountains together, according to an old promise of mine." Asa Gray to
G.F. Wright, May 24th, 1877 ("Letters of Asa Gray," II., page 666).)

LETTER 744. TO H. MULLER. Down, January 1st [1878?].

I must write two or three lines to thank you cordially for your very
handsome and very interesting review of my last book in "Kosmos,"
which I have this minute finished. (744/1. "Forms of Flowers," 1877. H.
Muller's article is in "Kosmos," II., page 286.) It is wonderful how you
have picked out everything important in it. I am especially glad that
you have called attention to the parallelism between illegitimate
offspring of heterostyled plants and hybrids. Your previous article in
"Kosmos" seemed to me very important, but for some unknown reason the
german was very difficult, and I was sadly overworked at the time, so
that I could not understand a good deal of it. (744/2. "Kosmos," II.,
pages 11, 128. See "Forms of Flowers," Edition II., page 308.) But I
have put it on one side, and when I have to prepare a new edition of my
book I must make it out. It seems that you attribute such cases as that
of the dioecious Rhamnus and your own of Valeriana to the existence of
two forms with larger and smaller flowers. I cannot follow the steps
by which such plants have been rendered dioecious, but when I read your
article with more care I hope I shall understand. (744/3. See "Forms of
Flowers," Edition II., pages 9 and 304. H. Muller's view is briefly that
conspicuous and less conspicuous varieties occurred, and that the former
were habitually visited first by insects; thus the less conspicuous form
would play the part of females and their pollen would tend to become
superfluous. See H. Muller in "Kosmos," II.) If you have succeeded
in explaining this class of cases I shall heartily rejoice, for they
utterly perplexed me, and I could not conjecture what their meaning was.
It is a grievous evil to have no faculty for new languages.

With the most sincere respect and hearty good wishes to you and all your
family for the new year...

P.S.--What interesting papers your wonderful brother has lately been
writing!

LETTER 745. TO W. THISELTON-DYER.

(745/1. This letter refers to the purchase of instruments for the
Jodrell Laboratory in the Royal Gardens, Kew. "The Royal Commission o