o you know Asa Gray's
child book on the functions of plants, or some such title? It is very
good in giving an interest to the subject.

By the way, can you lend me the January number of the "London Journal of
Botany" for an article on insect-agency in fertilisation?

LETTER 711. TO J. TRAHERNE MOGGRIDGE. Down, August 27th, 1873.

I thank you for your very interesting letter, and I honour you for your
laborious and careful experiments. No one knows till he tries how many
unexpected obstacles arise in subjecting plants to experiments.

I can think of no suggestions to make; but I may just mention that I
had intended to try the effects of touching the dampened seeds with the
minutest drop of formic acid at the end of a sharp glass rod, so as to
imitate the possible action of the sting of the ant. I heartily hope
that you may be rewarded by coming to some definite result; but I fail
five times out of six in my own experiments. I have lately been trying
some with poor success, and suppose that I have done too much, for I
have been completely knocked up for some days.

LETTER 712. TO J. TRAHERNE MOGGRIDGE. Down, March 10th, 1874.

I am very sorry to hear that the vapour experiments have failed; but
nothing could be better, as it seems to me, than your plan of enclosing
a number of the ants with the seeds. The incidental results on the power
of different vapours in killing seeds and stopping germination appear
very curious, and as far as I know are quite new.

P.S.--I never before heard of seeds not germinating except during a
certain season; it will be a very strange fact if you can prove this.
(712/1. Certain seeds pass through a resting period before germination.
See Pfeffer's "Pflanzenphysiologie," Edition I., Volume II., page III.)

LETTER 713. TO H. MULLER. Down, May 30th, 1873.

I am much obliged for your letter received this morning. I write now
chiefly to give myself the pleasure of telling you how cordially I
admire the last part of your book, which I have finished. (713/1.
"Die Befruchtung der Blumen durch Insekten": Leipzig, 1873. An English
translation was published in 1883 by Prof. D'Arcy Thompson. The
"Prefatory Notice" to this work (February 6th, 1882) is almost the last
of Mr. Darwin's writings. See "Life and Letters," page 281.) The whole
discussion seems to me quite excellent, and it has pleased me not a
little to find that in the rough MS. of my last chapter I have arrived
on many points at n