Volume Ii Part 41 (1/2)

(710/1. The following letters to Sir J.D. Hooker and the late Mr.

Moggridge refer to Moggridge's observation that seeds stored in the nest of the ant Atta at Mentone do not germinate, though they are certainly not dead. Moggridge's observations are given in his book, ”Harvesting Ants and Trap-Door Spiders,” 1873, which is full of interesting details.

The book is moreover remarkable in having resuscitated our knowledge of the existence of the seed-storing habit. Mr. Moggridge points out that the ancients were familiar with the facts, and quotes the well-known fable of the ant and the gra.s.shopper, which La Fontaine borrowed from Aesop. Mr. Moggridge (page 5) goes on: ”So long as Europe was taught Natural History by southern writers the belief prevailed; but no sooner did the tide begin to turn, and the current of information to flood from north to south, than the story became discredited.”

In Moggridge's ”supplement” on the same subject, published in 1874, the author gives an account of his experiments made at Darwin's suggestion, and concludes (page 174) that ”the vapour of formic acid is incapable of rendering the seeds dormant after the manner of the ants,” and that indeed ”its influence is always injurious to the seeds, even when present only in excessively minute quant.i.ties.” Though unable to explain the method employed, he was convinced ”that the non-germination of the seeds is due to some direct influence voluntarily exercised by the ants, and not merely to the conditions found in the nest” (page 172). See Volume I., Letter 251.)

Down, February 21st [1873].

You have given me exactly the information which I wanted.

Geniuses jump. I have just procured formic acid to try whether its vapour or minute drops will delay germination of fresh seeds; trying others at same time for comparison. But I shall not be able to try them till middle of April, as my despotic wife insists on taking a house in London for a month from the middle of March.

I am glad to hear of the Primer (710/2. ”Botany” (Macmillan's Science Primers).); it is not at all, I think, a folly. Do you know Asa Gray's child book on the functions of plants, or some such t.i.tle? 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 gla.s.s 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 pa.s.s 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 nearly the same conclusions that you have done, though we have reached them by different routes. (713/2. ”The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom”: London, 1876.)

LETTER 714. TO F. DELPINO. Down, June 25th [1873].

I thank you sincerely for your letter. I am very glad to hear about Lathyrus odoratus, for here in England the vars. never cross, and yet are sometimes visited by bees. (714/1. In ”Cross and Self-Fertilisation,” page 156, Darwin quotes the information received from Delpino and referred to in the present letter--namely, that it is the fixed opinion of the Italian gardeners that the varieties do intercross. See Letter 709.) Pisum sativum I have also many times seen visited by Bombus. I believe the cause of the many vars. not crossing is that under our climate the flowers are self-fertilised at an early period, before the corolla is fully expanded. I shall examine this point with L. odoratus. I have read H. Muller's book, and it seems to me very good. Your criticism had not occurred to me, but is, I think just--viz.

that it is much more important to know what insects habitually visit any flower than the various kinds which occasionally visit it. Have you seen A. Kerner's book ”Schutzmittel des Pollens,” 1873, Innsbruck. (714/2.

Afterwards translated by Dr. Ogle as ”Flowers and their Unbidden Guests,” with a prefatory letter by Charles Darwin, 1878.) It is very interesting, but he does not seem to know anything about the work of other authors.

I have Bentham's paper in my house, but have not yet had time to read a word of it. He is a man with very sound judgment, and fully admits the principle of evolution.

I have lately had occasion to look over again your discussion on anemophilous plants, and I have again felt much admiration at your work.

(714/3. ”Atti della Soc. Italiana di Scienze Nat.” Volume XIII.)