i868 — iSSil II A R V ESI [NG \ N I 



sweet peas, and yet vari< ties, purposely grown ■ togetl er, i i 709 



hardly ever intercross. 1 his is a point which for years ha 



half driven me mad, ami 1 have disi it in my Var.oj 



Animals and Plants under Dom} I now suspect (and I wish 

 1 had strength to experimentise next spring) that from 

 changed climate both species arc prematurely fertilised, and 

 therefore hardly ever cross. When artificially crossed by 

 removal of own pollen in bud, the offspring are very vigorous. 



Farewell. — I wish I could compel you to go on worki: 

 at fertilisation instead of so insignificant a subject as the 

 commerce of the country ! 



You pay me a very pretty compliment at the beginning 

 of your paper. 



To J. D. Hooker. Letiei 



The following letters to Sir J. I). Hooker and the hue 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 death 

 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 point- out that the ancients 

 were familiar with the facts, and quotes the well-known fable of the ant 

 and the grasshopper, which La Fontaine borrowed from .Esop. Mr. 

 Moggridge (p. 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 sugges- 

 tion, and concludes (p. 174) that " the vapour of formic acid is incapable 



1 In the second edition (1875) of the Variation of Animals and Plants, 



Vol. I., p. 348, Darwin added, with respect to the rarity of spontaneous 

 crosses in Pisum : " I have reason to believe that this is due to their 

 >tiymas being prematurely fertilised in this country by pollen from the 

 same flower." This explanation is, we think, almost certainly applicable 

 to Lathyrus odoratus, though in Darwin's latest publication on the 

 subject he gives reasons to the contrary. See Cross and Self-Ft 

 ti ti sati on, p. 156, where the problem is left unsolved. Compare Letter 

 714 to Delpino, p. 391. In Life and letters, III., p. 261, the absence 

 of cross-fertilisation is explained as due to want of perfect adaptation 

 between the pea and our native insects. This is Hermann M tiller's 

 view: see his Fertilisation of Flowers, p. 214. See Letter 583, p. 250, 

 note 1 . 



