i868 1881] HARVESTING ANTS 391 



To J. Traherne Moggridge. Letter 712 



Down, March loth, 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 1 ; it will be a very strange 

 fact if you can prove this. 



To H. Muller. Letter 7 , 3 



Down, May 3Oth, 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, 2 which I 

 have finished. 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 3 I have arrived on many 

 points at nearly the same conclusions that you have done, 

 though we have reached them by different routes. 



To F. Delpino. 



Down, June 25th [1873]. ;er 



I thank you sincerely for your letter. I am very glad to 

 hear about LatJiyrus odomtus, for here in England the vars. 

 never cross, 4 and yet are sometimes visited by bees. 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 



1 Certain seeds pass through a resting period before germination. 

 See Pfeffer's Pflanzenphysiologie, Ed. I., Vol. II., p. m. 



2 "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 (Feb. 6th, 1882) is almost the last 

 of Mr. Darwin's writings. See Life and Letter s^ p. 281. 



3 The Effects of Cross and Self- Fertilisation in the Vegetable Kingdom : 

 London, 1876. 



4 In Cross and Self-Fertilisation, p. 156, Darwin quotes the informa- 

 tion 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, 



