406 BOTANY [Chap. XI 



Letter 729 branches of C. purpureus. If I understand rightly your letter, 

 you consider the tuft of small shoots on one side of the 

 sporting C. alpinus from Weirleigh as C. purpureus ; but these 

 shoots are certainly those of C. Adami. I earnestly beg you 

 to look at the specimens enclosed. The branch of the true 

 C. purpureus is the largest which I could find. If C. Adami 

 was sold to your brother as C. purpureus, everything is ex- 

 plained ; for then the gardener has grafted C. Adami on 

 C. alpinus, and the former has sported in the usual manner ; 

 but has not sported into C. purpureas, only into C. alpinus. 

 C. Adami does not sport less frequently into C. purpureus 

 than into C. alpinus. Are the purple flowers borne on mode- 

 rately long racemes? If so, the plant is certainly C. Ada7ni, 

 for the true C. purpureus bears flowers close to the branches. 

 I am very sorry to be so troublesome, but I am very anxious 

 to hear again from you. 



C. purpureus bears " flowers axillary, solitary, stalked." 

 P.S. — I think you said that the purple [tree] at Weirleigh 

 does not seed, whereas the C. purpureas seeds freely, as you 

 may see in enclosed. C. Adami never produces seeds or pods. 



Letter 730 To E. Hackel. 



The following extract refers to Darwin's book on Cross and Self- 

 Fertilisation. 



Nov. 13th, 1875. 



I am now busy in drawing up an account of ten years' 

 experiments in the growth and fertility of plants raised from 

 crossed and self-fertilised flowers. It is really wonderful what 

 an effect pollen from a distinct seedling plant, which has been 

 exposed to different conditions of life, has on the offspring in 

 comparison with pollen from the same flower or from a 

 distinct individual, but which has been long subjected to the 

 same conditions. The subject bears on the very principle of 

 life, which seems almost to require changes in the conditions. 



Letter 731 To G. J. Romanes. 



The following extract from a letter to Romanes refers to Francis 

 Darwin's paper, "Experiments on the Nutrition of Drosera rotundifolia." 

 Linn. Soc. Journ. [1878], published 1880, p. 17. 



August 9th [1876]. 

 The second point which delights me, seeing that half a 

 score of botanists throughout Europe have published that the 



