74 MY LIFE [Chap. XXVII] 



The special points of interest in the above letter are its 

 complete confirmation of the views derived from European 

 plants, as to use of the colours of fruits in indicating those 

 which are edible for birds or arboreal mammals, while the 

 few exceptions as regards colour are of those large and very 

 sweet fruits whose attractions are sufficient without the signal 

 of bright colour. Again, the very frequent occurrence of 

 acrid or poisonous juice or milk in the bark and leaves, 

 protecting the young shoots and trees from herbivorous 

 animals, combined with perfectly innocuous and often agree- 

 able fleshy or juicy fruits in order to assist in their dispersal, 

 so clearly implies a selective agency in two opposite directions 

 in the same species, as almost to amount to the required 

 demonstration of the existence of natural selection. 



I cannot forbear calling attention to the extremely careful 

 wording and punctuation of these letters, written from a sick 

 couch, and of which I have not altered a word or a comma. 

 The clearness and accuracy with which the information is 

 conveyed fittingly corresponds with the writer's careful obser- 

 vation of every aspect and detail of plant life. Had his health 

 permitted more continuous work for a few years longer, he 

 would probably have given us a volume upon all the chief 

 aspects and relations of the vegetation of the forests and 

 mountains of equatorial America, which would have been of 

 the greatest scientific and popular interest. 



