ANTS AND PLANT-STRUCTURE 411 



and perhaps also in some cases to its flowers as 

 shown by Kerner by the presence of whole armies 

 of virulently - stinging ants whose very minute- 

 ness renders them the more formidable. In the 

 most remarkable plant-formicaria known those of 

 the Myrmecodia and Hydnophytum of the Malay 

 Archipelago the whole structure has been proved 

 to be hereditary, and we may therefore conclude 

 that in the Tococas of the Amazon, and other cases 

 in which the cavities inhabited by the ants are 

 constantly present, they are also hereditary. In 

 other cases, as Spruce himself states, they are 

 not so, being directly formed by the ants or being 

 abnormal growths due to their irritations. 



Spruce's error was in not recognising that the 

 ever-present variability in all the parts and organs 

 of plants furnished the material, and the survival of 

 the fittest the agency, by which these, as well as all 

 other specific modifications of plants, have been 

 brought about ; and that this is a far more powerful, 

 as well as a more exact and certain, mode of doing 

 so than the hereditary transmission of mutilations, 

 the effects of which would in many cases be the 

 reverse of beneficial. 



In my recent work, My Life (vol. ii. p. 64), I 

 give a letter from Spruce written shortly after the 

 paper was rejected, in which he explains his reasons 

 for refusing to alter his paper. Three years later 

 he wrote me another letter on an allied subject 

 the purport of aromatic leaves (printed at p. 65), 

 at the commencement of which he says : " Every 

 structure, every secretion of a plant is (before all) 

 beneficial to the plant itself. That is, I suppose, an 

 incontrovertible axiom." 



