362 NOTES OF A BOTANIST CHAP. 



tation in all these and in hundreds of other cases 

 is invariably modified after the same fashion by the 

 colour of the waters. How it became what it is, 

 and how it came there at all, are questions not to 

 be discussed here. 



After what has been said, it is scarcely necessary 

 to add that many species of plants which grow down 

 to the very coast in Guayana exist also in the 

 Peruvian province of Maynas that is, at the eastern 

 foot of the Andes, and even up to a height of a few 

 thousand feet in those mountains e.g. Humboldt's 

 Willow (Salix hnmboldtiana, W.) and the Cannon- 

 ball tree (Couroupita guianensis, Aubl.), called 

 Aia-uma or Dead Man's Head in Maynas ; while 

 the proportion of Orinoco plants repeated on the 

 Amazon is much greater than that of the plants of 

 South Brazil. Nor does this uniformity of char- 

 acter, and the constant recurrence of certain species, 

 preclude the possibility of the flora being wonder- 

 fully rich ; for I have calculated that by moving 

 away a degree of either latitude or longitude I 

 found about half the species different ; while in the 

 numerous caatingas I have explored I always found 

 a few species in each that I never saw again, even 

 in other caatingas. 



THE RELATIONS OF PLANTS AND ANIMALS 



The importance of inquiries of this class is 

 obvious, even from a zoological point of view ; for 

 that an animal should flourish in any region it must 

 there find suitable food ; and there is perhaps no 

 part of the world where so large a proportion of the 

 animals is so directly vegetarian in its diet. I have 



