1893. EVOLUTION IN THE GUIANA FOREST. 39 



he found himself lost in the forest. The perspiration streams from 

 the new-comer, and unless he is enthusiastic in pursuit of his hobby 

 he is glad to find himself again on the river. Where the land is low, 

 pools of ruddy-brown water occupy the hollows between the im- 

 mense buttresses of every tree, while here and there small streams 

 wind in and out among them. The fallen leaves and other debris 

 form an oozy kind of peat, obviously giving colour to the water, which 

 is the same in almost every creek and river in Guiana. 



It is generally considered that the forest is unhealthy for man. 

 Residents along river banks suffer more or less from intermittent 

 fevers, which often leave them after a change to the coast. In open- 

 ing up new land by clearing, it is notorious that strangers suffer much 

 while the work is going on. Swamps are also unhealthy for strange 

 plants. Few cultivated fruit trees can endure inundations for even a 

 day or two. Yet, under these conditions, the trees of the forest 

 thrive. They have obviously become accustomed to environment 

 such as would be dangerous to nearly all others. Is it not possible 

 that what is dangerous to a plant is just as injurious to man, unless 

 he has protected himself in some way ? Also that there may be 

 lessons to learn from the way trees have warded off the danger ? 



It is an undoubted fact that the forest giants of Guiana have 

 evolved contrivances to prevent the development of low fungi. The 

 most common of these is a thick bark containing tannin. This tannin 

 IS Nature's great antiseptic. It is found in all the waters of the forest 

 and swamp, and accounts for that great difference which exists 

 between the clear brown bog water and that seat of infection the 

 stagnant pool. In towns and villages ordinary rain-water, if allowed 

 to remain in open trenches, never resembles in its antiseptic properties 

 that of the forest. The Indian has gone to the forest and learnt a 

 lesson. When suffering from ulcers he scrapes the inner bark of 

 some tree and applies it to the sore with most beneficial results. 



Besides this, many other secretions have been developed. One 

 of the most extraordinary is, perhaps, the milky juice which dries into 

 india-rubber and gutta-percha. It is well-known that the Hevea 

 grows only in places that are periodically inundated, and this 

 characteristic is also strikingly exemplified in the tree which produces 

 balatta, the gutta-percha of Guiana. It may be objected that some of 

 the species of Ficus, which have similar juices, do not necessarily 

 belong to the swamp, but perhaps their ancestors lived under 

 different conditions. These secretions are so evidently fitted for pro- 

 tection against water that we can hardly conceive of them in any 

 other connection. 



Then there is another large class, the gum-resins and oleo-resins, 

 also common in Guiana. Gum animi, the incense gum from the 

 hyawa (Idea), and balsam copaiba are the best known examples. 

 The species of Copaifera are characterised by their thick bark, from 

 which the Indian wood-skin canoes are made, and which are preserved 



