99 



NOTES ON PLANTS YIELDING RUBBER. I. 



Para Rubber (Hevea brasiHensis, Muell, Arg.) 

 Source . — Para rubber obtains the highest price in the market. It is 

 yielded by trees, which are chiefly Hevea brasiHensis, and IT. Spruceana. 



The trees are usually 60 feet in height when tapped, and they should 

 be at least 18 inches in circumference 



R. brasiliansis has trifoliate leaves, the leaflets being lanceolate 

 Locality. — These rubber trees grow in the forests on the Amazon and 

 its tributaries, and the provinces of Para and the Amazons have hitherto 

 been the chief source of the rubber supply. But as the trees are being 

 quickly destroyed by injudicious methods of tapping, collectors have 

 now to go beyond Para, and have penetrated even to Bolivia. 



Soil. — The soil in which the trees grow is deep and rich, mainly alluvi >\, 

 sometimes a stiff clay, sometimes a vegetable mould ; and it is frequently 

 inundated along the banks of the rivers. A large extent of low coun- 

 try on the banks of the Amazon is under water during the wet season. 



Temperature. — The temperature is very equable throughout the year, 

 ranging from 73° F. to 95°, though not generally above 87°, the mean 

 for the year being 81°. This condition of temperature is an important 

 one ; as is proved by the failure to grow these trees in Northern India, 

 where the nights of the winter months are cold, while the experiment 

 in Ceylon and South Burma is said to be a success. 



Rainfall. — The ramy season lasts from January or February to June or 

 July, the highest monthly rainfall of 15 inches being in April. The rest 

 of the year is called the dry season, when little rain falls, though there 

 is scarcely a week without some showers. It is at this time that the 

 rubber is collected. But in other districts it rains more or less all the 

 year round, and in these places collecting rubber is difficult and not 

 profitable. For, if the stem of the tree is wet, the milk spreads over 

 the bark instead of running into the cups ; moreover, rain falling into 

 the milk will prevent it from properly coagulating. The atmosphere is 

 excessively damp. 



Best Districts in Jamaica. — The Para rubber trees will probably only 

 succeed in J amaica in districts with an annual rainfall over 75 inches, at 

 elevations not at any rate greater than 2,000 feet. It is impossible to state 

 without experiments what the upward limits may be. The districts 

 in which experiments may well be made are parts of Portland, St. 

 Thomas in the East, St. Mary's, St. Ann's, Hanover, Westmoreland, 

 St. James's, St. Elizabeth, Manchester and Clarendon. A dry season 

 for collecting appears to be desirable, and possibly in this respect the 

 west end of the island possesses greater advantages than the east-end. 



Collection of Rubber. — Mr Robert Cross, who was employed by the 

 Government of India to obtain seeds and plants of rubber trees in 

 America, gives, in his Report to Government, the following accoun's 

 of the method employed in Para to collect the rubber : — 



" The collectors begins to work immediately at daybreak ; or as soon as 

 they can see to move about among the trees. They say the milk flows 

 more freely and in greater quantity at early morn. I do not attach 

 much importance to this statement, but I have recorded it. Another 

 and more probable reason is, that as rain often falls about two or three 



