ON THE DISTRIBUTION OF FOKESTS IN INDIA. 1 05 



A far more limited range of distribution has the Caoutchouc tree 

 (Flcus elastica), a tree which is frequently grown in conservatories 

 and drawing-rooms in this country aud on the Continent ; so much 

 so, that in Germany it goes by the name of the Berlin weed. Its 

 milky juice yields a description of India-rubber, not equal to the 

 excellent Para rubber, the product of an altogether different kind of 

 tree in Brazil, but which may be capable of improvement by a more 

 careful method of collection. In India this Caoutchouc tree has only 

 been found in the moist forest skirting the Eastern Himalaya from 

 Sikkim to Assam, and at the foot of the Khasia and Cachar hills. 

 A humid atmosphere, and equable temperature throughout the year, 

 seem to be the principal conditions of its free growth. The mean 

 temperature in the stations nearest to the caoutchouc forests is 

 between 60° and 65° in the cold season, and 80° and 85° in the 

 three hottest months. 



The conditions of existence under which the Deodar grows at the 

 north-western end of the Himalayan range are altogether different. 

 To begin with, it demands a certain elevation ; as a rule it does not 

 thrive in the north-west Himalaya under 4000 feet, but it ascends 

 to 10,000 and at times to 12,000 feet. As to mean temperature, a 

 range between 35° and 50° in the cold season, and 65° to 75° during 

 the three summer months, seems to suit it best. As regards 

 humidity, the Indian cedar does not go beyond certain limits of 

 drought and moisture. In the Sutlej and other Himalayan valleys 

 it disappears where the arid region commences, although the con- 

 ditions of soil, temperature, and elevation are not unfavourable. 

 Again, it is wanting in the Eastern Himalaya, where the rainfall 

 exceeds 100 inches. The Deodar is so closely allied to the Cedars 

 of Lebanon, the Taurus, and the Atlas mountains, that botanists 

 find it difficult to keep them distinct as species. A close comparison 

 of the climatic conditions under which these western cedars grow, 

 with the climate of the north-west Himalaya, may lead to interest- 

 ing results regarding the history of the spread of these beautiful 

 and useful trees. It is not, however, climate, soil, and the action of 

 man in historic times alone, which determine the area over which 

 plants or trees are actually found at the present time; other far 

 more remote causes have been at work, the study of which forms the 

 most interesting part of botanical geography. The forester, how- 

 ever, has to take things as they are, and to him the most important 

 point is to ascertain the conditions most favourable for a vigorous 

 growth of those trees which pay best, and which yield the largest 



VOL. VII. PART I. II 



