CLIMATE OF PAEA RUBBER TREE. 45 



ANALOGY OF THE ASSAM RUBBER TREE. 



The fact that the production of rubber may fail under conditions 

 which permit the luxuriant growth of the trees is not new, since it was 

 recorded with reference to the Assam rubber tree as early as 1875, as 

 shown in the following - extract: 



The production of different kinds of caoutchouc in India continues to engage the 

 attention of the India Office and of this establishment. One fact in connection with 

 it which seems to require very careful consideration has been pointed out by Mr. 

 Mann in his report on the caoutchouc plantations in Assam. It is found that 

 although the Ficus elastica will grow with undiminished rapidity and luxuriance in 

 situations remote from the hills, it fails to yield caoutchouc. Mr. Mann concludes 

 that no greater mistake could be made than to start plantations of Ficus elastica in 

 any part of Bengal. It appears, therefore, judging from this case, that conditions 

 which may insure the successful growth of caoutchouc-yielding trees may not be 

 sufficient to determine their producing caoutchouc. « 



THE PARA RUBBER TREE IN HUMID LOCALITIES. 



Following the original publication of James Collins, in 1872, writers 

 on rubber have continued to emphasize the humidity of the forests of 

 the Amazon basin. 



The Amazon Valley is remarkable for uniformity of temperature and for regular 

 supply of moisture. From June to December is the dry season, and January to May 

 the wet. In the dry season in November there are a few occasional showers, and 

 during the wet season intervals of fine weather. * * * On the banks are dense 

 moist forests, with caoutchouc trees interspersed. Dr. Spruce, when at Barra, in 

 December, 1850, found that the rains had set in some weeks previous, and from 

 December 10 to the beginning of the following February only a single day occurred 

 without some rain. In February there were six fair days; in March, the most 

 rainy month, only one; and to April 18 but three days of fine weather. During 

 March the highest temperature was 84}°; many days it failed to reach as high as 80°. 



On the Solimoens, or upper Amazon, the sea breeze is not felt, and it is therefore 

 more stagnant and sultry. The whole of the country along its banks is covered 

 with one uniform, lofty, impervious, and humid forest. The soil nowhere sandy, 

 but always either a stiff clay, alluvium, or vegetable mold. The vegetation is very 

 prolific and the atmosphere densely vaporous. b 



It is difficult to explain why the heavy rains and overflowed rivers 

 have been dwelt upon with so much persistence and the six months of 

 dry weather left quite out of account, particularly since it has been 

 known from the first that the rubber is obtained in the dry season, and 

 Collins himself states that in the wet season the milk is poor in rubber, 

 or "too aqueous to allow of profitable collection. 1 ' 



The late Mr. Jenman, government botanist of British Guiana, has 



« Report on the Progress and Condition of the Royal Gardens at Kew during the 

 Year 1875, p. 7. 



& Collins, J. Report on the Caoutchouc of Commerce, p. 6. 



