REVIEWS 159 



The quality of the illustrations maintains a high standard, both the photographs 



and drawings being exceptionally clear and well chosen. In particular, the 



utilisation of perspective diagrams is an admirable safeguard against the growing 



tendency to view structure in the light of sections and to ignore interpretation in 



terms of the solid. 



E. J. Salisbury. 



Rubber Cultivation in Trinidad and Tobago. Report of the Special Com- 

 mittee of the Board of Agriculture, Trinidad. [Bulletin of the Department 

 of Agriculture, vol xvi. 1917, pp. 95-152.] 



RUBBER cultivation having been taken up more actively in Trinidad than in any 

 other West Indian island, this report of the industry is of particular interest, 

 especially as regards the conditions of rubber growing there compared with those 

 in the East. A Committee, including Mr. W. G. Freeman, Acting Director 

 of Agriculture, was appointed in 1916 "to investigate and report upon the present 

 position and prospects of rubber cultivation in Trinidad," and the report now 

 issued is a full and valuable account of the industry. 



Two species of rubber trees are chiefly grown in Trinidad, Hevea brasiliensis 

 (Para rubber) and Castilloa elastica (Central American rubber), and the report 

 shows that, as in the East, Para rubber is by far the most profitable kind to grow. 

 Both species were introduced into Trinidad about forty years ago, but unfor- 

 tunately preference was given at first to Castilloa, although no experimental 

 evidence was available at the time to justify this. It was not until the arrival of 

 the late Mr. Carruthers with his wide knowledge of the rubber industry in the East, 

 that the merits of Para rubber in Trinidad were recognised. The report states 

 that the rate of growth and the yield of latex in some plantations of Para rubber 

 in Trinidad are equal to those obtained on average estates in the East, although 

 the rainfall is often considerably less. The cost of production is reasonable and 

 leaves a good margin of profit with rubber at is. 6d. a pound. Hitherto the trees 

 have been planted too closely, and if the best results are to be obtained the 

 plantations will have to be thinned out until not more than a hundred trees are 

 left to the acre. Although the cost of weeding is less in Trinidad, other labour 

 charges are rather higher than in the East. In order to reduce the cost of 

 production it is suggested that the trees be tapped at intervals of four days, as 

 preliminary experiments show that the yield is as high under this system as when 

 the trees are cut every alternate day, notwithstanding that the highest yields in 

 the East result from tapping every day or on alternate days. Most of the 

 plantations in Trinidad are interplanted with some other crop, Robusta coffee 

 being considered the most suitable for Para rubber. Until the present this kind 

 of rubber has been less subject to root and bark diseases than in the East, but 

 this immunity is somewhat threatened by a leaf disease which has been trouble- 

 some in Guiana and has recently appeared in Trinidad. 



Castilloa, on the other hand, has been a disappointment. The report states 

 that the planting of this variety as a pure crop is not profitable, and that its 

 further planting, even as shade for cacao, is of doubtful benefit. Where already 

 established, Castilloa can be tapped with profit, although the yield is much less 

 than from Hevea. Unfortunately an efficient method of tapping Castilloa rubber 

 has not been discovered, and frequent tappings of adjacent areas of bark do not 

 give a steady flow of latex as in Hevea. At present the best way of tapping 

 Castilloa is to cut the bark with a cutlass two or three times a year ; most of the 

 latex coagulates on the trunk and the rubber is collected as scrap. 



