328 TRANSACTIONS OF SECTION K. 



is remarkable. It is extensively used for planting in London and other towns 

 in this country, and also in Europe and North America, ' as it has been found 

 to surpass all other trees in its powers of resistance to drought, smoke, and 

 other unfavourable conditions of soil and atmosphere.' 



In the Tropics breeding experiments in the case of India-rubber trees are 

 likely to prove of great value. In the meantime, selection of seed from the 

 best trees is being carefully carried out in the hope of increasing the general 

 yield of the plantations. In Java the proportion of alkaloids in the bark of 

 introduced Cinchona tre«s (yielding quinine) have nearly doubled by careful 

 selection on these lines. In the case of rubber trees, which are_ known to 

 possess marked individuality in regard to the amount cf latex which can be 

 drawn from them, it is suggested that seed for planting should be taken only 

 from trees selected for their high-yielding capacity. In fact, the selection of 

 seed bearers may play an important part in the future development and_ per- 

 manence of the rubber industry. Where good seed is not readily available 

 Lock has suggested that the best trees might be raised from cuttings. 



Plant-breeding experiments with India-rubber trees have already been 

 attempted, but they are not likely to be of much value if they are confined 

 to empirical and haphazard lines. It is suggested that they should be carried 

 on at well-staffed and well-equipped stations devoted to breeding and kindred 

 problems. Such stations should be established in each of the main rubber- 

 growing regions. Work of this kind must be lengthy and complex, but it is 

 absolutely essential to ensure the safety of an industry which i? estimated to 

 be of the annual value in the Middle East of about fifty millions sterling. The 

 Agricultural Department in Ceylon, which is fully alive to the fundamental 

 importance of selection and breeduig India-rubber trees, has already taken some, 

 action in the matter. For instance," at the Heneratgoda Gardens there are fifty 

 Hevea trees whose individual latex-yield has been recorded for every tapping 

 since June 1908. One tree marked No. 2 has yielded an amount of rubber far in 

 excess of any other tree. In 1912 seeds and stumps taken from this tree have 

 been established on a plot of three acres at the Experiment Station at Peradeniya. 

 ■Wlien the trees are fit for tapping and the good yielders are determined the 

 others will be cut out and the remainder reserved for seed purposes. 



Another investigation in hand is to determine whether the latex-yielding 

 quality of Hevea trees can be associated with any definite botanical characters 

 and to what extent such characters are tran,smittible. Twenty trees of the 

 same age growing in a four-acre block have been selected for differences 

 in leaf "and bark characters. These are all tapped on the same system, and 

 the yield of rubber from each tree is recorded separately for each tapping.' 



The value of these and other experiments of a like nature may be realised 

 when, accordinsr to Varnet, quoted by Johnson, the yield of rubber from 

 different trees of Hevea growing under similar conditions in the same plantation 

 may vary as resards volume of latex from 4 to 48. and in percentage of weight 

 of dry rubber from 1.286 to 14.164.* 



Bateson a few years ago expressed the opinion that nowhere is the need for 

 wide views of our problems more evident than in the study of plant diseases. 

 Hitherto, he said, ' this side of agriculture and horticulture, though full of 

 possibilities for the introduction of scientific methods, has been examined only 

 in the crudest and most empirical fashion.'' Since then some advance has 

 been made in the morbid physiology of plants, but such work to be carried to a 

 successful and practical issue demands careful experiments carried on con- 

 tinuously by specialists for many years. 



Keeble suggests that "the professional mycologist is accustomed to confine 

 his attention too exclusively to the active agent of the disease,' vtrhile, on the 

 other hand, 'the professional cultivator gives habitually great weight to the 

 possibility of preserving plants from disease by improving his methods of 

 cultivation. Both are right, yet neither is wholly wise, and there is much room 

 for » race of mycologists who not only discover how to cure plants but know 



' Kew Bull. 1917, 118. 



8 Jmir d'Agric. Trovicah, 1907. 



' 'Address, Section M., 1911. 



