1919] FORESTRY. 151 



In consequence of the existence of communicntions between adjacent latex 

 vessels, it is concluded that lactiferous layers not opened by the tapping 

 operation can nevertheless in the long run have some influence on the latex 

 yield. Latex obtained from a tapping cut made at the base of the stem can 

 have proceeded from the stem, the main root, or the larger lateral branches 

 and roots. The latex of the leaves and secondary or tertiary lateral branches 

 can not proceed to the cut in view of the fact that a sufficient number of 

 continuous lactiferous vessels has not been developed. 



The effect of time intervals in rubber tapping', T. Fetch {Dept. Agr. Ceylon 

 Bui. 42 {1919), pp. S). — Results are given of experiments begun in 1912 to de- 

 termine the effect on yield of latex of tapping rubber trees at varying inter- 

 vals. 



The experiment, as a whole, shows that the yield of latex per tapping in 

 twice per week tapping is greater than thai in thrice per week tapping, but 

 that tapping once per week does not give a greater yield than tapping twice 

 per week. The greatest quantity of rubber was obtained from the most fre- 

 quent tapping, but the total yield obtained by tapping 3 times per week has 

 been only about 12 per cent greater than that obtained by tapping twice per 

 week. The percentage of rubber in the latex increased as the time interval 

 increased. The difference between the percentages of scrap obtained in tap- 

 ping twice per week and 3 times a week, respectively, is very small. 



Influence of a change in tapping surface on latex and rubber, O. de Vkies 

 (Arch. Rubbercult. Nederland. Indie, 3 {1919), No. 3, pp. 130-138) .—Experi- 

 ments conducted by the author indicate that when a change of tapping surface 

 is accompanied by a change of tapping system the properties of the rubber may 

 he expected to be affected to some extent. The difference is more marked 

 when changing to heavier tapping than when changing to milder tapping. It 

 is pointed out, however, that the change of tapping surface in ordinary estate 

 routine need not be regarded as a cause of variability, such as undoubtedly 

 is formed by the opening of a new cut or the reopening of a cut after a period 

 of rest. 



Rubber tapping experiments: Two cuts v. one cut, T. Fetch {Dept. Agr. 

 Ceylon Bui. J^l {1918), pp. 6). — Tapping experiments were started at Henarat- 

 goda in 1916 and continued for about 21 months in which the latex yield 

 from a single oblique cut on one quarter of the tree was compared with the 

 yield from two cuts on the opposite quarter of the tree. In one group of trees 

 the two cuts were made 1 ft. apart and in another group 2 ft. apart. In both 

 groups the lower cut was made about 15 in. above the ground at the same height 

 as the single cut on the opposite quarter. 



For the group of trees on which the two cuts were 1 ft. apart, the upper 

 cut at first appeared to stimulate a greater flow of latex from the lower cut 

 than the flow from the single cut on the opposite quarter. This apparently 

 stimulating effect disappeared in a few months, however, after which the flow 

 from the lower cut was less than from the single cut. In the other group of 

 trees with the two cuts spaced 2 ft. apart, the upper cut apparently exerted 

 a beneficial influence on the flow of latex from the lower cut as compared with 

 the single cut throughout the duration of the experiment. In both groups of 

 trees the yield from the upper cut averaged about half that of the lower. The 

 author is inclined to believe that the increased flow of the lower cut in the 

 second group of trees is due to a possible tendency of certain trees to yield 

 more latex on one side than on the other rather than to any stimulating in- 

 fluence of an upper cut. 



