542 EXPERIMENT STATION EECOED. 



secured from various cultural experiments conducted, in the Prussian state for- 

 ests during the past 40 years. Tabular data are grouped and discussed with 

 reference to the following phases: The effect of various cultural methods, the 

 influence of various combinations of trees, a mixed stand of Pinus silvestris and 

 P. rigida as compared with a pure stand of P. silvestris, the effect of various 

 combinations of trees upon the resistance against crushing by snow, and the 

 effect of early strong thinning on the development of spruce stands. 



Some Irish larch plantations, J. H. Waddingham (Jour. Bd. Agr. [London^, 

 22 {1915), No. 3, pp. 231-235).— In continuation of a previous article (E. S. R., 

 31, p. 240) growth measurements are given for sample plats in a larch planta- 

 tion. The trees on different plats vary from 27 to 58 years of age. 



Pine tree culture in Nordland, F. Lindbebg {Skogsvdrdsfdr. TidsJcr., 1915, 

 Sup. 2, pp. 48, figs. 22). — An account is given of methods of reforesting pine 

 lands both by seeding and by planting. 



Hevea tapping results. Experiment Station, Peradeniya, 1911—1913, T. 

 Petch {Dept. Agr. Ceylon Bui. 12 {1914), PP- 28, pis. 2). — A progress report on 

 tapping experiments with Hevea rubber started in 1912, including a brief sum- 

 mary of previous worlv. The experiments are designed to show the difference 

 in yield and the effect on the trees of various systems of tapping which differ 

 in their time interval or space interval. Thus far no definite conclusions are 

 drawn. 



Hevea tapping- results. Experiment Station, Peradeniya, 1914, T. Petch 

 {Dept. Agr. Ceylon Bui. 11 {1915), pp. 16, pi. 1). — ^A further progress report on 

 the above noted investigation. 



Scientific tapping experiments with Hevea brasiliensis, A. W. K. De Jong 

 {Dept. Landh., Nijv. en Handel [Dutch East Iiidies], Meded. Agr. Chem. Lai)., 

 No. 10 {1915), pp. 83, figs. 39). — The first part of this work describes the various 

 experiments included in a comparison of tapping methods on a number of plats 

 of Hevea rubber trees. The second part describes similar comparative tests on 

 individual Hevea trees. 



Among the many results from the investigations as a whole it was found that 

 the method of making the cuts by individual tappers affected the yield of rub- 

 ber considerably. The thickness of the bast strip removed as well as the direc- 

 tion of the cut, that is from above, below, or vice versa, had no material influ- 

 ence on the yield of the cut. The maintenance of a continuous flow of latex 

 depended more on the restoration of capillary action than upon any peculiarity 

 of the latex itself. Neither the evaporation of the latex nor the drying out of 

 the bast had much effect on yield from cuts that were opened daily. 



Where cuts one above the other were not more than 50 cm. apart, the lower 

 cut averaged the greater yield of rubber. For greater distances than this no 

 effect was noticeable. Wounding the tree resulted in a stronger local formation 

 of rubber. Young bast gave more rubber than old. A left-hand cut appeared to 

 have some advantage over a right-hand cut, but there was very little difference 

 in yield between a " V " cut and a left-hand cut. 



A test of cuts of various slopes showed that the cut making the smallest angle 

 with the main tapping channel uses up the greatest amount of bast without giv- 

 ing a corresponding increase in rubber yield. Cuts made in a vertical direction 

 gave only about half the yield of a cut making an angle of 50° with the tapping 

 channel. It made no material difference whether cuts were renewed on the 

 upper or the lower side. The opening of one cut above another cut or alongside 

 another cut appeared to affect the yield of the first cut, provided the distance 

 between the two cuts was not great. No effect on yield was noticed from cuts 

 made on opposite sides of the tree. 



