FORESTRY, 241 



ISl ; .'/, pp. 181-191, fiffs. 12). — In these experiments special attention was paid 

 to a comparison of the pricker system of tapping with various systems of 

 linife tapping. 



The autlior found that the priclcer system does not yield a greater quantity 

 of latex than knife tapping and that where the pricker system is used bark 

 renewal is usually retarded and irregular. The renewal of the latex system In 

 the tapr)ing area is interfered with. In knife tapped trees the renewal of the 

 bark is much more rapid, and there appears to be little danger of exhausting 

 the reserve material providing the trees are growing sufficiently far apart to 

 allow the crown of the ti'ees to develop freely. As a further precaution against 

 exhaustion of the reserve material, it is advised that the trees should not be 

 tapped at times during the year when there are no appreciable assimilation 

 activities, as during the yellowing and falling of the leaves, during the dormant 

 period, and in the first days of leaf renewal. 



Report of the svtperintendent of the rubber substation, V*^. A. Anderson 

 {Hawaii Sla. Rpt. 1912, pp. SS-91). — Attention has been directed during the 

 year chiefly toward the development of a system of tapping Ceara trees that 

 would yield the largest amount of rubber per unit of labor without injury to 

 the tree, and in curing the product in such a way as to make it satisfactory to 

 manufacturers. 



No satisfactory incision method for tapping the Ceara tree without removing 

 the outer bark has thus far been found. The pricker method of tapping was 

 found to be inferior to knife incisions, both as to yield and in recovering the 

 flow of latex at subsequent tappings. Two fundamental facts were demon- 

 strated with reference to knife incisions: First, that a horizontal knife incision 

 gives better results than a vertical incision; second, that the portion of the tree 

 just above the ground to a height of about 6 in. yields rubber in much larger 

 quantities than any other portion. The second of these facts was utilized in 

 the development of a system here described, which has given better results in 

 proportion to the labor involved than any other. By this method the bark is 

 removed to a height of about 6 in. and cuts made with a very thin knife blade 

 from the ground to the top of this stripped surface. The latex is allowed to 

 flow to the ground and coagulate, the rubber being collected the following day 

 and new cuts made at the same time. The average daily yield for 100 acres 

 during G months' tapping was somewhat less than 4 lbs. Attempts to continue 

 this method higher up on the tree have not thus far proved successful, and tests 

 were started with another system of tapping here described. 



It is concluded from the work so far done that the above system is the 

 cheapest and most desirable where there are sufficient trees to be tapped to 

 furnish work for all the labor available. . The product, though very unattractive 

 as it comes from the field, can when properly washed and vacuum dried be 

 turned into rubber of the first class without too great expense. 



[Analyses of Hawaiian rubber], W. McGeorge (Hairaii fSta. Rpt. 1912. pp. 

 62, 63). — Comparative analyses of Hawaiian (Ceara) crepe and biscuit rubber 

 and INIalay crepe rubber are here reported. The Hawaiian rubber contains a 

 somewhat higher percentage of ash and resins than the Malay rubber, the resin 

 increase probably being due to a difference in the age of the trees. 



Wild lettuce rubber, C. P. Fox (Jour. Indus, and Engin. Chcin.. 5 (1913), 

 No. 6, pp. Jill, IpS). — ^A study of the chemical composition of 2 species of wild 

 lettuce, Lactuca canadensis and L. scariola, with special reference to their 

 possibilities as rubber producers. 



L. canadensis was found to contain 2.19 per cent and L. scariola 1.5S per 

 cent of a good quality of rubber. Both species also contained about 12 per 

 cent of a waxy acetone soluble body. L, canadensis contained a bitter prin- 



