1919] DISEASES OF PLANTS. 449 



bark is not sufficient when the cambium is affected, since tho diseased cambium 



must be scraped away. 



Tapping on renewed bark, T. PrrCH (Trop. Apr. [Ceylon], 51 (1918), No. 5, 

 pp. 293-296, fig. l). — Tabular results are given on a comparative test of robber 



yields Obtained from renewed bark of differenl ages. The test was started at 

 tbe Gangaruwa Experiment Station in July, 1916, and continued for 2 years. 

 Trees on which the renewed bark was r> years months old at the beginning 

 of the experiment yielded 8,601 gut. of rubber per tree for the 2 years; renewed 

 bark 4 years 8 months at the beginning of tapping yielded 2,828 gm. per tree; 

 and renewed bark 3 years 7 mouths at the beginning of tapping yielded 2,629 

 gm. per tree. 



The African oil palm, its possibilities in Malay, B. J. Eaton and F. G. 

 Spring (Ayr. Bui. Fed. Malay States, 6 (1918), \'o. 11, pp. $98-512 ). -An ac- 

 count of the African oil palm (Kiwis yuincensis), with reference to its distri- 

 bution, botany, cultural requirements, estimated yields of palm oil and palm- 

 kernel oil, and methods and machinery used in extracting oil. Analyst- are 

 given of palm fruit of different parts of western Africa, aud the industry is 

 considered with reference to its development in Malay. 



A note on the occurrence and method of formation of the resin (yacca gum) 

 in Xanthorrhcea quadrangulata, T. G. B. Osborn (Trans. Roy. 8oe. So. Au.st., 

 40 (1916), pp. 1-8, pis. 3, figs. 3). — A preliminary study of resin formation In 

 A', quadrangulata, an Australian grass tree, led the author to conclude that the 

 resin Is an Intracellular secretion, principally of the peripheral cortical cells 

 of the stem. The resin so formed is molded by pressure between the persistent 

 leaf bases clothing the stem. It becomes viscous at sun heat, flows to a 

 certain extent, and destroys the original cellular matrix. There appears to be 

 little likelihood of collecting the resin other than by destroying the tree. 

 The macroscopic and microscopic structure of the stem and leaf bases are 

 described. 



DISEASES OF PLANTS. - 



The relation of phytopathologists to plant disease survey work, G. R. 

 Lyman (Phytopathology, 8 (1918), No. 5, pp. 219-228; abs. in 8 (1918). No. 2. 

 pp. 78, 79). — An outline is given of some of the work of the plant disease survey 

 which has been organized in the United States Department of Agriculture. 



[Report of] the botany and bacteriology department, D. B. SwiNOLE (Mon- 

 tana Sta. Rpt. 1917, pp. 236, 237). — A report of progress is given on the various 

 lines of work, including the studies of the injury to foliage by spraying and to 

 roots by adding arsenicals. 



In the study of the brown bark spot of fruit trees the cause has not been 

 determined, but the investigations so far have given indications that the dis- 

 ease is not due to a pathogenic organism. Spraying experiments for the con- 

 trol of plum pockets caused by Taphrina communis, though carried on in a 

 very unfavorable season, gave satisfactory results, and the author recommends 

 a single application of lime-sulphur just before the flower buds open. Notes 

 are given on potato diseases, particular attention having been paid to the wilts 

 and rots caused by species of Fusarium and to the bacterial disease of potatoes 

 known as blackleg. 



Seed treatment control and overwintering of cucumber angular leaf spot, 

 W. W. Gilbert and M. W. Gardner (Phytopathology, 8 (191S). No. 5, pp. tS9- 

 233, fig. 1).— It having been shown by Carsner (E. S. R., 40, p. 250) that the 



