DISEASES OF PLANTS. 345 



4 years of age. an average of 21S gui. of dry caoutchouc was produced per tree, 

 the stems and hirger branches both being tapped. One of these trees yielded 

 481 guj. and another 440 gua. 



With regrad to the spiral method of tapping, the average yield of caoutchouc 

 per single tapping was very small, ranging from 1.2 to 1.52 gm. of dry caout- 

 chouc. The author is of the opinion that it will not compare favorably, even 

 nu older trees, with the 3 former methods. The V-shape method is considered 

 worthy of further trial. 



The greatest average yield per single tapping was secured with the single 

 incision method over lai'ge surface, in which the average yield per tapping was 

 4.33 gm. of dry caoutchouc. 



On some rubber plants in South Madagascar, J. Costaxtix and H. Poisson 

 {Compt. RokJ. Acad. Sci. [Paris]. I'f', (1907). Xo. 19. pp. 1053-1055).— In 

 a recent tour through South Madagascar. M. Gaey collected several species of 

 caoutchouc, which are exploited to considerable extent by the natives. From 

 2 of these, locally known as Kokomba and Kidroa, the rubber Is said to be 

 extracted from the roots, which are gathered and exposed to the sun in order 

 to create a rapid coagulation of the latex, after which they are beaten with a 

 piece of hanl wood. The separated bark is then pounded to a pulp and the 

 mass 1)oiled with water, in order to eliminate the greater portion of the free 

 bark. The drying and boiling is repeated once or twice, after which the rubber 

 is made up into regular commercial balls. 



The authors describe these plants as new species of Mascarenhasia, AI. geaiji 

 and J/. A/V/ros'. respectively. Two species of Landolphia, discovered at the same 

 time, have been named L. mamolava and L. mamavo, and are also described. 



Rubber from a tuber at last (India Ruihcr World. 36 {1901), Xo. Jf. p. 300. 

 fin. 1). — A brief account is given of a tuberous rubber plant found in Portu- 

 guese West Africa, and reported by C. E. de Mello Geraldes. of the agronomical 

 institute at Lisbon. This plant is locally known as " ekanda " and " marianga " 

 and has been ascribed In* .J. Henriques to the natui'al order Asclepiadace:^. It is 

 said to flourish particularly in the sandy, treeless plateaus between the Kwanza 

 and Zambesi rivers, and is described in part as a stemless biennial plant with a 

 fleshy yellow tuberous root, sometimes turnip-shaped, but usually resembling a 

 flattened sphere, the entire substance of which is permeated with lactiferous 

 ducts. 



Rubber has been obtained from the '* ekanda " tubers by various crude experi- 

 mental processes, chiefly by slicing them and applying jtressure. Tubers 2 

 years old are referred to as attaining a diameter of 5i in. and a weight of H 

 His. a rubber yield of i per cent of the total weight resulted from the crude 

 processes. 



DISEASES OF PLANTS. 



The injurious effect of high germination temperatures upon the subse- 

 quent development of cereals, O. Appel and G. Gass.ner [Mitt. K. Biol. Aiist. 

 LiuiiJ II. Forstir.. 1907. Xo. -J, pp. .J-7. fiff. 1). — During the spring and summer of 

 IDOG the authors noticed in the summer grainfields about Dahlem a peculiar 

 diseased condition, which examination of material showed was not due either 

 to fungi or insects. The plants had lost their usual gi-een color and the lower 

 leaves were dead. It was suggested that the high temperature following the 

 seeding might have been the cause of the injury, and pot experiments were 

 undertaken with wheat, barley, and oats, one series of which was kept at 20 to 

 25° C. and the other from 5 to 7° during the period of germination. 



After 3 weeks' subjection to the above temperatures the plants at the higher 

 temperature showed the characteristic appearance noted above. Soil and fer- 



