DISEASES OF PLANTS, 741 



elastica, and " Marodi " vine rubber from southern Nigeria, rubber of Ficus 

 vogelii from tlie (lambia, and of Vahea rubber, a species of Landolpbia from 

 Seychelles. 



Treatment and transformation of Eucalyptus globulus forests, H. Mulleb 

 (Rev. Secc. Agron. Univ. Montevideo, 1908, No. Jf, pp. 95-106). — In this article 

 the author outlines methods for the silvical treatment and exploitation of E. 

 glohnlus forests in the department of Montevideo, with a view of obtaining 

 the greatest percentage of timber possible and of substituting other more useful 

 species without lessening the production of the forests in the meanwliile. 



On the elastic substance occurring on the shoots and young leaves of 

 Eucalyptus corymbosa and some species of Angophora, II. G. Smith (Jour. 

 and Proc. Roy. 8oc. N. 8. Wales, 1,2 (1908), pp. 133-lU, fig. i).— An investiga- 

 tion of tlie properties and composition of the elastic substance occurring on the 

 shoots and young leaves of Eucalyptus corymhosa, Angophora lanceolata, and 

 A. intermedia leads to the conclusion that it is a good form of caoutchouc. The 

 author notes that this is probably the first time that caoutchouc has been shown 

 to occur in any member belonging to the Myrtacejie. The small percentage 

 obtained, however, makes it at i)resent of scientific value only. 



The rubber industry of Mexico, P. Olsson-Seffer (Trop. Life, 6 {1910), 

 No. 3, pp. 50^2). — The author discusses the present status of the rubber indus- 

 try in Mexico and gives as a conservative estimate of the possible production 

 of rubber in that country between the years 1912 and 1915 a total of 18,000 tons 

 per annum from all sources, including wild and planted Castilla, Plnmeria, 

 Guayule, Pedilanthus, and Jntrophas, as ^^■ell as some minor rubber producers. 



DISEASES OF PLANTS. 



Plant diseases for the year 1909 worthy of special notice, K. Stormeb 

 (Lundw. Wehnschr. Bachsen, 12 {1910), Nos. 2, pp. 10-12; 3, pp. 19-21; J,, pp. 

 27-29). — Special mention is made of the grain fly ravages, oat root disease, grain 

 mites, loose snuit of grains, and leaf roll disease of the i)otato. Four methods 

 of treating the grain for prevention of loose smut were tried, namely, copper 

 sulphate, formalin, warm water, and liot air, but only tlie warm-water method 

 gave favorable results. 



In the copper sulphate treatment, three solutions of different strengths were 

 used, 1, 0.5, and 0.1 per cent, respectively. The grain in each case remained for 

 16 hours in the solution, which in one set of experiments was at a temperature 

 of 15° C. and in another at 25°. The results in all cases were unsatisfactory, 

 for. when the smut was materially decreased a marked injury to the germinat- 

 ing power of the grain followed. 



In the formalin treatment, the seeds were immersed in a 0.1 per cent solution 

 of formalin for 10 minutes with practically no effect on the smut. 



In the warm-water method, seed that had been soaked for G hours in water 

 at a temperature of from 20 to 25°, and seed that had not been soaked, was 

 immersed for 10 minutes in hot water, at a temperature for each experiment of 

 50, 53, and 56°, respectively. Only the soaked seed showed favorable results 

 in controlling the smut. In the case of barley, the smut was entirely destroyed, 

 but the germinating power was injured, the injury increasing with the degree 

 of heat used. With the summer wheat the effect on the smut was not so 

 marked, but the treatment was still of decided value. 



In the hot-air treatment, the following experiments were made: (1) Dry 

 grain heated for 45 minutes in hot air at a temperature of from 80 to 100°, 

 with no appreciable effect on the smut; (2) damp grain heated in air, first at a 

 temperature of from 50 to 60° for 60 minutes, and then raised to from 80 to 100° 



