1919] AGRICULTURAL BOTAXY. G33 



the completion of the spore cycle of B. subtilis. The results are thought to be 

 capable of practical application in the preservation of food by canning and 

 other methods. 



[Viability of Pseudomonas radicicola under aerobic and partial anaerobic 

 conditions], F. O. Ockekblad {Michigan Sta. Rpt. 1918, pp. 255-26^). — On ac- 

 count of the practice of experiment stations and commercial firms of distribut- 

 ing cultures of nodule-forming bacteria in liquid media, the author conducted 

 a series of experiments with 12 strains of P. radicicola under various conditions 

 to determine their effect on the viability of the organisms. Liquid and solid 

 cultures were inoculated with a suspension of bacteria and incubated for two 

 weeks at temperatures of 20 to 23° C. The containers holding one-half of each 

 lot were plugged with cotton and the others with cork stoppers. 



Examinations of the organisms were made from time to time, and it was 

 found that the cultures in cork-stopped bottles died quite rapidly. The or- 

 ganisms living after 160 days averaged 0.21 per cent for the liquid and 3 per 

 cent for the solid cultures. The viability of the organisms in ash-sugar solu- 

 tion was much less than that on ash-sugar agar. On the ash-sugar agar under 

 cotton plugs the different strains died gradually, an average of 91.1 per cent 

 living after 20 days, 46.2 per cent after 100 days, and 12.5 per cent after 160 

 days. The thermal death point of different strains was determined to fall 

 between 59 and 61°. Four of the 12 organisms were found to stand a tempera- 

 ture of 60°, but none of them was able to grow after being exposed for 10 

 minutes at a temperature of 61°. 



The factors considered to cause a decrease in the number of living organisms 

 are partial anaerobic conditions, accumulation of metabolic and toxic products, 

 and plasmolysis caused by the concentration of the ash-sugar solution through 

 evaporation. In the case of the unsealed liquid cultures, it is believed that 

 the partial anaerobic condition in the medium was a factor in the decreased 

 number of living bacteria. With the sealed cultures of both media, the partial 

 anaerobic conditions, which tended to become wholly anaerobic, are considered 

 the principal cause of the dying off of the bacteria. 



Prussic acid in Burma beans, E. J. Wakth and K. K. Gyi (Agr. Research 

 Inst. Pusa Bui. 79 (WIS), pp. 11).— The results of studies carried out to date 

 with local (Burmese) varieties of Phaseolus lunatus as to their content of 

 hydrocyanic acid are said to show that, while the amount present in the cul- 

 tures varies considerably with soil and climatic conditions, cultures giving low 

 percentages in one locality give low figures under all conditions tested. Hydro- 

 cyanic acid content thus appears to be an inherited character in pure single 

 plant cultures. Differences in the color of seeds from a single culture do not 

 indicate corresponding probable differences in the hydrocyanic acid content 

 of the progeny. While the best cultures thus far found contain some of this 

 poison, the quantity now obtained is only half that contained in the original 

 sample of Madagascar bean which was regarded as safe and introduced into 

 the Province. 



A fern having- hydrocyanic acid, M. Mirande (Compt. Rend. Acad. 8ci. 

 [Paris], 167 (1918), No. 19, pp. 695, 696).— The author has found that Cystopteris 

 alpina {€'. fragilis alpina) contains hydrocyanic acid in the green parts (fronds). 

 The process of separating the acid is briefly described. 



Notes on dune vegetation at San Francisco, Cal., F. Ramaley {Plant 

 World, 21 {1918), No. 8, pp. 191-201, figs. ^).— A description is given of the 

 forms of vegetation on the sand dunes of Golden Gate Park as noted on exposed 

 points, protected areas, and low places. Plant associations are noted. A 

 systematic list is given, containing 40 native and 8 introduced species. 



