AGRICULTURAL BOTANY. 431 



Chemical effects of radiant energy in plant processes, H. A. Spoehr {Car- 

 negie Itist. Washington Year Book, 11 (1912), pp. GS-65). — In continuation of 

 previous studies (E. S. R., 27, p. 521), the author reports on the effect of ultra- 

 violet light on the decomposition of carbon dioxid, etc. 



Contrary to the statement of Usher and Priestley (E. S. R., 25. p. 634), 

 carbon dioxid was not reduced to formaldehyde under the action of ultraviolet 

 light. It was found, however, that formaldehyde was formed when a solution 

 of potassium carbonate containing colloidal platinum and through which carbon 

 dioxid was allowed to pass was exposed to ultraviolet light. 



A number of plant acids were under observation, having been exposed to sun- 

 light for a year. The products formed by this long insolation are being investi- 

 gated. It has been found that acetic, glycolic, propionic, malic, tartaric, and 

 citric acids are decomposed in the light with the liberation of considerable 

 quantities of carbon dioxid. Formaldehyde is also formed, and, in the case of 

 the higher hydroxyacids, nonvolatile substances are produced which reduce 

 Fehling's solution. It was found in general that the acids were decomposed 

 much more easily in the the form of a salt than as the free acid. Formic acid 

 was not found to yield any reduction product. 



Influence of colloids on niicrobiolog'ical processes, N. L. Sohngen {Centhl. 

 Bakt. [etc.], 2. AM., 38 (1918), No. 21-25, pp. 621-647, figs. 4).— From several 

 series of studies the author concludes that adsorption phenomena are of con- 

 siderable significance in microbiological processes. Colloidal silicic oxid in the 

 Beijerinck culture medium promoted in marked degree the fixation of nitrogen 

 by Azotobacter, as did also raw humus and colloidal oxids of iron and alumi- 

 num. Alkali salts of humus acids hinder alcoholic fermentation, which, how- 

 ever, is favored by the presence of turf, filter paper, and garden soil. Oxidation 

 of petroleum by bacteria is considerably increased by the addition of colloidal 

 oxids of iron and silica. 



The behavior of micro-org'anisms in brines, G. J. Peirce (Carnegie Inst. 

 Washington Year Book, 11 {1912), pp. 52, 53). — The author has been observing 

 for three years the micro-organisms occurring in brines of salt works along the 

 shores of San Francisco Bay. The flora was found to vary with the concen- 

 tration of the brine, but although the brines were rich in organic matter it was 

 Impossible to secure an organic analysis. Many of the brine organisms were 

 found to be more or less completely saprophytic, but their relations to the 

 organic constituents of the brines could not be determined. 



Alterations in woody tissues and bacterial action in Salton water, M. A. 

 Brannon {Carnegie Inst. Washington Year Book, 11 {1912), pp. 51, 52). — A 

 study was made of stems of mesquite {Prosopis juliflora) and creosote bush 

 {Covillca tridentata), together with the water occurring in Salton Sea, to 

 determine the cause of certain changes that have been observed. 



Chemical analyses of the water did not reveal >4-uy free chemical that could 

 injure the plants, but it became evident that the changes were due to bacterial 

 action. Later it was proved that both the reduction of the sulphates and the 

 hydrolysis were due to the action of different groups of bacteria. The agents 

 that hydrolyzed the cell walls were formed by bacteria belonging to the Amylo- 

 bacter group. 



The effects of soluble humates on nitrogen fixation and plant growth, 

 W. B. BoTTOMLEY {Oard. Chron., 3. ser., 54 {1913), No. 14OO, pp. 295, 296, figs. 

 S). — In a lecture delivered before the Horticultural Club the author described 

 pot experiments which seemed to demonstrate that when sterilized peat, satur- 

 ated with active cultures of nitrogen-fixing organisms, is used to inoculate 

 ordinary soil, nitrogen fixation takes place much more rapidly than where liquid 

 cultures of the organisms are added directly to the soil. 



