718 EXPERIMENT STATION RECOED. 



or CS2, as previously used, could materially effect nitrate accumulation since 

 practical applications rarely ever exceed approximately 0.1 cc. per 100 gm. 

 soil." 



A short bibliography of the subject is given. 



The mechanism of denitrification, W. Hulme (Ahs. in Proc. Ghem. 80c. 

 London, 29 (1913), No. Jf20, pp. 307, 308; Jour. 80c. Ghem. Indus., 82 (1913), 

 No. 24, p. 1165). — "A series of experiments, conducted with a view to investi- 

 gate the mechanism of denitrification, showed that this reduction might be 

 divided into two parts, namely, (1) the bacterial reduction, and (2) the 

 enzymatic reduction. 



"The fermentation of similar media, one with and the other without potas- 

 sium nitrate, under anaerobic conditions, showed the gas evolution to consist of 

 nitrogen (98 per cent) and carbon dioxid from the nitrate-containing medium, 

 and of hydrogen (70 per cent) and carbon dioxid from the nitrate-free medium. 

 A medium containing only a very small percentage of nitrate evolved nitrogen 

 and carbon dioxid as long as nitrate and nitrite obtained in the solution, but 

 hydrogen and carbon dioxid appeared as soon as these had disappeared; thus 

 the chemical agent by which the organism reduces the nitrate is nascent 

 hydrogen. 



" The media were tested for enzym action by precipitation with alcohol, 

 drying, dissolving in water, and Chamberland filtration, measured quantities of 

 this solution being added to small quantities of a sterilized 1 per cent solution 

 of potassium nitrate, and the nitrite produced being measured. The results 

 showed a considerable reduction with the ' product ' obtained from the nitrate- 

 containing flasks, while that obtained from the nitrate-free flasks was devoid 

 of this reducing power. 



" These results were confirmed by a second series of experiments, in which 

 the fermentation took place aerobically. The enzym solutions in all cases 

 were not affected by boiling." 



Equations illustrating the mechanism of denitrification are presented, show- 

 ing the formation of carbon dioxid by the action of bacteria and of nitrogen by 

 the action of enzyms. 



The action of soil bacteria and their relation to condition of the soil and 

 plant growth, H. Fischer {Gartcnfiora, 63 {19U), No. 2, pp. 33-46).— This 

 article touches briefly on the different activities of soil bacteria in the decom- 

 position and transformation of fertilizing matter into available plant food, 

 taking up particularly the processes of nitrate and carbon dioxid formation, 

 nitrogen losses, nitrogen assimilation, and other related subjects. 



Nodule bacteria and preparations for soil inoculation, I. A. Makrinov 

 (ZJiur. Opytn. Agron. {Russ. Jour. Expt. Landic), I4 {1913), No. 6, pp. 341-367, 

 figs. 11). — Examinations and comparative tests were made of several commer- 

 cial preparations and of crushed nodules for the inoculation of leguminous 

 plants. The commercial preparations were found to be contaminated with other 

 organisms and contained comparatively limited numbers of Bacillus radicicola. 

 They were, however, as a rule more effective in promoting growth than the 

 water extracts of the crushed fresh nodules. 



Colloidal matter in clay and soils, P. Rohland {Internat. Mitt. BodenTc., 

 3 {1913), No. 6, pp. 487-493). — The nature, properties, and functions of colloids 

 in soils and their importance in agriculture are briefly discussed along the same 

 line as in previous articles (E. S. R., 22, p. 712; 29, p. 817). 



The solution and precipitation of iron in the formation of iron pan, 

 C. G. T. MoRisoN and D. B. Sothers {Jour. Agr. 8ci. [E7igl(ind], 6 {1914), 

 No. 1, pp. 84-96; aT)S. in Jour. 8oc. Ghem. Indus., 33 {1914), No. 4, p. 210).— 



