SOILS FERTILIZERS. 427 



versial in character and is devoted mainly to an answer to statements by H. 

 Fisclier ( E. S. 11.. 21. i*. 41()). 



Magnesia-gypsum disks and magnesia disks with organic matter as con- 

 venient solid substrata for the culture of nitrifying organisms, I. A. Mak- 

 RiNOV {Centbl. Bakt. [etc.], 2. AM., 2Jf (1909), No. 13-15, pp. -',1.5-423, pis. 2).— 

 The investigations here reported have been noted from another source (E. S. R., 

 22, p. ?,18). 



Studies in soil bacteriology, III. Concerning methods for determination 

 of nitrifying and ammonifying powers, F. L. Stevens, W. A. Withers, et al. 

 (Ccnthl. Bakt. [etc.], 2. Abt., 25 {1909), No. l-'t, pp. 6>,-80, flg.'i. //).— This paper 

 is the third of a series on this subject (E. S. R., 21, p. 619), and deals mainly 

 with the methods used by the authors in determining the nitrifying and 

 ammonifying powers of soils. 



Nitrogen assimilating micro-organisms, Apelt (Ztschr. Natww., 80 (1908), 

 No. 3-J,, pp. 300-302; ahs. in CciitU. Bakt. [etc.], 2. Abt., 25 {1909), No. 10-13, 

 p. 321). — Brief references ai-e made to the investigations of ,T. Kiihn, Krieger, 

 Henry, Berthelot, Winogradski, and Beijerinck. 



Azotobacter chroococcum, its physiological properties and its activity in 

 soil, A. Krainskii iZliur. Opuittt. Ayron. (Rii.s.s. Join: K.ipt. Lanilw.). 9 {1908), 

 No. 6, pp. 689-749, fig.^. 8; abs. in Cliem. Abs., 3 (1909), No. 24. p. 2991).— It was 

 found in the investigations here reported that A. chroococcum varies widely 

 with the age and nature of the nutrient substratum used in pure cultures. A 

 marked characteristic is the development of a black pigment in the culture 

 media in from 3 to 7 days. Levulose, inulin, and mannite were found to be 

 the best sources of carbon for this organism. Arabinose and galactose were 

 but slightly utilized, a fact which casts doubt upon the conclusion of Heiuze 

 that the organism feeds upon pectin compounds of the soil. 



Respiration (evolution of CO2) and nitrogen fixation were studied in a 

 variety of media. The author concludes that nitrogen fixation is practically 

 complete in 6 weeks. The best results were obtained in soils with small 

 amounts of moisture, from one-half to three-fourths of the optimum content. 

 The organism is apparently highly aerobic and does not develop well in a soil 

 from which the air is excluded to any large extent by moisture. Sodium 

 carbonate was more favorable to nitrogen assimilation than calcium carbonate, 

 indicating that the beneficial action of lime is due simply to its alkalinity. 

 The addition of carbon bisulphid increased both the amount and the intensity 

 of the nitrogen fixation. This is attributed, contrary to Heinze's conclusion, 

 not to direct action on the organism but to solution of the fats and waxes of 

 the soil, thus increasing its porosity. 



Fixation of free atmospheric nitrogen by Azotobacter in pure culture. — 

 Distribution of this bacterium, M. W. Beijerinck {K. Akad. Wetensch. 

 Am.sterdam, Proc. Beet. ScL, 11 (1908-9), pt. 1, pp. 67-7//).— This article deals 

 especially with the relation between Azotobacter and salts of organic acids, 

 more particularly calcium malate. It is shown that considerable amounts of 

 nitrogen are fixed by Azotobacter alone in pure cultures in which the carbon 

 supply is derived from malates or similar organic salts, but that the fixation 

 is greater when other organisms are associated with the Azotobacter. The use 

 and value of nutrient media containing calcium malate instead of sugar for 

 the study of the distribution of Azotobacter in the soil are explained. By 

 means of the method a distinct relation was shown to exist between 

 Papilionacefe growing on the soil and the distribution of Azotobacter. 



Bacteriological examination of nitro-bacterine, L. Grandeau (Jour. Agr. 

 Prat., n. ser., 18 (1909), No. 45, pp. 625, 626). — Bacteriological examinations 

 and pot tests with lupines made at the Stockholm experiment station showed 



