22 EXPERIMENT STATION l^KCORl). 



"Bacterial life and activity soein to i-isc .-md tall with iiiorc or l(>ss ri'.uu- 

 larity. These periods of maximum and minhmnii activity are to a certain 

 extent independent of moisture and temperature and are possibly due to tlio 

 l)rt'sence of bacterial by-])roducts." 



The assimilation of atmospheric nitrogen by soil micro-organisms, F. 

 Stkanak {Ztsclir. ZuckcriinlK.s. liohmcn, 33 {190!)), Xo. 10, pj). oDD-Gl.'/ ; ahs. 

 ill Chcm. Aim., 3 {1009), No. 18, pp. 2192, 2193; Jour. Chcm. Soc. [London]. 9t; 

 (1909), iVo. 5G2, II, p. 692; Chcm. Zenthl., 1909, II, No. 8. pp. i;',7. ().',S; CUrni. 

 Ztg., 38 {1909), No. 9o, Rcpcrt., p. J,09 ; Ccnlhl. Unit, [etc.], 2, A hi., 23 {1909), 

 No. 10-13, pp. 320, 321). — The work of other investigators on this subject is 

 reviewed, and the author's own experiments with Azotohacter chroococcum are 

 described with a full account of methods of isolating the organism. 



A comparison of various sugars as carl)ohydriite food for the organism 

 showed that arabinose was the most efficient source of such food and indicates 

 that the pentosans of the soil are of great importance in the assimilation of 

 nitrogen by soil bacteria. The average consumption of carbohydrates per gram 

 of nitrogen assimilated was 1G5 gm. in case of glucose. In the presence of 

 lutrates Azotobacter derived its supply of nitrogen from this source and not 

 from atmospheric nitrogen. The organism reduced nitrate nitrogen to ammonia. 



In soil tests inoculation with Azotobacter caused a pronounced increase in 

 the yield of beets, grain, and potatoes. In a pot experiment inoculation with 

 pui'e culture of Azotobacter gave less increase in yield than was obtained with 

 inoculating material preparetl as follows: Inoculate 5 kg. of soil containing 2.")0 

 gm. of glucose with 500 cc. of a glucose culture of Azotobacter and allow to 

 incubate for 3 months at 24° C. 



Azotobacter was found to be widely distributed in cultivated fields, meadow 

 land, and forest soils, but absent from many virgin soils and soils at consider- 

 able elevations. It was abundant, however, in virgin soils having a luxuriant 

 growth of blue and green alg.-e. 



Bacillus amylobacter and the regeneration of the power of assimilation 

 of free nitrogen, J. P]. Weiss {Jahrh. Natuno., 2} {1908-9), pp. 221-223).— 

 This is a brief review of the investigations of Bredemann on this subject (E. S. 

 R., 21, p. 717). 



On. the mechanism, of denitrification by indirectly denitrifying bacteria, 

 L. Grimbert and M. Bagros {Jour. Pharm. et Chim., 6. ser., 30 {1909), No. 1, 

 pp. 5-10; ab-'^. in Rev. G6n. ScL, 20 {1909), No. 20, pp. 832, 833).— A continua- 

 tion and completion of previous investigations is here reported. The influence 

 of different kinds of carbonaceous food on the fixation of nitrogen by Bacillus 

 coli was studied No denitrification occurred in nitrated peptone cultures when 

 either various carbonaceous substances or amid or amin compounds were added 

 separately, but when the two classes were combined there was innnediate and 

 active development. 



Bog toxins and their efEect upon soils, A. Dachnowski {Bot. Gaz., l/l 

 {1909), No. 5, pp. 389-li05, figs. 2). — Investigations are reported which indicfrte 

 that the sterility of many swamp and nuick soils is due to the presence of toxins 

 dependent mainly upon physical and chemical factors but also influenced by 

 excretion from roots and rhizomes of [ilants. The roots of wheat plants grown 

 in untreated bog water contained on their surface numerous colored bodies re- 

 sulting from the oxidizing action of the roots, but the general decay of the root 

 tips indicated that the oxidizing power was insufficient to decrease the injurious 

 effects of the bog toxins. Treating the bog water with an insoluble absorbent 

 agent invariably proved beneficial. The presence of small amounts of toxic sub- 

 stances accelerated growth. The capacity of soils for retaining the toxins was 

 found to be higher the greater the content of humus. 



