316 EXPERIMENT STATION RECOED. 



Denudation of the steppe, A. Ivchknko (Ezhcyh. Ghcol. Min. Rossil, 1005, 

 PI). :il(')-i'iO ; I'.tUi), ])]>. 135-197 ; ahs. in Z/inr. Oimitn. Agron. [Russ. Jour. Expt. 

 JaukIiv. I, (S { 1907), No. 5, p. 550). — Contains among other things a very detailed 

 classification of alkali lands. 



Humus, It. McMuRTRiE iAinvr. Fert., ,-AS (1908), Xo. .',, pp. 5-//).— This is a 

 summary of information i-egarding the composition and functions of humus in 

 the soil. 



On changes of availability of nitrogen in soils, II, O. Loew and K. Aso 

 (Bui. Col. Agr., Tokyo Imp. Univ., 7 (1908), No. 5, pp. 567-574; abs. in Jour. 

 Chem. Soc. [London], 9 J, {1908), No. 5-',9, II, p. 621).— In an earlier article 

 on this subject (E. S. R., 19, p. 119) attention was called to "the existence 

 of bacteriolytic enzyms which probably play a role in the soils when the 

 nitrogen of bacteria is rendered available for the roots." 



This article reports culture experiments with Bacillus pyocyaneus, B. my- 

 coides, B. megatherium, B. suhtilis, B. fluorescens liquefacicns, and Proteus 

 vulgaris to determine whether these common soil bacteria produce bacteriolytic 

 enzyms. The results showed that the organisms under suitable conditions 

 produce bacteriolytic enzyms which gradually render new bacterial growth 

 difficult. " Since this may happen also in the soil, some explanation can be 

 furnished for the fact that bacterial life does not increase infinitely in organic- 

 ally manured soils." Other investigations bearing on this subject are briefly 

 reviewed. 



The enrichment of soil in nitrogen by bacteria and its significance for 

 plant nutrition, J. Stoklasa (Deut. Lundw. Presse, 35 (1908), Nos. 25, pp. 27//, 

 275; 26, pp. 286, 287; 27, pp. 297, 2.98).— This is a review of an article by Koch 

 and others (E. S. R., 20, p. 17), with a brief account of the author's recent 

 experiments with different organisms on oats, beets, and potatoes, the results 

 of which confirm his former conclusions. In soils inoculated with Azotobacter 

 chroococeum, adequately supplied with mannite or grape sugar and lime the 

 number of organisms was increased and both the yield and quality of the crops 

 were imi)roved. 



The biology of root tubercle bacteria of leguminous plants in the light of 

 recent investigation, F. Fuhkmann {Mitt. Nat uric. Ver. Steiermark, 1907, 

 pp. 3 ',-.36; abs. Centbl. Bakt. [etc.], 2. Abt., 20 {1908), No. 18-20, p. 618).— 

 The article briefly reviews the more important contributions to this subject. 

 It is stated that the fixation of atmospheric nitrogen by the root-tubercle 

 organisms begins when the bacteroids have reached a stage when they are 

 colored brown-red by addition of tincture of iodin. This occurs only when the 

 organisms are feeding almost exclusively upon carbohydrates and the available 

 nitrogen compounds have been almost completely exhausted. The question 

 of whether the process of assimilation is the result of symbiosis or parasitism 

 is also discussed. 



Experiments on the accumulation of green manure nitrogen in light 

 sandy soils, C. von Seelhorst {Mitt. Deut. Landw. Gesell., 23 {1908), No. 10, 

 pp. 83-89). — The results here reported confirm those of earlier experiments 

 (E. S. R., IS, p. 538) in showing as a rule a decided decline in soil nitrogen 

 from green manured soil as a result of growth of crops and loss in di-ainage. 



On observation of the continuous growth of peas on the same soil, S. 

 Suzuki {Bui. Col. Agr., Tokyo Imp. Univ., 7 {1908), No. 5, pp. 575-577).— The 

 results of four years' continuous culture of peas grown in pots on humus loam 

 soil unfertilized and fertilized in various ways are reported. These show that 

 no trace of soil " weariness " or " sickness " appeared when the soil was liberally 

 fertilized. The author therefore is inclined to accept the view that soil sickness 

 may in some cases be due simply to deficiency of available plant food. 



