SOILS FERTILIZERS. 123 



548, pp. 287-289; Centbl. Bakt. [eic], 2. AU., 25 {1909), No. 5-9, pp. 270-272; 

 abs. in Chem. Zentbl., 1909, II, No. 9, p. 742). — The nitrogen-fixing power of 

 Pseudomonas alone and combined witli Azotobacter (both obtained from root 

 tubercles of Cycas) was studied in culture experiments and in pot tests with 

 barley, oats, parsnips, and hyacinths. The results as measured by the increase 

 of nitrogen in the culture solution and by the growth of the plants indicated 

 in the author's opinion a decided fixation of nitrogen by the combined cultures. 

 The fixation of nitrogen by soil bacteria, A. D. Hall {Nature [London], 81 

 {1909), No. 2073, p. 98). — Discussing the above experiments, the author main- 

 tains that the results of the experiments were not conclusive because there 

 were no tests of Azotobacter alone and no means of accurately measuring the 

 experimental error. 



Nitrog'en-fixing bacteria and nonleguminous plants, W. B. Bottomley and 

 A. D. Hall {Nature [London], 82 {1909), No. 2095, pp. 218, 219).— This is a 

 further discussion of the reliability of the conclusions drawn by Professor 

 Bottomley noted above. 



Important bacteria in Jamaica soils, S. F. Ashby {Bid. Dept. Agr. Jamaica, 

 n. ser., 1 {1909), No. 2, pp. 92-96, pi. 1). — Studies of the rate of nitrification 

 and nitrogen fixation in 3 different soils are reported, as well as tests of a cul- 

 ture prepared by Bottomley for increasing the assimilation of nitrogen by sugar 

 cane. This culture was found to contain Clostridia but not Azotobacter and 

 was without effect when used on sugar cane. 



The regeneration of the nitrogen-fixing power of bacteria, G. Bredemann 

 {Centbl. Bald, [etc.], 2. Abt., 23 {1909), No. 1-5, pp. 41-47).— A controversial 

 note replying to Pringsheim (E. S. R., 20,. p. 18). 



The identity of nitrogen-fixing Clostridia, H. Pringsheim {Centbl. Bakt. 

 [etc.], 2. Abt., 24 {1909), No. 18-22, pp. 488-496).— This is a controversial ar- 

 ticle replying to criticisms of the author's work by Bredemann (noted above). 

 The fertility of the soil, H. Putticmans (Ann. EscoUi Polytcch. Mo Paulo, 9 

 {1909). pp. 301-344, pi. 1, figs. 10). — This article reviews the present knowl- 

 edge and theories with regard to soil fertility, discussing the physical, chemical, 

 and micro-biological factors determining it. 

 A bibliography of 41 references is appended. 



Analyses of soils {Rev. Asoe. Rural Uruguay, 38 {1909), No. 8, pp. 586-589, 

 dgms. 2). — Physical and chemical analyses of several samples of soil from the 

 Campana model farm in Uruguay are reported with a description of the char- 

 acter of the soil at different depths. 



The natural regeneration of worn out cocoa soils, W. C. Jardine {Dept. Agr. 

 Trinidad, Bid. Agr. Inform., 1909, n. ser., No. 63, pp. 81-88).— The utilization of 

 the natural vegetation for restoring the fertility of such soils is discussed. 



The uncultivated soils in Denmark {Rev. Sei. [Paris], 47 {1909), II, No. 5, 

 pp. 142, 143).— This is a brief note on the activities of the Landes Society of 

 Denmark in the reclamation of swamp and other unproductive soils. 



On the earth temperature at Osaka, T. Okada {Tokyo Hug. But. Kizi [Proc. 

 Tdkyo Math. Pliys. Soc.], 2. ser., 4 {1908), No. 21, pp. 427-438; abs. in Beibl. 

 Ann. Pliys., 33 {1909), No. 14, p. SOO).— Hourly observations of temperature at 

 the surface, and at depths of 0.1, 0.3, and 0.0 meter during 1901 to 1906, and 

 monthly mean temperatures at the surface and at depths of 0.3, 1.2, 3, and 5 

 meters from 1895 to 1904, are reported. On the basis of these observations and 

 of determinations of the moisture content of the soil studies were made of the 

 diurnal and annual variation of the temperature of the soil, diurnal and annual 

 heat exchanges of the soil, and thermal conductivity of the soil. The specific heat 



20872— No. 2—10 3 



