AGRICULTURAL BOTANY. 29 



monocalcium phosphate plus hydrochloric acid. The smaller the amount of 

 phosphoric acid present for the development of the Azotobacter, the less eco- 

 nomical was the consumption of the source of energy in the nitrogen fixation. 



Ill the experiments on ammonia cleavage in peptone solutions, it wfis found 

 that the intensity of such cleavage depended not only on the bacterial flora of 

 those soils, but more so on their chemical composition and especially on the 

 presence of phosphoric acid. In Remy's method of investigating decomposition 

 processes it was found necessary to add to the peptone solution an easily assim- 

 ilable phosphoric acid compound (as dipotassium phosphate) for the use of the 

 bacteria. The addition of easily assimilable organic matter (as carbohydrates) 

 to the peptone solution inoculated with earth decreases the amount of ammonia 

 formed, while the addition of small amounts of some humic acid salt increases 

 it. A strong aeration decreased, at least in many cases, the quantity of ammo- 

 nia split off from the peptone solution which had been inoculated with earth. 



A method for the determination of the cellulose-fermenting ability of 

 soil organisms, H. R. Christensen {Centhl. Bakt. [etc.], 2. AM., 27 (1010), 

 No. 11-21, pp. JfJt9-Ji51). — The author describes in detail a method for determin- 

 ing the disintegrating ability of cellulose-fermenting organisms of various soils. 

 This consists in placing narrow strips of ash-free filter paper in a 300 cc. Erleu- 

 meyer flask with 50 gm. of the well pulverized and thoroughly moistened soil, 

 and observing the rate of disintegration of the filter paper. 



Investig'ations on the occurrence of Azotobacter in moor soils, H. von 

 Feilitzen {FilhUng's Landw. Ztg., 59 {1910), No. 1.',, r>p. //8.9-//92).— Observa- 

 tions on samples of soils from the Flahult experimental farm varying in lime 

 content and acidity and in previous treatment indicate that Azotobacter occurs 

 in very small numbers even in the best of the moor soils which have been under 

 cultivation for a long time. No direct relation between lime content and de- 

 velopment of Azotobacter could be established. Neither was any positive 

 relation between such development and the reaction of the soil brought out by 

 these observations. 



On the mineral needs of Azotobacter, H. Kaserer {Ber. Deut. Bot. Gesell., 

 2S {1910), No. 6, pp. 20S-212). — It is claimed as a result of experiments that all 

 bacteria need iron and aluminum for their proper growth. 



This need is supplied by the usual organic media, and, therefore, is not ob- 

 served until albuminoid-free media in the absence of organic acids are used, 

 because the organic acids prevent the precipitation of the iron and aluminum 

 compounds which exist everywhere, especially in glass. Experiments with 

 different strains of Azotobacter show that this need of iron and aluminum 

 varies very materially with the different strains. 



Researches on the assimilation of free nitrog'en uy green plants, Eva Mameli 

 and G. Pollacci {Atti R. Accad. Lincei, Rend. CI. Sci. Fis., Mat. e Nat., 5, ser., 

 19 {1910), I, No. 8, pp. 501-50-',).— A preliminary statement is given of experi- 

 ments on the assimilation of atmospheric nitrogen by some of the higher plants, 

 in which it is claimed that certain plants {Azolla caroUniana, Lemna major, 

 L. minor, Salvinia auriculata, Anthiirium sp., Tradescantia sp., and Salvia sp.) 

 when grown in air and media free from nitrogen compounds were able to grow 

 vigorously and to absorb definite quantities of nitrogen from the atmospliere. 

 Complete descriptions of the methods used and results obtained will be published 

 later. 



On the infection of serradella and other cultivated plants with several 

 species of bacteria, L. Hiltner {rUus. Landw. Ztg., 30 {1910). No. 38, pp. 319, 

 320).— The results are given of field experiments by various farmers on inocu- 

 lating serradella with nitragin and also with bacteria which were isolated from 

 the roots of serradella plants. It is claimed that beneficial results were ob- 



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