AGRICULTURAL CHEMISTRY — ^AGROTECHNY. 411 



" Many of the products of enzymic action are excellent sources of carbon 

 and nitrogen for bacteria. The ammonia produced by the fungus from protein 

 material may, in the form of a salt, be directly assimilated by some plants. The 

 living organism hydrolyzes a small amount of cellulose in cellulose agar, but 

 the presence of cellulase could not be demonstrated in an enzym powder. 

 Neither lactase nor zymase were present in a powder from the growth in 

 lactose and glucose solutions respectively. Tannase was irroduced by the fungus 

 when grown In a tannin solution. The fungus showed no nitrogen-fixing power 

 in nutrient solutions containing either a carbohydrate (dextrose or mannite) 

 Of nitrogenous substance (peptone or ammonium sulphate) or both together." 



The soluble polysaccharids of lower fungi. — I, Mycodextran, a new poly- 

 saccharid in Penicillium expansum, A. W. Dox and R. E. Neidig {Jour. Biol. 

 Chem., 18 (1914), No. 2, pp- 167-175). — " This paper presents a study of a soluble 

 polysaccharid isolated from the apple fungus, P. expansum, which has hereto- 

 fore not been recognized in fungi nor observed in any of the higher plants." 

 The organism was selected for study on account of its great importance to 

 the apple industry. The indications were that the fungus also contains man- 

 nitol, peptone, glucose, inorganic salts, amino acids, pentosans, hemicelluloses. 

 and a chitin-like substance which on hydrolysis yields gliicosamin. 



The soluble polysaccharids of lower fungi. — II, Mycogalactan, a new poly- 

 saccharid in Asperigillus niger, A. W. Dox and II. E. Neidig {Jour. Biol. Chem., 

 19 (1914), No. 2; pp. 235-237). — ^A polysaccharid was obtained from a not quite 

 mature culture of A. niger. It was found to be a galactan and the name 

 mycogalactan is proposed. Mycogalactan like mycodextran (see above) appears 

 to be a reserve carbohydrate and is used by the fungus as a food supply as 

 soon as the sucrose of the medium is exhausted. 



Selective adsorption, E. G. Parkee {Jour. Indus, and Engin. Chem., 6 {1914), 

 No. 10, pp. 831-835, figs. 2). — " Soils not only have the power of absorbing dis- 

 solved salts from solution, but also adsorbing one ion at a greater rate than 

 the other, or of selectively adsorbing to an extent easily determined quantita- 

 tively. The nature of the surface of the constituents of a soil is such that the 

 cation is adsorbed at a much greater rate than the anion. 



"The presence of bases of the soil (Ca, Mg, etc.) in solution, after contact 

 of certain salt solutions with a soil, is not due to a direct chemical reaction 

 of the salt in solution with the silicates of the soil, but to a secondary reaction 

 of free acid resulting from the selective adsorption of the cation with the 

 mineral constituents of the soil. In general, the smaller the soil particles the 

 greater the selective adsorption of the cation. The selective adsorption of the 

 cation from a solution of an electrolyte by a soil increases with the concentra- 

 tion up to a certain point, and then remains practically constant, the surface 

 of the soil particles having taken up all that it is able at this point. At very 

 low concentrations the adsorption of the cation is practically complete. The 

 presence of other substances may or may not affect the selective adsorption by 

 a soil." 



The determination of ammonia in soils, R. S. Potter and R. S. Snydes 

 {Iowa Sta. Research Bui. 17 {1914), PP- 3-19, fig. 1). — These experiments were 

 conducted with a view of supplying a reliable method for the estimation of 

 the ammonia in soils. It is claimed that the method should meet the following 

 requirements : " Closely agreeing duplicate results should be given and the 

 same result obtained whether the reagent or reagents act, within reasonable 

 limits, for a longer or shorter period. . . . Upon the addition of a known 

 amount of ammonia, the method must give this added amount plus that pre- 

 viously found in the soil. . . . For use in a soils laboratory, the method should 



