EXPERIMENT STATION RECORD. 



Vol. 40. Abstract Number. No. 3. 



RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



Chemical studies on physiology and pathology. — I, Protein chemistry as 

 the basis of the life process, E. Herzfeld and R. Klinger {Biochem. Ztschr., 

 88 (1917), pp. J,2-61; abs. in Physiol. Abs., 2 (1918), No. 11, pp. 660, 661; Chcm. 

 Abs., 12 (191S), No. 8, p. 809).— The theory is advanced that the protein mole- 

 cule consists of a solid nucleus surrounded by layers of higher and lower 

 cleavage products, each cleavage product being the best solvent of the next 

 higher product in the series. The application of this theory to cell metabolism, 

 to certain diseases, and to glandular secretion is discussed. 



On the amino-acid content of nutrient media, I. W. Hall et al. | Brit. Med. 

 Jour., No. 3015 (1918), pp. 398-401).— Studies are reported of the amino-acid 

 content of ordinary and special media, the percentage of amino acids necessary 

 for bacterial growths, and the influence of vitamins on the amino-acid content 

 of media. 



Ordinary media were found to vary widely in their amino-acid content. The 

 bacterial growth in media varying in amino-acid content showed that a content 

 represented by a formaldehyde figure of 40 is the optimum for growth. An 

 examination of the effect of different vitamins on the growth of organisms 

 showed that the source of the vitamins was apparently immaterial, with the 

 exception of the soy bean, which led to a much more marked growth than the 

 other vitamins. 



In conclusion the authors propose the general adoption of a uniform amino- 

 acid standard content for nutrient media. 



The inversion of cane sugar by colloidal silica, Axbkbt and Alexandre 

 Maby (Compt Rend. Acad. So*. [Paris], 167 (1918), No. 18, pp. 6U-646).— Three 

 series of experiments are reported, the first with dialyzed hydrosols and the 

 other two with nondialyzed hydrosols of colloidal silica, from which the follow- 

 ing conclusions are drawn : 



Colloidal silica, as well as mineral acids, acetic acid, invertase, and the 

 hydrosols of palladium, gold, and platinum, invert cane sugar in an appre- 

 ciable manner. Its inverting power is a function of its state of dispersion. 

 It is inactivated by the physico-chemical circumstances which destroy the dis- 

 persal phase of its pseudo-solutions. In certain conditions of physical insta- 

 bility its activity increases with the temperature up to a variable optimum 

 (below 100° C.), and then decreases to complete inactivation. Its conditions 

 of activity are thus comparable in certain respects to those of colloidal metals 



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