RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



International catalogue of scientific literature. D — Chemistry {Iriternat. 

 Cat. Sci. Lit., 7 (1910), pp. YIII-\-llS~).—T\\e literature luclexed comprises 

 material received between December, 1907, and December, 1908, and continues 

 previous work (E. S. R., 21, p. 112). 



Methods and results of micro-chemistry, A. Prenant {Jour. Anat. et 

 Physiol. [Paris], 40 {1910), No. //, pp. S'/S-J/O^)- — The evolution of the science 

 of micro-chemistry is considered, with particular reference to the reactions 

 employed in vegetable and animal histology and physiological chemistry. 



Methods for producing colloidal solutions of inorganic substances, T. 

 SvEDBERG {Die Methoden ziir Herstellung Kolloider Losunyen Aiwrganischer 

 Stoffe. Dresden, 1909, pp. XII+507, pis. S, flgs. 60).— A clear description of 

 the condensation and dispersion methods for producing colloidal solutions of 

 inorganic bodies. 



Analysis and determination of the constitution of organic compounds, 

 H. Meyer {Analyse und Konstitutionsermittclung Organischer Vcrbindungeii. 

 Berlin, 1909, 2. ed., rev. and enl., pp. XXXII+lOnS, figs. 235).— This is the 

 second edition of this work, which has been entirely rewritten and brought 

 up to date. 



The usefulness of curves in the interpretation of microbial and biochemical 

 processes, O. Rahn {Miehigan 8ta. Tech. Bui. 5, pp. 29, figs. 18). — A discus- 

 sion of the possibility and value of interpreting microbial or biological processes 

 mathematically. 



" If a curve of a biochemical process is platted, taking us abscissa the time 

 elapsed and as ordinate the total amounts of compounds produced, the shape 

 of this curve will in many instances indicate the nature of the change taking 

 place. In a purely chemical or enzymic change, the active mass does not increase, 

 and therefore the rapidity of the process measured by the angle of elevation of 

 the curve does not increase. . . . The curve changes with the time, becom- 

 ing gradually parallel to the base line. If we are dealing with changes caused 

 by micro-organisms, the active mass increases as long as micro-organisms in- 

 crease, and consequently the rate of the process or the angle of elevation will 

 rise as long as the increase continues. This elevation of the curve is charac- 

 teristic for compounds produced by any multiplying organism. From the time 

 the increase ceases, we are dealing with a purely enzymic curve. 



" The exact platting of the curve allows us to make fairly accurate statements 

 about the multiplication and the duration of the increase of bacteria, even if 

 they can not be counted by our present methods. The point of inflection of a 

 curve shows the moment when the organisms producing the substance under 

 study reach their maximum number and can be studied with greatest con- 

 venience. 



" In some instances, the point of inflection Is changed to a straight line, indi- 

 cating a strain of bacteria very resistant to their own products; this seems to 

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