118 PHYSIOLOGY [Bot. Absts., Vol. VI, 



species of plant. In general the greater the freezing-point depression of the cell sap the less 

 the amount of easily freezable water. The concentration of the cell sap of roots as measured 

 by the freezing-point method is decidedly influenced by the concentration of the soil solution 

 in which the plants are grown, but the concentration of the cell sap of the tops is not so mark- 

 edly affected. The amount of water which froze at —2.5° and — 4°C. in the tops of barley and 

 corn was not markedly influenced by varying the concentration of the nutrient solution added 

 to the soil when the water content of the soil was held constant. When grown in soil of high, 

 medium, and low water content the plants in the soil of high water content possessed more 

 easily freezable water. When the water content varied, but the concentration of the soil 

 was held constant, more water froze at — 2.5°C. in the leaves of plants grown in soils of low 

 water content. — -11'. ./. Robbins. 



MINERAL NUTRIENTS 



831. Hartwell, Burt L., and S. C. Damon. The value of sodium when potassium is 

 insufficient. Rhode Island Agric. Exp. Sta. Bull. 177. 29 p. 1919. 



832. Winslow, C.-E. A., and I. S. Falk. The effect of mineral salts upon the viability 

 of bacteria in water. [Abstract.] Absts. Bact. 3: 5. 1919. 



833. Aronovitch, B. On the soluble toxic substances of the colon-typhoid group. [Ab- 

 stract.] Absts. Bact. 4: 9. 1920. 



METABOLISM (GENERAL) 



834. Bridel, Marc. Sur la presence simultanee du gentianose et du saccharose dans les 

 especes du genre Gentiana. [Simultaneous occurrence of gentianose and saccharose in Gen- 

 tiana.] Compt. Rend. Soc. Biol. Paris 83: 24-25. 1920. — In addition to Gentiana lutea, where 

 these two sugars had already been reported, the author determined their presence in G. 

 asclepiodea, G. punctata, G. cruciata and G. purpurea. From September to November the 

 gentianose decreased while the saccharose increased in amount almost proportionally. It 

 is suggested that these are convertible one into the other under the action of the enzyme gen- 

 tiobiase. — E. A. Bessey. 



835. Bronfenbrenner, J., and M. J. Scheesinger. Carbohydrate fermentation by bac- 

 teria as influenced by the composition of the medium. [Abstract.] Absts. Bact. 3: 8. 1919. 



836. Cooledge, L. H., and R. W. Wyant. The sanitary quality of milk as judged by the 

 colorimetric hydrogen ion determination. [Abstract.] Absts. Bact. 4: 6. 1920. 



837. De Domini cis, A. Sul significato biologico delle sostanze tanniche. Variazionl del 

 contenuto in tannino nella corteccia di castagno secondo i mesi e le stagioni. [The biological 

 significance of the tannins. Monthly and seasonal variations in the tannin content of the bark 

 of the chestnut.] Staz. Sper. Agr. Ital. 52: 305-331. 1919. — In order to decide upon the ques- 

 tion as to whether the tannins are storage or secretory materials the author undertakes a 

 study of the variation in tannin content of the bark of Castanca trees aged 2-5 and 20 years. 

 The results are not readily summarized, but in general, the maximum content occurred at 

 some time between early autumn and late winter, while in July — and usually as early as May — 

 it was relatively low. — After a review of the chemical and physiological literature and a lengthy 

 discussion the following conclusions are drawn. According to their origin, constitution, and 

 physical and chemical properties the tannins should be considered in their main lines as 

 glucosidal compounds, products of the etherification of an aromatic oxyacid and a sugar, gen- 

 erally glucose. The acids are of the fundamental types of gallic acid (C 6 H2(OH) 3 COOH) and 

 protocatechuic acid (C 6 H3(OH) 2 COOH). The above-mentioned acids may be indirectly 

 derived from quercitol and inositol. These conclusions regarding the derivation of the tan- 

 nins and their glucosidal nature are upheld by their biogenetic, synthetic, and optical proper- 



