46 PHYSIOLOGY [BoT. Absts., Vol. X, 



attack trehalose, while B. paratyphosus, B. Schottmulleri, the animal para B sub-group, and 



B. enteritidis ferment trehalose with the production of acid and gas. A further differentiation 

 of B. Schottm ulleri strains from the animal para B group is accomplished by employing a serum 

 water medium containing 0.5 per cent trehalose and 1 per cent Andrade indicator. — Selman 

 A. Waksman. 



281. MiRANDE, Marcel. Sur les graines a autofermentation sulfhydrique de la famille 

 des Papilionacees. [Hydrogen sulphide autofermentation of seeds of the Papilionaceae.] 

 Compt. Rend. Acad. Sci. Paris 172: 1202-1204. 1921. — Seeds of certain legumes are found to 

 undergo auto-fermentation when placed in a little water, splitting off active HjS. More 

 than 9 species are named which produce much HaS, 9 are given which produce only a little, 

 and 5 which do not produce it at all. There is also a discussion of the fermentation capacity 

 in the flour of these legumes, in bread made in part from such flour, and in soup preparations. — 



C. H. Farr. 



282. Northrop, John H. The significance of the hydrogen ion concentration for the diges- 

 tion of proteins by pepsin. Jour. Gen. Physiol. 3: 211-227. 1920. — The writer suggests that 

 proteins are acted upon by pepsin only when they are in the ionized condition. Evidence 

 in support of this is given as follows: (1) Curves for the rate of digestion of the proteins, 

 oxyhemoglobin, egg albumin, and gelatin run parallel to the conductivities of the solutions 

 when these are both plotted against the Ph values. (2) The decrease in the rate of digestion 

 induced by an excess of HCl above the optimum is duplicated by the addition of an excess 

 of this same CI ion in equivalent concentrations when in combination with 6 different cations. 

 (3) Oxyhemoglobin, with its isoelectric point at about Ph 6.8, is more highly ionized at Ph 4.5 

 than are other proteins with isoelectric points at more nearly Ph 4.5, and it is also more ra- 

 pidly digested at this hydrogen ion concentration. — Otis F. Curtis. 



283. Pease, R. N., and H. S. Taylor. Promoter action in catalysis. Jour. Phys. Chem. 

 24: 240-265. 1920. — Promotor action is to be distinguished from activation ("by a substance 

 relatively inert catalytically, or by a small quantity of a relatively active substance") and 

 from co-activation ("of a number of catalysts each by the rest") in that it includes "all those 

 cases in which a mixture of two or more substances is capable of producing a greater catalytic 

 effect than can be accounted for on the supposition that each substance in the mixture acts 

 independently and in proportion to the amount present." Examples of each type are given 

 and these include actions of enzymes and co-enzymes as well as various technical catalytic 

 processes. — H. E. Pulling. 



284. Potter, M. C. The influence of electric potential upon the velocity of fermentation. 

 Proc. Univ. Durham Phil. Soc. 6: 16-21. 1915-1920. — In a previous paper the author showed 

 that a rise of potential amounting to as much as .3-.5 volt is produced by yeast growing in a 

 fermentable liquid. In order to determine the influence of the difference of potential on the 

 velocity of reaction, the author compared the rate of fermentation of glucose by yeast in a 

 flask carefully insulated, or raised to a definite potential, with that in a similar flask in which 

 the glucose was grounded. No difference in the rate of fermentation was observed. — J . S. 

 Cooler/. 



285. Willstatter, Richard. IV. tJber Peroxydase. [Concerning peroxidase.] Ann. 

 Chem. [Liebig] 422: 47-73. 1921. — The peroxidase value is the purpurogallin number of 5gr. 

 of plant tissue. This number designates the nimiber of mgr. of purpurogallin formed by the 

 reaction during 5 minutes between 1 mgr. enzyme-containing plant tissue, 5 gr. pyrogallol, 

 and 50 mgr. hydrogen peroxide, in a volume of 2 1. at 20°C. The peroxidase value of fresh 

 roots of horseradish varied from 800 to 1520. The use of toluol, or aspiration with oxygen, 

 during the extraction of the tissue greatly reduced the peroxidase value. Dialyzing for several 

 days this value increases, as is especially true of the soluble form of peroxidase. The insolu- 

 bility of the peroxidase suggests a chemical combination within the cell, but it is not made 

 soluble by either bariiun hydroxide or oxalic acid. The use of oxalic acid was found to permit 



