No. 3, October, 1921] PHYSIOLOGY 265 



Rend. Soc. Phys. et Hist. Nat. Geneve 37: 74-79. 1920. — Investigating the relation of the 

 surface tension of a medium containing an enzyme to its activity, the author studied the 

 activity of tyrosinase in the presence of increasing concentrations of monovalent alcohols. 

 It was found that whatever alcohol was used, solutions of equal surface tensions produced 

 comparable results, the maximum stimiilation occurring at surface tension 70, and the post- 

 optimum decline becoming more gradual with increase in the length of the carbon chain. 

 Comparing the effect of alcohol with that of ether, chloroform, and acetone, the author con- 

 cludes that the hydroxyl group has a weak inhibitory effect on tyrosinase. The activity of 

 tyrosinase in the presence of alcohol is then the resultant of the stimulating effect induced by 

 lowering the surface tension, of the depressing effect of the hydroxyl group, and of the retard- 

 ing influence arising from the displacement of the enzyme by the alcohol at the surface of 

 the two phases. — Charles Drechsler. 



1632. Greig-Smith, R. Ropiness in wattle bark infusions. Proc. Linn. Soc. New South 

 Wales 45: 52-89. PL 9. 1920. — Ropiness is often encountered in tanning liquors and there 

 may be many causative organisms. This study was made on wattle bark infusions only, 

 but the results are considered applicable to tanning liquors. Two closely allied bacteria, 

 designated A and B, were isolated. They caused mucinous fermentation of bark infusions and 

 of synthetic media containing sugar. The chemistry of the reactions and products is dis- 

 cussed. Information obtained from tanners on the occurrence of ropiness in other than wattle 

 bark liquors is appended. — Eloise Gerry. 



1633. H^RissEY, H. Sur Thydrolyse du methyl-d-mannoside a par les ferments solubles. 

 [The hydrolysis of methyl-d-mannoside a by soluble ferments.] Compt. Rend. Acad. Sci. 

 Paris 172: 766-7G8. 1921. — Germinating seeds of lucerne are shown to contain d-mannosi- 

 dase. — C. H. Farr. 



1634. Mueller, Edward. The chemistry of enzyme actions. [Rev. of: Falk, K. 

 George. The chemistry of enzyme action. 136 p. Chemical Catalogue Company: New 

 York, 1921.] Amer. Jour. Public Health 11: 546. 1921. 



1635. Northrop, John H. The influence of the substrate concentration on the rate of 

 hydrolysis of proteins by pepsin. Jour. Gen. Physiol. 2 : 595-611. 1920. — It is pointed out that 

 the apparent exceptions to the law of mass action found in enzyme reactions may be found in 

 catalytic reactions in strictly homogeneous solutions. — These deviations in the rate of reaction 

 from the law of mass action may be explained by the hypothesis that the active mass of the 

 reacting substances is not directly proportional to the total concentration of substance 

 taken. — In support of this suggestion it is shown that for any given concentration of pepsin 

 the relative rate of digestion of concentrated and of dilute protein solutions is always the same. 

 If the rate of digestion depended on the saturation of the surface of the enzyme by substrate 

 the relative rate of digestion of concentrated protein solutions should increase more rapidly 

 with the concentration of enzyme than that of dilute solutions. This was found not to be 

 true, even when the enzyme could not be considered saturated in the dilute protein solutions. — 

 The rate of digestion and the conductivity of egg albumin solutions of different concentration 

 were found to be approximately proportional at the same Ph. This agrees with the hypothe- 

 sis first expressed by Pauli that the ionized protein is largely or entirely the form which is 

 attacked by the enzyme. — The rate of digestion is diminished by a very large increase in the 

 viscosity of the protein solution. This effect is probably a mechanical one due to the retarda- 

 tion of the diffusion of the enzyme. — Author's summary, 



1636. ScHMiTZ, Henry. Enzyme action in Echinodontium tinctorium Ellis and Everhart. 

 Jour. Gen. Physiol. 2: 613-616. 1920.— Mats of the tissue of Echinodontium ti)ictorium, a 

 destructive wood-destroying fungus, which had grown for 3 months in pure culture on sliced 

 carrots, were dried and powdered. Tests showed the presence of the following enzymes: 

 Esterase, maltase, lactase, sucrase, raflBnase, diastase, inulase, cellulase, hemicellulase, 



