No. 3, July, 1921] PHYSIOLOGY 319 



94: 265-284. 1919. — Experiments on various species of plants with .05 and .01 per cent solu- 

 tions of ammonium-ferrosulphate showed that the roots possess considerable powers of oxi- 

 dizing the iron. It was found that the oxidizing ability is localized in the regions of the root 

 hairs and at the growing tips. Within the root tissues, the separation of iron takes place 

 in the central cylinder and especially in the wood bundles on the inner walls of the vessels 

 and in the adjoining hadrome parenchyma cells; also in the interior of the tissues of the root 

 tip. Considerable differences were found in the oxidizing ability of the different plants 

 tested, according to the extent of their root systems. The weakest in this respect was Sinapis 

 and the highest Phaseolus, with Triticimi, Cannabis, Lupinus, and Pisum ranging between, 

 in the order named. Trilicum, and to a certain extent Sinapis and Cannabis, showed their 

 highest oxidizing ability in the earlier stages of growth, while Phaseolus, Pisum, and Lu- 

 pinus showed their greatest oxidizing ability in the later stages of growth. The oxidizing 

 capacity of roots is related in a practical way to the oxidation processes in the soil. — A. T. 

 WianJfco. 



2177. KoPELOFF, Nicholas. The prevention of sugar deterioration by the use of super- 

 heated steam in centrifugals. Louisiana Planter and Sugar Manufacturer 65: 189-190. Fig. 

 1. 1920. — By using superheated steam in the centrifugals to wash the sugar, 92-99.5 per cent 

 of the bacteria and mold spores are killed. This improves the keeping quality of both the 

 sugar and the molasses. — C. W . Edgerton. 



2178. Lattpper, G. Die neuesten Ergebnisse der Heubrandesforschung. [Results of 

 recent investigations on the heating of hay.] Landw. Jahrb. Schweiz 1920: 1-54. Fig. 

 1-5. 1920. — This gives a detailed account of the physiological changes occurring in the heat- 

 ing of hay in the stack. Citations (65) of the literature are appended. — J. D. Luckett. 



2179. McDowALL, R. J. S. A review of recent work on enzyme action. Sci. Prog. [London] 

 15: 406-4.34. 1921. — A review of the more recent literature dealing with the nature and ac- 

 tion of enzymes is given. The work done in the various phases of this subject is correlated, 

 and from the indications of recent work there are pointed out the lines along which solutions 

 of many of the problems may be found. — J. L. Weimer. 



2180. Onslow, Mitbiel Wheldale. Oxydizing enzymes. II. The nature of the enzymes 

 associated with certain direct oxidizing systems in plants. Biochem. Jour. 14:535-540. 1920. — 

 This paper deals with the relation of a substance with catechol grouping to the oxidase system. 

 Solutions of various substances having this grouping, such as catechol, caffeic acid, proto- 

 catechuic acid, adrenaline, etc., were found to oxidize slowly in air with the formation of per- 

 oxides. A solution of peroxidase added to such peroxides completes an oxidase system, which 

 will blue guaiacum. The autoxidation noted above as concerns catechol, protocatechuie 

 acid, and caffeic acid is accelerated by enzyme extracts of plants which turn brown on injury 

 and the juices of which blue guaiacum without the addition of H2O2. In a previous com- 

 munication, such plants were shown to contain a compound with the "catechol" grouping 

 and the writer suggests here that they may contain, in addition, a second enzyme, for which 

 she tentatively adopts Bach and Chodat's term, "oxygenase." The function of the latter 

 is to catalyse the autoxidation of the catechol compound with the formation of a peroxide. 

 In the case under discussion, 3 components are considered as making up the oxidase system, — 

 a catechol compound from which a peroxide can be formed, and 2 enzymes, an oxygenase which 

 catalyses the production of a peroxide, and a peroxidase which decomposes the peroxide with 

 the formation of active oxygen. All 3 components are necessary for the bluing of guaiacum. — 

 A. R. Davis. 



2181. Onslow, Muriel Wheldale. Oxidizing enzymes. III. The oxidizing enzymes 

 of some common fruits. Biochem. Jour. 14: 541-547. 1920. — Enzyme action in plant tissue 

 may be difficult of demonstration due to the presence of certain inhibitors as well as to faulty 

 technique. Best results are usually obtained when the tissue is placed directly in the reagent. 

 When tissue extracts are employed action may be modified by (1) failure to extract the enzyme 



