94 PHYSIOLOGY [BoT. Absts., Vol. VIII, 



enzyme, not total enzyme. The hypothesis has been put in the form of a differential 

 equation and found to agree quantitatively with the experimental results when the concen- 

 tration of pepsin, peptone, or both is varied. An integral equation is obtained which holds 

 for the entire course of digestion with varying enzyme concentration. Many analogies be- 

 tween the action of pepsin on albumen and the action of toxins on organisms are pointed out. 

 —Otis F. Curtis. 



650. Staehelin, M. Die Rolle der Oxalsaure in der Pfianze. Enzymatischer Abbau des 

 Osalations. [The role of oxalic acid in plants. The splitting off of the oxalate ion by enzyme 

 action.] Biochem. Zeitschr. 96: 1-49. 1919. — This is a detailed study of the enzyme in vari- 

 ous plants capable of hydrolyzing oxalic compounds. A brief review of previous work deal- 

 ing with acid metabolism of succulents is presented. The author sets out to determine the 

 following points: (1) The distribution of the enzyme in different types of plants, that is, in 

 nonsucculents and succulents of widely differing genera, (2) determination of an oxalate 

 enzyme in acid-free plants, (3) distribution of the enzyme in the plant tissues, and (4) the 

 kinetics of the reaction. — The objects studied covered chlorophyllous cryptogams and 

 phanerogams, both in green and etiolated stages. In general the experimental methods 

 comprised the incubation of the enzyme-containing plant powder with a solution of an oxalic 

 acid salt, preferably ammonium oxalate. At the close of the experiment the residual oxalate 

 was quantitatively determined. CO2 determinations were made with standard Pettenkoffer 

 and titration methods. — The chief results are as follows; Green leaves, stems, roots, etiolated 

 organs, and chlorophyll-free seeds of all plants studied contained an oxalate-hydrolyzing 

 enzyme. The pressed out juice as well as the powder precipitated by alcohol, possessed 

 enzyme activity {Helianthus leaves). This action is greatest between 30 and 40°C., and is 

 in large measure dependent upon oxygen supply. It is completely inhibited in an atmos- 

 phere of hydrogen. Increased oxalate concentration is correlated with a relative decrease 

 in hydrolysis, hydrolysis increasing with the square root of the enzyme increase (rule of 

 ScHtJTz). With a preparation of Rumex leaves, enzyme action conforms to a mono-molecular 

 equation, while with a powder from Helianthus leaves there is a deviation from the law of 

 auto-catalysis. The enzyme is an oxidase, and appears to have the properties of a carboxy- 

 lase. The oxalate ion is not completely oxidized by the enzyme to CO2 (doubtful in case of 

 Pisum). Other disintegration products were not determined. — W. W. Bonus. 



651. Wohlgemuth, J. tJber neue Theorien der Diastasebildung und Diastasewirkung. 

 [On new theories of diastase formation and action.] Biochem. Zeitschr. 95: 212-224. 1919. — 

 A discussion of the work of G. Wocher, supplemented by a brief account of experiments, 

 opposing the conclusions of Wocher that formaldehyde exerts an enzyme-like action on 

 starch, similar to diastase action. — W. W. Bonus. 



METABOLISM (RESPIRATION) 



652. Cerighelli, Raoul. Sur les echanges gaseux de la racine avec I'atmosphere. [The 



gaseous exchange beween roots and atmosphere.] Compt. Rend. Acad. Sci. Paris 171: 575- 



578. 1920. — ^A study of attached and detached roots in which the oxygen intact and the carbon 



CO 

 dioxide liberation was determined. The -— - ratio has a value varying from 0.7 to 1.0 accord- 



O2 



ing to the species. Respiration is higher in free humid air than in confined or dry atmos- 

 phere. In the case of a confined atmosphere such as occurs normally in the soil the CO2 is 

 retained in the tissues. In dry open air the ratio however is the same as in free humid air 

 although the amount of gases exchanged is decreased. — C. H. Farr. 



653. Langdon, S. C., and W. R. Gailey. Carbon monoxide a respiration product. Sci. 

 Amer. Monthly 1: 508-510. 3 fig. 1920. [Reprinted from Jour. Amer. Chem. Soc, 42: 641- 

 646. 1920.]— The existence of several per cent of carbon monoxide gas in the pneumatocyst 

 (i.e., floater) of the giant Pacific Coast kelp, Nereocystis hietkeana, is confirmed. It is con- 

 cluded that this is formed as a product of respiration rather than as an intermediate step in 

 photosynthesis. — Chas. H. Otis. 



