430 EXPERIMENT STATION RECORD. [Vol. 37 



on the inhibition of oxidase by acids, no experiments being made In alkaline 

 solutions owing to the inadequacy of the technique at present available. 



The experiments, while not sufficiently numerous to establish clearly the 

 relationship between oxidase activity and hydrogen ion concentration, suggest 

 the agency of two factors, the direct destructive effect of acidity on the active 

 matter and the retardation of oxidation rate by the hydrogen ions. These 

 factors may prove to be easily separable. 



It appears that the hydrogen ion concentration for each type of plant ma- 

 terial covers only a comparatively narrow range, a fact which may prove to 

 be Important. It would seem that the nature of the material related to oxidase 

 activity is identical in closely related plants. 



Just what particular agency is responsible for oxidase activity is not yet 

 determined, although it is widely distributed in nature. Active and inactive 

 modifications probably exist side by side, some characteristics noted strongly 

 suggesting the agency of colloids. 



Evidence of the action of oxidases within the growing plant, J. H. Kastle 

 and G. D. Buck.ner (Jour. Amcr. Chcm. Soc, 39 (1917), Xo. 5, pp. 47S-4S2).— 

 The authors have attempted to establish the presence of oxidases and avail- 

 able oxygen in growing plants. Sweet com and okra were injected with 

 phenolphthalein, then sectioned and tested with alkali, which showed the pink 

 coloration of phenolphthalein mostly above the point of injection and in some 

 instances extending nearly to the leaf tips. The reagents seem to have travele^l 

 along the vascular bundles, spreading in some cases into the neighboring cells. 

 The facts ob.served are considered to show the occurrence of oxygon and oxida- 

 tion in the living cells in both monocotyledons and dicotyledons. 



The occurrence and physiological significance of flavone derivatives in 

 plants, K. Shibata, I. Nagai, and M. Kishida (Jour. Biol. Chcm., 28 (1916), 

 No. 1, pp. 9S-108, pi. 1). — The authors, continuing the work previously noted 

 (E. S. R., 36. p. 329) on flavone derivatives and their relations to other bodies, 

 such as anthocyanin, have carried on a series of studios on the occurrence and 

 the physiological and biological significance of such substances in plants. 



It is claimed that a general occurrence of flavone derivatives in plants Is 

 now established, but that these, with a few exceptions notoil. iire limited al- 

 most exclusively to the epidermis and the peripheral parenchymatous layer 

 of the aerial parts. It is assumed that flavone derivative solutes in cell sap 

 are important as aiding absorption of ultraviolet waves and as thus pro- 

 tecting the protoplasm and its biochemical activities. This assumption is said 

 to have been supported by observations on plants from alpine and tropical 

 regions where the sun's rays are inten.se. the plants grown in strong insolation 

 being always rich in flavones except in case of those protected by anatomical 

 and morphologic.il peculiarities. Green leaves of deciduous trees, destined to 

 produce anthocyanin pigment in autumn, are said to contain considerable 

 flavone, the production of autumnal anthocyanin color being due to the re- 

 duction of such flavones and initiated by physiological conditions at the end 

 of the growing season. 



The acidity of plant cells as shown by natural indicators, A. R. Haas 

 (Jour. Biol. Chem., 27 (1916), No. 1, pp. 23S-241).— The author has endeavore<l 

 to ascertain to what extent natural Indicators in living cells can be utilized 

 to determine their reaction (the actual acidity of the dissociated hydrogen 

 ions as contrasted with the total acidity, which includes both dissociated and 

 undlssoclated hydrogen Ions). He has found that the reaction of the sap In 

 some entirely normal cells may be decidedly acid and that a blue color In living 

 cells does not necessarily indicate an alkaline reaction, also that in a dying 

 cell a considerable alteration of reaction may occur. 



