308 PHYSIOLOGY [BoT. Absts., Vol. VII, 



16: 122-132. 1918. — 'On the basis of his experiments Rippel does not believe in the theory of 

 the conservation to the plant of the potassium, phosphorus, and nitrogen compounds, held by 

 some investigators as the explanation of the recession of these compounds during the yellow- 

 ing of the leaves in the fall. He thinks the reason for the early recession (even before yellow- 

 ing) of potassium from the leaf to the plant is to fulfill some at present unknown function 

 and that the later recession of phosphorus and nitrogen is due to the fact that during yel- 

 lowing of the leaf the transfer of substances from the leaf to the plant far outbalances the 

 flow into the leaf of such substances. — Orton L. Clark. 



PHOTOSYNTHESIS 



2127. Anonymous. Gas as a fertilizer. Sci. Amer. Monthly 1:562. 1920. — This is a 

 brief description of German experiments on the effect of increased amounts of carbon dioxide 

 on the growth and development of plants. — -Chas. H. Otis. 



2128. IVI cLean, F. T. Field studies of the carbon dioxide absorption of coco-nut leaves. 

 Ann. Bot. 34: 367-389. 1920. — -There is described a method of measuring the carbon dioxide 

 absorption of field crops in situ under conditions as little modified as possible. The method is 

 found to be satisfactorj* in studying the comparative rates of absorption of leaves from the 

 same plant or different kinds of plants, and also the same leaves at different times of the day. 

 Data obtained by this method show* that the middle-aged leaves of coconut absorb carbon diox- 

 ide more rapidly than young or mature leaves. The maximum rate of absorption is in the 

 morning, followed by a depression at mid-day, a second rise in the afternoon, and a final 

 decline towards sunset. Detached pinnae of a coconut leaf exhibit the maximum absorption 

 at a different time of day from that of the attached ones, but the rates of absorption are 

 similar in both cases. Abaca leaves are found to have an absorption rate similar to coconut 

 while those of sugar cane absorb carbon dioxide much more rapidly. — -Joanne L. Karrer. 



2129. Ravenn.\, C. Sulla formazione dell'amido nelle piante verdi. [The formation of 

 starch in green plants.] Atti R. Accad. Lincei Roma Rend. (CI. Sci. Fis. Mat. e Nat.) V, 

 29': 148-150. 1920.^The author replies to an article by Polacci (Atti Istit. Bot. Univ. 

 Pavia II, 27:29. 1917) criticising the author's previous article (Rendiconti V, 25i:649. 

 1916).— i^. M. Blodgett. 



2130. Wright, R. C. An apparatus for determining small amounts of carbon dioxide. 

 Amer. Jour. Bot. 7: 368-370. 1 fig. 1920.— The author has developed a light, compact, and 

 sensitive apparatus for measuring the amount of carbon dioxide in the air, for special use in 

 storage plants. Its structure and manipulation are described. — E. W. Sinnott. 



2131. WuRMSER, Rene. Action sur la chlorophylle des radiations de differentes longuers 

 d'onde. [The effect on chlorophyll of rays of different wave lengths.] Compt. Rend. Acad. 

 Sci. Paris 170:1610-1612. 1920.— Photochemical susceptibility is found to be related to 

 wave length in approximately the proportion of the absorption constants, except in the case 

 of minimum absorption where it decreases very rapidly. The radiation of the two principal 

 bands of red and violet are equally active for equal energy values.— C. H. Farr. 



METABOLISM (GENERAL) 



2132. BouRQUELOT, ET Bridel. Obtcntion biochimique du sucre de cane a partir du gen- 

 tianose. [Sucrose from gentianose by biochemical methods.] Compt. Rend. Acad. Sci. Paris 

 171:11-15. 1920. 



2133. CiAMiciAN, G., E C. Ravenna. Sul contegno di alcune sostanze organiche nei 

 vegetali. Nota XII. [Upon the behavior of some organic substances in plants.] Gazz. Chim. 

 Ital. 50: 13-46. Fig. 1-17. 1920.— This is a continuation of the work published by the 

 authors upon the action of organic substances on the growth of young seedlings of Phaseolus. 

 In the present contribution the plants studied were: Phaseolus, Cucurbiia, Vicia, and Lyco- 



