June, 1920] PHYSIOLOGY 415 



Fehling solution is added. The precipitate funned is finally weighed and considered MCOppeT 

 oxide; from the amount <>f this the reducing power of the extract is calculated as though the 

 latter had been a solution of dextrose. Numerous del nils of technique are given; each oper- 

 ation is to be performed in a standard manner. — The method was tested in a number of ways. 

 Assuming that photosynthetic activity is proportional to the Standardized copper-oxide 

 differences, reckoned as dextrose-equivalents, the following are example! of the results ob- 

 tained. Phaseolus leaves showed successively larger activity values, hour by hour, from 8 

 a.m. to 1 p.m., after which the values were successively smaller. The net activity of inverted 

 Ilelianthus leaves was higher than that of leaves in the normal position. In the foliar rosette 

 of Taraxacum the upper leaves showed values about twice as great as those shown by the low- 

 est leaves. When the light intensity (as measured with photo-sensitive paper) was reduced 

 from 100 to 10 the photosynthetic activity of Phaseolus leaves was correspondingly reduced 

 from 100 to G, while a light intensity reduction from 100 to 0.3 showed a net photosynthesis 

 reduction from 100 to only 2.0. Stamens of Acer nedundo showed a net activity of about 8 

 mgm. of dextrose per gram of dry tissue per day. Comparisons of Equisetum, Ilelianthus, 

 and Phaseolus showed relative transpiring powers (per areal unit) of 1580, 980, and 650, re- 

 spectively, for the three plants, while the corresponding photosynthetic values were 1500, 

 2802, and 4491; photosynthetic power appeared to be roughly inversely proportional to trans- 

 piring power. The presence of rusts or mildews decreased the net photosynthetic activity 

 of leaves in the cases tested; erumpent Puccinia reduced the activity values for Avena leaves 

 from 100 to 4S. A similar reduction for Phaseolus leaves accompanied serious infection by 

 Tetranychus (red spider). [Author's abstract of this paper was preliminarily published as 

 Physiol. Res. Prel. Abst., v. 2, no. 6, May, 1919! Full paper also appeared, reprinted 

 without change, in limited edition, as Ph.D. dissertation from Univ. Minnesota.] 

 [See also Bot. Absts. 3, Entries 1375, 1452, 2685.]— B. E. Livingston. 



METABOLISM, GENERAL 



2834. Anonymous. The anthocyanin pigments in plants and their chemical, physiological 

 and biological functions. Review of a number of recent papers and books on the anthocyanin 

 pigments of plants. Sci. Amer. Suppl. 84: 2-3, 7. 1919. 



2835. Appleman, C. O., and J. M. Arthur. Carbohydrate metabolism in green sweet 

 corn during storage at different temperatures. Jour. Agric. Res. 17: 137-152. 2 fig. 1919. — 

 The character and kinetics of the processes involved in the rapid depletion of sugar in Sto- 

 well's evergreen sweet corn when it is picked in the milk (or edible) stage has been studied in 

 connection with the effects of different storage temperatures on these processes. From an 

 initial sugar content of about 4.5 to 7 per cent (3.5 to 5 per cent sucrose and 1 to 3 per cent 

 reducing sugars) the sugar content falls off until, at equilibrium, about 1.5 per cent total sugars 

 remain. At the point of equilibrium about 62 per cent of the total sugar and about 70 per 

 cent of the sucrose has disappeared. At 30°C. about 50 per cent of the total sugar and 60 

 per cent of the sucrose is lost during the first 24 hours. The losses of total sugar in the same 

 time at 20° and 10° are respectively about 25 per cent and 15 per cent. Until about 50 per 

 cent of the total sugars are lost a temperature coefficient of about 2 was found for tempera- 

 tures from 0° to 30°C. The loss in sugar is due primarily to a transformation to polysac- 

 charids, chiefly starch, and even at the higher temperature, 30°C, only about 0.1 per cent of 

 the loss was due to respiration. — Otis F. Curtis. 



2836. Asai, Toichi, and Makato Nakamuro. Uber einen kristallinischen Bestandteil 

 von Gardenia florida L. [A crystalline constituent of Gardenia.] Bot. Mag. Tokyo 33: 70-71. 

 1919. — The authors describe the isolation of d-mannin from the flowers of leaves of Gardenia. 

 They also found a chromogen in various parts of this plant and other Rubiaceae which colors 

 intensely blue-green with mineral acids. — Leonas L. Burlingame. 



BOTANICAL ABSTRACTS, VOL. Ill, NO. 6 



