1916] AGEICULTURAL BOTANY. 633 



It is stated that the reactions of Avena to gravitational stimuli and to light 

 stimulation of small intensity do not noticeably influence each other. By vary- 

 ing the duration and the intensity of illumination, modifications were produced ; 

 namely, the reversal of the direction of curvature and a change in the rate of 

 reaction. 



Detei-mination of cell sap concentration by the freezing point method, 

 G. J. BouYoucos and M. M. McCool {Jmir. Atner. Soc. Agron., 8 {1916), No. 1, 

 p. 50). — In the present brief note attention is called to the fact that as a result 

 of the successful application of the freezing-point method in a study previously 

 reported (E. S. R., 34, p. 721), this method can now be employed to investigate 

 many other problems. It is stated that the determination of the concentration 

 of the plant cell sap can be accomplished directly in the plant without extracting 

 it by crushing the plant tissue, placing it in the freezing tube, inserting the 

 thermometer, and following the procedure described. The results of the consid- 

 erable work already done have fulfilled anticipations, inasmuch as the concen- 

 tration of the cell sap is greater when determined directly in the plant than 

 after extraction. 



The transpiration coefficients of cultivated plants, N. Tulaikov (Tou- 

 laikoff) {Zhur. Opytn. Agron., 16 {1915), No. 1, pp. 36-76, figs. 4; abs. in 

 Intemat. Inst. Agr. [Rome'\, Mo. Bui. Agr. Intel, and Plant Diseases, 6 (1915), 

 No. 6, pp. S13-S15). — This is an account of the study at the Besentchuk Agri- 

 cultural Experiment Station during 1910 to 1914, in the culture house and in 

 the open, of the transpiration coefiicient or the amount of water necessary to 

 form a unit of dry matter. 



The results, which are tabulated, are considered to show that the variations of 

 the transpiration coefficient of a given plant are sometimes larger in different 

 years than for different species in the same year. The numerical coefficient in 

 the open was about twice as large as that in the culture house, but its volume 

 depends upon meteorological conditions in the same way as in the former case. 

 Early sowing gives a large crop and a low transpiration coefficient, late sowing a 

 high transpiration coefficient but a lessened C|jop. The coefficients of wheat and 

 oats in rows are lower than in the same crops sown broadcast. In 1914 the 

 largest crops of summer wheat and oats corresponded to the lowest water 

 consumption. 



Assimilation of carbon dioxid by plants, P. N. Raikow {Chem. Ztg., 39 

 {1915), No. 105, pp. 657-659; abs. in Jour. Chem. Soc. [London], 108 {1915), No. 

 637, I, pp. 1047, 1048). — A theory herein set forth intended to explain the 

 assimilation of carbon dioxid by plants is based largely on the properties of 

 chlorophyll and the presence of an oxonium compound. According to this view, 

 the oxygen liberated is probably derived one-half from carbon dioxid and one- 

 half from water. 



Importance of glycogen and starch as intermediate products in the trans- 

 formations induced by certain organisms, H. I. Waterman {Chem. WeeJcbl., 

 12 {1915). No. 24, pp. 552-556; abs. in Jour. Chem. Soc. [London], 108 {1915), 

 No. 633, I, p. 630). — Details are given of an investigation of the percentages of 

 invert sugar, sucrose, and starch present in bananas dried at temperatures 

 between 45° and 105° C. 



Recent studies on the chemical and histological characters of radish cul- 

 tivated in the presence of sugar, M. Molliaed {Rev. G^n. Bot., 27 {1915), No. 

 318, pp. 161-168, pis. 2, figs. 2). — Studies pursuant to those previously reported 

 (E. S. R., 19, p. 932), employing sugar solutions of different strengths, show 

 resulting alterations, which are described, in tissue structure and cell content. 



