AGEICULTURAL BOTANY. 27 



and the amount of dry matter was determined. The results of these experi- 

 ments seem to confirm those of the observations made in the field. 



The author is led to believe that assimilation is limited more by the propor- 

 tion of carbon dioxid available than by the intensity of the light. 



The effect of supraniaxim.al tem.peratures on plants, W. W. Lepeschkin 

 {Ber. Dcut. Bot. Gesell, 30 {1912), No. 10, pp. lOS-ll-',, figs. 2).— A discussion 

 is given of the effect of temperatures above the maximum for plant functions. 

 Experiments were conducted with Tradescantia and beets and the coagulation 

 of the protoplasm by the high temperatures was observed. The relation be- 

 tween temperature and duration of exposure is shown by a series of curves 

 and comparisons are drawn between these curves and the logarithmic curves 

 based on the relation of light to temperature. 



Is the form of trees determined by wind? P. Jaccaed {Jour. Forest. Suisse, 

 1912, pp. 129-1.',0; abs. in Bot. Centbl., 122 {1913), No. 1, p. 5).— Among the 

 causes which influence more or less strongly the activity of development of 

 various aerial portions of trees, the author notices especially the variations 

 in intensity and rapidity of the ascending water current. Comparison of sec- 

 tions of the roots with those of the trunk and branches, also of their anatomi- 

 cal structure, leads him to the conclusion that rapidity of water transport to 

 the various vegetal organs plays an essential part in the rate of development, 

 and that the variations therein observed are determined much more by trophic 

 than by mechanical factors. 



Sex anomalies produced in Japanese hops and hemp by diminished trans- 

 piration, J. TouRNOis (Coniftt. Rend. Soc. Biol. [Paris], 73 {1912), No. 37, 

 pp. 721-723). ^In previous publications (E. S. R., 27, p. 827) the author pointed 

 out the influence of late seeding and of strong sunlight on the abnormal flower- 

 ing of Japanese hops and hemp. Subsequent experiments, which are described 

 in the present paper, show that seedlings gro\%ai in dry and saturated air 

 presented marked anomalies where the transpiration was materially reduced. 



On the value and a new method of estimating the respiratory quotient 

 of green plants, L. Maquenne and E. Demoussy {Compt. Rend. Acad. Sci. 

 [Paris]. 1.56 {1913). No. I,, pp. 278-283).— In a previous publication (E. S. R., 

 28, p. 631) the authors have described methods for estimating the respiratory 

 quotient of plants. In testing these methods there has been found to be a 

 constant error of about one-fiftieth of the total, especially when the respiratory 

 quotient is near 1. The authors have determined the respiratorj' quotient at 

 a temperature of 25° for a large number of species of plants, from which it is 

 learned that the respiratory quotient of green leaves is always greater than 1 

 during the active period of vegetation. A decrease in the respiratory coefBcient 

 below unity is a sign of degeneration. 



The new method described is based on the estimation of the relative propor- 

 tion of nitrogen in the air of closed vessels in which plants are placed. In 

 nearly every instance the quantity of nitrogen was found greater at the end 

 of the experiment than at the beginning. 



Apparent fallacies of electrical response in cotton plants, W. L. BalLvS 

 {Ami. Bot. [London], 27 {1913), No. 105, pp. 103-110, fig. 1).—A description is 

 given of experiments with cotton plants, conducted to determine their healthful- 

 ness, by the method employed by Waller in his experiments on electrical re- 

 sponse or blaze currents in plants (E. S. R., 26, pp. 227, 228). The experiments, 

 in attempting to utilize electrical response as a test for health in Egyptian cotton 

 plants, resulted unsuccessfully. Improvements were devised, consisting of a 

 better method of control and a method of balance, and it is thought that by 

 their application the healthfulness of plants can be determined. 



