822 EXPEEIMENT STATION RECORD. 



jected to full shade, half shade, consisting of lath cover and wooden sides, and 

 half shade with wire sides, and in pine woods. 



The data gathered seemed to show that the shading of young trees is a 

 matter of evaporation rather than one of light, as is generally stated. The 

 average amounts of daily evaporation at the different stations were as follows: 

 Control 45 cc, full shade 19 cc, half shade with solid sides 20 cc, half shade 

 with wire sides 43 cc, and in pine woods 16 cc. Of these amounts from 17 to 

 25 per cent was lost during the 12 hours from 6 o'clock p. m. to 6 o'clock a. m. 



A balancing method for differentiating between absorption and transpira- 

 tion, L. J. Briggs and H. L. Shantz [Abs. in Science, n. ser., 35 (1912), No. 

 891, p. 15S). — -The authors give a description of a form of apparatus for dif- 

 ferentiating between absorption and transpiration by plants. This consists 

 essentially of potted plants suspended upon knife edges in a horizontal position 

 and so balanced by counterweights and the center of gravity so adjusted as to 

 secure the required sensibility. By means of this method water loss through 

 transpiration may be determined. The method is said to be also adapted to the 

 determination of the wilting coefficient of plants, which, owing to structural 

 peculiarities, do not wilt when the moisture content of the leaves is reduced. 



A further study of the influence of temperature on the respiration of 

 the higher plants, J. Kuypeb (Ann. Jard. Bot. Buitenzorg, 2. ser., 9 {1911), 

 pi. 1, pp. Jfo-oJi, pis. 2). — The author continued his investigations along the 

 lines previously marked out by F. F. Blackman, A. M. Smith, H. M. Ward, and 

 himself (E. S. R., 17, p. 234; 18, p. 923; 24, p. 533; 25, p. 220; 26, p. 227) with 

 reference to the respiration of tropical plants. From the results of his ex- 

 periments he concludes in brief that the influence of temperature in the case 

 of the tropical plants investigated is the same as that found to operate in plants 

 of the Temperate Zones, and that his findings are in general confirmatory of 

 Blackman's views. 



Periodical daily fluctuations of respiration in foliage leaves in darkness 

 and their possible bearing upon carbon-dioxid assimilation, A. Meyek and 

 N. T. Deleano {Ztschr. Bot., 3 {1911), No. 10, pp. 657-701, figs, ii).— Besides 

 discussing the results of their own previous work and that of others in this 

 connection, and giving a rather extensive bibliography, the authors report in 

 some detail on their own later experiments. 



These were carried out with leaves of Vitis vinifera, Acer psencloplatanus, 

 and Rubiis idwiis to ascertain the daily variation of carbon-dioxid evolution 

 both during and after a period of traumatic stimulation due to the separation 

 of the leaves from the plants. During that reaction period, which tended to be 

 repeated with each injury to the leaves, there was normally a heightening of 

 the process to a maximum reached in from about 1 to 3 days, and after this 

 a lowering to a medium rate of carbon-dioxid evolution for each case. About 

 this medium the rate showed a daily fluctuation, differing in degree in different 

 experiments, the daily curve exhibiting such factors as time, temperature, 

 nature and degree of wounding, etc. The stomata seemed to have no sig- 

 nificance in connection with this daily periodicity. Different kinds of leaves 

 were found to possess specific capacities for carbon-dioxid production. The 

 maximum rate tended to be reached in the daytime, or in the period of stimu- 

 lation following illumination. This tendency lends support to the hypothesis 

 that respiration is an essential part of the process of assimilation. 



The influence of phosphates on the separation of carbon dioxid by plants, 

 L. IwANOFF {Biochem. Ztschr., 25 {1910), No. 2-3, pp. 171-186).— The author re- 

 ports that he finds from his investigations on wheat and pea seeds, as well as 

 with yeast fermentation, that both aerobic and anaerobic evolution of carbon 

 dioxid is accelerated by the influence of phosphates. 



