28 EXPERIMENT STATION RECORD. 



translocation, and use of the reserve i)roteids, and that they are actively con- 

 cerned in the nntrition of the pollen tube in its development. 



A method for the rapid recognition of hydrocyanic acid in plants, M. 

 MiBANDE {Compt. Rend. Acad. 8ci. [Paris], U9 (1909), No. 2, pi>. I't0-l'f2).— 

 The author has found that by introducing specimens of plants containing glu- 

 cosids that yield hydrocyanic acid in tubes or flasks containing chloroform and 

 a fragment of the picric-sodium pjiper described by Gulgnard (E. S. K., 18, 

 p. 626), the presence of hydrocyanic acid is quickly determined by the change 

 in the color of the pai)er. 



By making experiments with vapors of mercury, carbon bisulphid, chloroform, 

 ether, etc., it was found that under the influence of vapors which susi)end the 

 chlorophyll function of plants the plants conttiiniug hydrocyanic compounds 

 will give off the acid, and that even after the plants are dead the action will be 

 continued for some time. 



This forms a simple method for the recognition of hydrocyanic acid in plants, 

 and by this means it has been possible to show the presence of that compound 

 in plants where the ordinary methods of maceration and distillation failed. 



The influence of anesthetics and freezing on the splitting up of glucosids 

 in plants, L. Guignard iVoiiiiit. Rend. Acad. /S'c(. [I'aris], I'/D ilDOO), Xo. 2, 

 pp. 91-93). — Attention is called to the method of Mirande (see above) for the 

 rapid demonstration of the presence of hydrocyanic acid in plants, and in addi- 

 tion to anesthetics, freezing of plants is said to result in a similar manner. 



The elaboration of nitrogenous material in the leaves of plants, G. Andre 

 (Compt. Rend. Acad. ^ci. [I'an-s], l.'iS (1909), No. 25, pp. 1685-1687) .—A study 

 was made of the nitrogen content of chestnut trees at various stages of their 

 growth. 



The highest total nitrogen was found at the earliest date of examination, May 

 13, and the proportion of nitrogen to dry matter decreased regularly throughout 

 the season. The percentage of amid nitrogen to total nitrogen was greatest just 

 after the leaves had attained full size. It fell off quite sharply toward the 

 flowering period, after which there was a progressive increase until the end of 

 the season. The amount of nitric nitrogen found was small at the beginning, 

 and soon was represented by a mere trace. The small amount of nitric nitro- 

 gen present raised the question as to the source of nitrogen in the metabolism 

 of the plant, and it is thought probable that some other source of nitrogen must 

 be available than the nitrates obtained from the soil. 



The reduction of assimilation by plants during cloudy weather, A. MiJNTz 

 and H. Gaudechon (Compt. Rend. Acad. Sci. [Paris], 1J,9 (1909), No. 3, pp. 190, 

 191; Bui. Soc. Nat. Agr. France, 69 (1909), No. 7, pp. 63S-635 ) .—The authors 

 have investigated the relation existing between the illumination of plants and 

 their carbon dioxid assimilation. Experiments were conducted with wheat plants 

 in which the illumination was varied to correspond to different degrees of cloudi- 

 ness, and the oxygen given off was determined as a measure of the carbon 

 dioxid assimilation. In direct sunshine the plants were found to assimilate 

 4 or 5 times as much carbon dioxid as was the case under heavy clouds and 

 rainy weather. 



From these data the authors have computed the rate of assimilation per 

 hectare for wheat and find that on a bright day a hectare of wheat would 

 assimilate carbon dioxid sufficient to form 22 kg. of starch, representing 33 kg. 

 of wheat, while on an overcast day the amount assimilated would correspond 

 to 4.7 kg. of starch, representing 7 kg. of grain. 



The authors conclude that in France a large proportion of cloudy days during 

 June and the first half of July will materially reduce the harvest through the 

 reduction of chlorophyll activity on the part of the plants. 



