546 EXPERIMENT STATION RECORD. 



lichen Unlersuchung vnd BeurtheUnug von Xalirungi^- ^ind GenussmlUeln sowie Gebrduchs- 

 (fegtmtandenfur dai^ Veidsehc Reich. BerUn: J. Springer, pt. J, 1S97, pp. XIII + 109; 

 pt. 2, 1S9'\ pp. XII + 184; pt- 3, 1902, pp. X+ i^'-;^).— This work contains the methods 

 for the examination of foods, condiments, and commercial products decided upon by 

 a connnisslon of food chemists appointed at the request of the Imperial Board of 

 IleaUli. A valuable point to be noted in connection with the work is the very full 

 bibHography which accompanies each of the principal sections. 



The chemistry of India rubber, C. O. Webek {London: Charles Griffin & Co., Ltd.; 

 Philadelphia: J. B. Lippincott Co., 1903, pp. XI+314,pl'<. 5, fig.'^. IG). 



Analysis of resins, balsams, and gum resins, K. Dieterich, transl. by C. 

 Salter {London: Scott, Greemvood & Co., 1901, pp. XIV+340). 



Physical and chemical methods for the quantitative determination of 

 organic compounds, W. Yaubel {Die phymkaUschen und chemischen Methoden der 

 quanlHativen Bedimmung arganucher Verhindungen. Berlin: Jidivs Springer, 1902, vol. 

 1, pp. XIV— 593, figs. 74; vol. 2, pp. AT+ 530, figs. 21) .—Volume 1 deals with physical 

 methods and volume 2 with chemical methods. 



BOTANY. 



The influence of varying amounts of carbon dioxid on photosynthesis, H. T. 



Brown and F. Escombe {Proc. lioy. Soc. [London'], 70 {1902), No. 464, pp. 397-413, 

 pis. 6; abs. in Bot. Centbl, 90 {1902), No. 11, pp. 293, 294).— X series of plants was 

 experimented with to test the effect of varying amounts of carbon dioxid in the air 

 on tlie photosynthetic processes of the leaves and on the growth of the plants. In 

 one series leaves which were in some instances still attached to the plant were 

 inclosed in air-tight cases through which air was passed, and the carbon dioxid con- 

 tent determined both before and after its passage over the leaf. In these experi- 

 ments it was found that by increasing the carbon dioxid in the air an increase was 

 noted in the photosynthetic power of the leaf in nearly the same i)roportion. In all 

 cases where the illumination of the leaf was good, the photosynthesis was somewhat 

 in excess of what might be expected from the increased amount of carbon dioxid. 

 This was attributed to the fact that in the experiment the ah- which contained the 

 greater amount of the gas also carried more moisture than ordinary air. 



Experiments were conducted in a similar manner in which the illumination was 

 insufficient and similar results obtained. Seedling plants were experimented with 

 by inclosing them in vessels and subjecting them to varying amounts, of carbon 

 dioxid, the experiments indicating tliat the plants were not stimulated to increased, 

 growth by increasing the amount of carbon dioxid. On the other hand, there 

 appeared to be a slight diminution in the increase of dry matter and a less develop- 

 ment of leaf area. There were also certain morphological differences which are noted 

 elsewhere (see below). 



Similar experiments were conducted in a small greenhouse and carried on approxi- 

 mately from ] to 2 months. The effect of an increased amount of carbon dioxid 

 became most apparent within a week or 10 days of the beginnijig of the experiment. 

 A marked difference was noted in the habit and general appearance of the plants 

 owing to a stimulation of axial growth accompanied by a more or less pronounced 

 shortening and thickening of the internodes. As it appeared evident that the 

 increased photosynthesis did not contribute to the increase of dry matter of the 

 plant, it is concluded that the transformation, translocation, and metabolism of the 

 leaf reserves could not keep pace with the increased tendency to produce an extra 

 amount of plastic material from the atmosphere. Without exception all the plants 

 experimented with seemed to be best adapted to the atmosphere containing the ordi- 

 nary proportion of carbon dioxid. Tlie response which they made to slight increases 



