No. 3, December, 1920] PHYSIOLOGY 193 



chloride, potassium phosphate, citric acid). The sugars present in the exterior liquid (sac- 

 charose, glucose) did not act in this way because they were not absorbed. At such tempera- 

 tures there is a lively autodigestion of protein, which is favored by the exosmosis of the sol- 

 uble products of the digestion and by the more rapid destruction of the sugars.— F. M. 

 Blodgett. 



MINERAL NUTRIENTS 



1313. Anonymous. [Rev. of: (1) Burd, J. S. Rate of absorption of soil constituents at 

 successive stages of plant growth. Jour. Agric. Res. 18: 51-72. 1919. (2) HoAGLAND, D. R. 

 Relation of the concentration and reaction of the nutrient medium to the growth and absorption 

 of the plant. Ibid. 73-117. 1919.] Nature 104: 446. 1920. 



1314. Maquenne, L., and E. Demoussy. Sur l'absorption du calcium par les racines des 

 plantes et ses proprietes antitoxiques vis-a-vis du cuivre. [The absorption of calcium by plant 

 roots and its antitoxic properties with respect to copper.] Compt. Rend. Acad. Sci. Paris 170: 

 420-425. 1920. —The antagonism of calcium and copper is studied with a view to determining 

 whether the former interferes with the penetration of the latter or if it aids the plant in resist- 

 ing the poison. Experiments were performed with pea seedlings in nutrient solutions contain- 

 ing either calcium sulphate, copper sulphate or a mixture of the two in certain proportions. 

 In some cases sand cultures were used and in others quartz tubes. With the latter the solu- 

 tions might be periodically renewed. — It was found that calcium does not reduce the permea- 

 bility of the roots to copper, nor does copper affect the absorption of calcium. Hence it is 

 not because of a modification in permeability that calcium is protective, nor does copper seem 

 to be injurious because of its shutting out nutritive materials. The antitoxic action of cal- 

 cium appears to be rather an internal effect, giving the plant an increased vigor to withstand 

 toxic substances and increasing the volume of the plant through which copper may diffuse 

 and interfering with its accumulation locally in the plant in sufficient quantity to become 

 injurious. — C. H. and W. K. Farr. 



PHOTOSYNTHESIS 



1315. Anonymous. [Rev. of: Riedel, F. Die Ausniitzung der Hochofenabgase zur Kohl- 

 ensaurediingung. (The utilization of blast-furnace waste gases as carbon-dioxide fertilizer.) 

 Stahl u. Eisen, 39 Jahrg. : 1497-1506. 1919.] Rev. Gen. Sci. Pures et Appliqueea 31: 132. 

 1920. — This paper, rather surprisingly widely noticed, reports the experiments of an engineer 

 familiar with the problems besetting the operators of manufacturing plants discharging dele- 

 terious fumes into the air under the methods in common use. Without any indication of the 

 means employed to separate the carbon-dioxide from the other gases accompanying it in the 

 stack, greenhouse and open plot experiments and controls are described, details seeming 

 desirable and usual to horticulturists and plant physiologists are omitted, and the results 

 are given both in graphs and w r ords. Thus the yield from tomato plants in a greenhouse into 

 which C0 2 was introduced through perforated pipes was 2f times the weight of tomatoes 

 from an equal number of plants in a similar greenhouse with ordinary air. Similarly cucum- 

 bers weighing a total of 138 kilos w y ere produced in an ungassed greenhouse while the yield 

 in a gassed house was 235 kilos, 1.7 times greater. Field experiments gave results showing 

 a gain varying from lh to nearly 3 times the yield in gassed plots over those bathed in ordi- 

 nary air. It may be pointed out that two photographs designed to show the advantage of 

 adding CO2 to ordinary air, and very striking in appearance, do not seem to be taken on the 

 same scale. There is no evidence that botanical literature on the subject has been consulted. 

 — G. J. Peirre. 



1316. Spoehr, H. A. The development of conceptions of photosynthesis since Ingen- 

 Housz. Sci. Monthly 9: 32-46. 1919. — The author presents in this paper a comprehensive 

 historical digest of the subject, emphasizing, in the earlier work, that of Ingen-Housz. It 

 is shown that step by step Ingen-Housz approached the correct interpretation in his experi- 



