826 EXPERIMENT STATION RECORD. 



imported, the imports nearly trebling in the 5 years, 1907 to 1911. In the latter 

 year the imports amounted to 362,629 tons valued at $3,675,060. 



AGRICULTURAL BOTANY. 



The influence of the concentration of dissolved nutritive substances on 

 their absorption by plants, I. Pouget and D. Chouchak (Compt. Rend. Acad. 

 Sci. [Paris], i5^ (1912), No. 25, pp. 1709-1711, fig. i).— Contiuuiug previous 

 work regarding the relations between the concentration of dissolved nutritiv-j 

 substances and their absorption and assimilation by plants (E. S. R., 24, p. 

 423; 25, p. 127), the authors make the following statements: 



At very low concentrations (in case of phosphoric acid less than 0.1 mg. 

 per liter) absorption of the solute does not take place, but such substance 

 tends rather to pass from the cells containing it into the solvent in either 

 mineral or organic form. If, however, the concentration of the solute is con- 

 tinuously raised, absorption begins at a certain point (a) and its rate increases 

 faster than does that of concentration. At a second point (b) the two rates 

 become proportional and remain so to a third point (c) beyond which con- 

 centration increases faster than absorption, the latter now being regulated 

 not by concentration but by utilization of that solute by the cell. The general 

 course of these changes depends upon the particular substance absorbed, the 

 state of the plant, and the vegetative period in which it is tested. 



It was found that in very dilute solutions the absorption of nutritive sub- 

 stances was much greater than that of the water. The above results are held 

 to show (1) that soil water, in spite of its low content of the elements of fer- 

 tility, ought to play an important role in the elaboration of crops; (2) that is, 

 if the concentrations of all the elements necessary to the plant are higher 

 than the point (c), nutrition goes on normally and the crop does not depend 

 upon climatic conditions; but (3) if the concentration of such elements (or 

 even only of one, according to the law of minimum) is below that point the 

 crop returns will depend upon the concentration of that element. 



The influence of radio-active mineral on the germination and on the 

 growth of wheat, A. J. Ewart {Jour. Dept. Agr. yictoria, 10 {1912), No. 7, 

 j)p. ^17-421). — The author tested the influence of radio-active mineral, known 

 to accelerate germination of cereals, on the development of bacteria and on the 

 growth of wheat when applied as a manure. It was found that in the first 

 case a distinctly retardative action is exercised which becomes more pro- 

 nounced with longer exposures, and that in the second any early stimulating 

 efl'ect becomes converted into an injurious one on prolonged contact. He 

 concludes that, in practicable applications, radio-active material does not 

 appear to have any direct value for the growth of wheat. 



The action of uranium on the vegetable cell, C. Acqua {Arch. Farvmcol. 

 Sper. e Sci. Aff., IJf {1912), No. 2, pp. 81-8^). — Pursuant to previous investiga- 

 tions on the influence of radio-active substances on the life processes of plants 

 (E. S. R.. 24, pp. 230, 531) the author now reports that uranium can be absorbed 

 by certain cells of higher plants, in which it hinders karyokinesis, checking cell 

 division. This influence is said to be considerable in the tissues of the root 

 system, but much less so in the stem tissues on account of less ready absorption 

 there. Thorium and manganese are said to show somewhat analogous proper- 

 ties, but the latter in much less degree and in a way more compatible with the 

 development of the plant. 



The influence of narcotics on the chemical composition of plants. — I, The 

 chemical behavior of plants in acetylene atmosphere, V. Gbafe and O. 

 RicHTEB {Sitzber. K. Akad. Wiss. [Vienna], Math. Naturw. Kl., 120 {1911), 



