482 EXPERIMENT STATION KECOED. 



The euergy of the deconipositiuu ui' caiixm dioxid Tor :i greeu leaf in a colored 

 light depends upon the absorption of the different colors by the chlorophyll in 

 regard to their calorific energy. The true fixation of carbon by a plant 

 expressed by the increase in dry matter in the course of its growth is unequally 

 influenced by the difterent rays of the solar siDectrum. The maximum of dry 

 matter corresponds to the blue violet rays and not to the red rays of the 

 spectrum. The increase in dry matter with the yellow orange rays was less 

 than that of the red and is least with the green rays. 



If photosyntliesis is divided into .2 parts, then the first stage is characterized 

 by the decomposition of carbon dioxid and the synthesis of the first organic 

 products. The plants utilize to a great extent during this stage the red rays 

 of the solar spectrum. 



The second stage is characterized by the definite fixation of the primary 

 organic substances elaborated in the green cells, and the ])lant employs for 

 this work the blue violet rays. 



Pigment formation in cultures of Azotobacter chroococcum, W. L. Omeli- 

 ANSKY and O. P. Ssewerowa {Centbl. Bnkt. [c/c], 2. AM., 29 (1911), No. 23-25, 

 pp. 643-650, fig. 1 ) . — After a review of the literature on this subject, the authors 

 give the results of their experiments on pigment formation by A. Ghroococcum. 



It was found that certain strains of this bacterium were characterized by the 

 formation of pigment which was more quickly produced when old, brownish 

 cultures were used as a source of inoculating material. This pigmentation 

 occurred best at an optimum temperature of about 30° C, under well aerated 

 conditions, and in a dextrin agar medium to which lime carbonate had been 

 added. The pigment is insoluble in the usual solvents, but can be dissolved 

 in the presence of an alkali. 



On the relative amount of mineral foods in soils and their relationship to 

 plant growth, D. Dezso (VcrhaiuU. Iiitcniat. Aijrogeol. Konf. {Stockholm], 

 2 {.1910), pp. 178-196). — In a study of the relationship of mineral foods to plant 

 growth the author found that the greater the relative amount of soluble min- 

 eral foods in the soil compared to the soil moisture present, the more vigorous 

 was the plant growth on such soils; that is, the denser the mineral food solution 

 of a given soil, which density is dependent upon the available amount of soluble 

 salts and on the average water content of the soil, the more food would the 

 plants have, and therefore the more vigorously would they gi'ow. 



The retention of mineral matter by annual plants; the distribution of 

 the fixed elements, G. Andr:^: {Compt. Rend. Acad. Sci. [Paris], 152 {1911), 

 No. 14, pp. 965-967).— In previous papers (E. S. R., 25, p. 325) the author gave 

 the results of investigations on the retention of mineral matter by annual 

 plants and on the distribution of dry matter, total ash, and nitrogen content. 

 In this article the distribution of the phosphoric acid, potash, lime, and mag- 

 nesia in each organ is given for 5 different periods in the growth of the plant. 



The distribution of the phosphoric acid was found to be more regular than 

 that of the nitrogen, and reached its absolute maximum weight in roots, stems, 

 and leaves at the beginning of the fruiting period, when it diminished to the 

 end of the growth of the plant. In the fruits the phosphoric acid increased 

 with the same rapidity as the niti'ogen during the active period of matui'ation. 

 The potash varied essentially the same as the nitrogen. The lime and magnesia 

 increased in absolute weight in all the organs, but toward the close of the plant 

 growth the weight of these 2 bases diminished in the leaves. 



The relationship of organic phosphorus to amido-nitrogen and to non- 

 proteid nitrogenous compounds in ripe seeds, A. Parrozzani {Rend. Soc. 

 CMm. Ital., 2. scr., 1 (1909), pp. 205-207). — As the result of experiments with 

 the ripe grain of maize on the relationship of organic phosphorus to certain 



