326 EXPERIMENT STATION EECOED. 



The permeability of the yeast cell, S*G. Paine {Proc. Roy. Soc. [London'], 

 Scr. B, SJi {1911), No. B 512, pp. 289-307). — Early experiments on plasmolysis 

 of yeast cells seemed to indicate that the envelope is impermeable by inorganic 

 salts, while readily permeable to alcohol, etc. Qnantitative estimations have 

 shown the power of diffusion of alcohol to be very different from that of inor- 

 ganic salts. Alcohol is believed to diffuse readily into the cell. All salts which 

 have been tried have been taken up by yeast from moderately concentrated solu- 

 tions, and in the case of sodium chlorid and ammonium sulphate even from 

 dilute solutions, but since the yeast must of necessity be analyzed as a whole 

 the question as to how far into the cells the various solutions have penetrated 

 must for the present remain in doubt. It seems very probable that the apparent 

 entrance of salts is the result of adsorption in the surface layers rather than 

 of absorption, or it may be that the salt particles are kept back by a differen- 

 tial septum according to the hypothesis of Armstrong (E. S. R., 21, p. 126). 



On the metabolic chang'es due to geotropic stim.ulation, II, V. Grafe and 

 K. LiNSBAUER {Sitzbcr. K. Akad. Wiss. [Vienna], Math. Naturw. El., 119 

 (1910), I, No. 8, pp. 827-852). — ^After giving brief notes on some work done by 

 others, the authors continue an account of their own investigations (E. S. R., 

 23, p. 723), seeking to establish a basis for a chemical theoiy of geotropism. 

 The resfilts were mainly negative. Geotropic stimulation was not found to be 

 connected with any regular difference in catalysis. 



On the precipitation of iron by lig'ht and by green aquatic plants, H. Mo- 

 LiscH (Sitsber. K. Akad. Wiss. [Tieuna], Math. Naturw. KL, 119 (1910), I, No. 8, 

 pp. 959-984, pi. 1 ) . — The author worked on the hypothesis that green submerged 

 aquatic plants are able to precipitate within themselves iron from solutions 

 and thereby to furnish material for bog iron ore. Experiments were conducted 

 with dilute solutions of iron compounds in light and in darkness, and also with 

 green aquatic plants in such solutions both exposed to light and protected 

 therefrom. 



It was found that while iron was precipitated spontaneously from some com- 

 pounds in darkness, from others it was deposited only in the light. In the 

 latter case the process was usually favored by the presence of the green plants, 

 of which Elodea canadensis deposited the red oxid of iron in the outer layers 

 of its epidermal cells, sometimes in concentric strata. In darkness the plants 

 usually showed no precipitation, or less, and that at a slower rate. 



The conclusion is reached that green aquatic plants probably play a certain 

 part in nature in the formation of iron ore beds. 



Peroxidase and the respiratory pigments of plants, W. Palladin and P. 

 IRAKLIONOFF (Rcv. G6n. Bot., 23 (1911), No. 270, pp. 225-2^7).— A study has 

 been made of yeasts, molds, and a number of higher plants to determine the 

 relation of peroxidase and the respiratory pigments which they may contain, 

 and the authors claim that their results have an important bearing on the 

 theory of normal respiration. 



They found that the quantitative distribution of peroxidase In plant tissues 

 coincided with that of the respiratory pigments. Tissues rich in peroxidases 

 were also well supplied with chromogens. In some plants the peroxidase is 

 found in a free state, while in others, such as pea seeds, it is in a fixed form. 

 The presence of albuminoid substances complicates the isolation and purifica- 

 tion of peroxidase. From such plants as the watermelon, pumpkin, etc., which 

 are very poor in albuminoids, the authors state that peroxidase may be readily 

 separated by precipitation with mercuric chlorid, but with wheat embryos the 

 isolation is less successful, and it fails altogether with peas. A solution of 

 sodium chlorid may be used for isolating peroxidase when water gives negative 

 results. Potassium phosphate was found to be an excellent solvent of 



