732 EXPEEIMENT STJLTIOIS EECOED. 



by means of freezing point of sap ; after which he describes Barges method 

 of determining molecular weights and its application to the estimation of 

 osmotic pressures of the cell sap of plants. Various species were studied by 

 ttiis method and the author claims twofold advantages for it. A very smaU 

 quantity of sap is sufficient for making the determination so that the osmotic 

 pressure of any small part of a plant may be estimated, and no elaborate ap- 

 paratus is required. There are, however, some disadvantages, as considerable 

 time must elapse between the readings, the tubes require to be filled with great 

 care, and the method does not allow for any chemical changes that might alter 

 the osmotic strength of the sap. 



Studies were made with Salicornia by this method and the cryoseopic method 

 and the results obtained varied within similar limits. 



Investigations on the nutrition of some of the higher plants in sterile 

 cultures, I. Shulov {Izv. Moskov, Selsk. Khoz. Inst. {Ann. Inst. Agron. Mos- 

 cou), 19 {1913), No. 3, pp. 1-216, pis. 4, figs. 16). — A detailed account of investi- 

 gations the principal results of which have been noted elsewhere (B. S. R., 

 29, p. 423). 



The assimilation of nutriment by yeast cells, M. Rtjbneb {Sitzber. K. 

 Preuss. Akad. Wiss., 191S, VIII, pp. 232-241).— The author states that the 

 intensity of fermentation by yeast cells is independent of the concentration of 

 the saccharin medium within vride limits. A solution of sugar was rapidly 

 weakened by either living or killed yeast without fermentation but with the 

 development of a certain amount of heat. 



In the fermentation of yeast the mass of protoplasm and not the amount of 

 surface appeared to determine the rate of peietration of nutritive material 

 through the cell wall. The rate of absorption of sugar is said to be in close 

 relation to the intensity of the life processes, varying with changes of tem- 

 perature and being depressed by the addition of alcohol or common salt. 



Yeast is said to stand high among those life forms which develop large 

 amounts of energy per unit of mass, its capability in this regard being sur- 

 passed only by that of some species of bacteria. 



Penetration of different fonns of nitrog^en into plants; phenomena of 

 adsorption, D. Chotjchak: {Compt. Rend. Acad. Soi. [Paris], 156 {1913), No. 

 22, pp. 1696-1701, figs. 2). — In continuance of work previously done in connec- 

 tion with I. Pouget (E. S. R., 27, pp. S23, 826), the author reports on his own 

 experiments with separated and kiUed young roots of wheat in a nutritive 

 medium. 



He states that the roots of vegetables adsorb and fix various forms of 

 mineral and organic nitrogen, this property being due apparently to the 

 presence of certain substiinces which are not removed by boiling water. The 

 power to adsorb different substances of the same molecular concentration 

 varies with the nature of these substances. It is stated also that for a given 

 form of nitrogen, conditions being equal, the quantity of nitrogen adsorbed is in 

 close relation to the concentration of the substance in the surrounding medium. 

 It is held that this faculty of adsorption may play an important part in the 

 appropriation of nutritive matter by plants. 



The absorption of different form.s of nitrogen by plants; influence of the 

 medium, D. Chouchak {Compt. Rend. Acad. Sci. [Paris], 156 {1913), No. 23, 

 pp. 1784-1787). — Continuing the above work, the author investigated the in- 

 fluence upon the adsorptive power exerted by living as well as dead roots of 

 wheat and their absorption of nitrogen on the addition of certain salts to the 

 ammonium chlorid nutritive medium. 



From these tests it is said that the other salts influence strongly both diffu- 

 sion into live plants and adsorption by dead ones. It appears also from 



