April, 1920] PHYSIOLOGY 1.78 



PHYSIOLOGY 



B. M. Dugqar, Editor 

 GENERAL 



1202. Wakbman, Nellie. Teaching plant chemistry. Jour. Amer. Ph&rm. Assoc. 8: 

 105-108. 1919.— See Bot. Absts. 3, Entry 922. 



DIFFUSION, PERMEABILITY 



1203. Loeb, Jacques. The influence of electrolytes on the electrification and the rate of 

 diffusion of water through collodion membranes. Jour. Gen. Physiol. 1: 717-71.". 1919.— 

 The author's experiments indicate that the diffusion of water through a collodion membrane 

 depends on two kinds of forces, namely, first, those of gas pressure, and second, electrical 

 forces. Solutions of neutral salts possessing a univalent or bivalent cation influence the rate 

 of diffusion of water through a collodion membrane as if the water particles were charged 

 positively. The attractive and repulsive action increases with the number of charges of the 

 ion and diminishes inversely with a quantity the author designates arbitrarily as the "radius" 

 of the ion. The same rule applies to solutions of alkalies. "Solutions of neutral or acid salts 

 possessing a trivalent or tetravalent cation influence the rate of diffusion of water through a 

 collodion membrane as if the particles of water were charged negatively." Solutions of acids 

 obey the same rule, the high electrostatic effect of the hydrogen ion being probably due to 

 its small "ionic radius." — J. M. Brannon . 



1204. Loeb, Jacques. Amphoteric colloids. IV. The influence of the valency of cations 

 upon the physical properties of gelatin. Jour. Gen. Physiol. 1: 483-504. 1919.— A method of 

 preparing metal gelatinates is indicated. The author finds that the osmotic pressure of a 

 one per cent solution of gelatinates with univalent cations is almost exactly three times as 

 great at the same Ph as that of gelatinates with bivalent metals. The conductivities of the 

 solutions of the two types of gelatin differ little or not at all. From experimental evidence 

 given the author concludes that the proximity of the conductivities of metal gelatinates with 

 univalent and bivalent metal excludes the possibility that the differences observed in osmotic 

 pressure, viscosity, and swelling between metal gelatinates with univalent and bivalent metal 

 are determined by differences in the degree of ionization. An explanation is offered, based 

 on the hypothesis that aggregates of gelatin anions are formed with a single negative charge. 

 — J. M. Brannon. 



1205. Loeb, Jacques. Amphoteric colloids. V. The influence of the valency of anions 

 upon the physical properties of gelatin. Jour. Gen. Physiol. 1: 559-5S0. 1919.— The ratio of 

 maximal osmotic pressure of a one per cent solution of gelatin sulfate and gelatine bromide is 

 about 3 : 8. This same ratio was found for the ratio of maximal osmotic pressure of calcium 

 and sodium gelatinate. It was found that twice as many molecules of HBr as of HjSO« com- 

 bined with a given mass of gelatin. It is also shown in this paper that the same number of 

 molecules of phosphoric, citric, oxalic, tartaric, and succinic acids as of HNOjor HC1 combines 

 with the same mass of gelatin. Gelatin sulfate and gelatin bromide solutions of the same Ph 

 have practically the same conductivity. This, the author thinks, disproves the assumption 

 of colloid chemists that the difference in the effect of bromides and sulfates on the physical 

 properties of gelatin is due to a different ionizing and hydrating effect of the two acids upon 

 the protein molecule. — J. M. Brannon. 



1206. Osterhout, W. J. V. A comparison of permeability in plant and animal cells. 

 Jour. Gen. Physiol. 1: 409-413. 1919.— A striking agreement is shown between frog skin and 

 plant tissues in respect to certain aspects of permeability, antagonism, injury, recovery, and 

 death. — J. M. Brannon. 



