OF VITAL PHENOMENA 131 



astonishment. Hamburger (1908) found this valvelike action 

 to be shown (in a very much smaller degree) by dead intestinal 

 wall and by double membranes made by pasting together two 

 membranes of different material. These results remind us of 

 the theory of Flusin (1908 a) that osmose is controlled by three 

 factors : 



1. The attraction of the membrane for the solvent, determining 

 its imbibition. 



2. The presence of solutes affecting this imbibition. 



3. The mutual attraction between solute and solvent. 



This third factor is the principal one according to Traube, 

 who calls it "haftdruck." Assuming 2 and 3 to remain con- 

 stant, osmose is affected by imbibition of the membrane, and if 

 imbibition is different on the two sides the osmose might be 

 forced in one direction or the other. This seems to be the view 

 of H. N. Morse as a result of his direct determination of osmotic 

 pressure. Osmose is then the resultant of three processes, be- 

 tween the first solution and the membrane, between the two sides 

 of , the membrane, and between the membrane and the second 

 solution. 



It seems evident that one effect of imbibition is to alter the 

 size of the pores, and Bartell has shown that the enlargement 

 of the pores can change positive into negative osmose. Electro- 

 endosmose seems to be at least one factor in the valvelike action 

 of living membranes. Girard (1910) observed that the valvelike 

 action of frog's skin separating isotonic salt from sugar solution, 

 ceased when the skin current was inhibited by anesthetics. 



Assuming that living membranes are easily permeable to H 

 ions, the more acid of two solutions separated by the membrane 

 should be electronegative, and the osmose should be toward it, 

 since electroendosmose is usually toward the negative pole. This 

 view is in harmony with the fact that osmose is from the alkaline 

 blood to the acid stomach and kidney cavities, but from the alka- 

 line intestine to the slightly less alkaline blood. It is probable 

 that protoplasm is less alkaline than blood, hence the turgidity 

 of cells. 



Bernstein in his "Elektrobiologie" accords first place to electro- 

 endosmose in explaining osmose through living membranes. The 

 electric polarization of such membranes is reduced or disappears 



