488 ABSORPTION. 



quids, by using different membranes. This fact was well illus- 

 trated in some of the experiments of Matteucci and Cinia, in 

 which comparative observations were made upon the currents 

 through the skin of the torpedo, the skin of the frog, and the 

 skin of the eel. The results obtained with these different 

 membranes showed marked and constant variations. The 

 same observers, in using the mucous membrane of the stom- 

 ach of the lamb, found a marked difference in the endosmot- 

 ic phenomena when the surface exposed to the water was 

 reversed. In two experiments, with the epithelial surface of 

 the membrane turned toward the interior of the endosmom- 

 eter, the elevation of the liquid in an hour and a quarter 

 was from forty-four to fifty-six millimeters; but with the 

 membrane reversed, so that the attached surface was turned 

 toward the interior, the elevations during the same period 

 were sixty-six and seventy-two millimeters. 1 This difference 

 is readily explained by the difference in the constitution of 

 the two surfaces of the membrane used. 



From these facts it is evident that while the diffusion of 

 liquids as they meet in the substance of a membrane is the 

 actual cause of the osmotic currents, which are continued as 

 the liquids diffuse with each other upon either side of the 

 membrane, the determination of a predominating or endos- 

 motic current, the ordinary conditions being undisturbed, is 

 effected by the greater attractive force which the membrane 

 exerts upon one of the liquids. 



Influence of Different Liquids upon Osmotic Currents. 



The action of the liquids between which endosmotic cur- 

 rents take place is, as we have seen, most intimately con- 

 nected with the force by which the liquids enter the mem- 

 brane, be it capillary attraction or imbibition ; but the at- 

 tractive force exerted by the membrane is never capable, in 

 itself, of producing a current. It is evident, therefore, that 



1 MATTEUCCI, Lemons sur les Phenomenes Physiques des Corps Vivants^P&ris, 

 1847, pp. 48, 51. 



