72 ENDOSMOSE. LECT. III. 



position in which endosmose is most intense ; and the cases 

 are very rare in which, with fresh membrane, endosmose 

 takes place equally, whatever be the relative position of the 

 membrane to the two liquids. 



3dly. The direction which is most favourable to endos- 

 mose through the skins, is usually from the internal to the 

 external surface, with the exception of the skin of the frog, 

 in which endosmose, in the single case of water and alcohol, 

 is promoted from the external to the internal surface. 



4thly. The direction favourable to endosmose through 

 stomachs and urinary bladder varies, with different liquids, 

 much more than that through skins. 



5thly. The phenomenon of endosmose is intimately con- 

 nected with the physiological condition of the membranes. 



6thly. With membranes, dried or altered by putrefaction, 

 either we do not observe the usual difference arising from 

 the position of their surfaces, or endosmose no longer takes 

 place. 



Exosmose. To give an accurate account of the subject 

 of our experiments, and of the conclusions we have drawn 

 from them, it is necessary to consider exosmose in a point of 

 view different from that in which it has hitherto been re- 

 garded. The augmentation of volume presented by the 

 internal liquid, which is usually the denser one, is consi- 

 dered by Dutrochet as the result of a difference between 

 the in-going strong current and the out-going weak current. 

 According to this view, that liquid which receives from the 

 other one more than it gives, should increase in proportion 

 to the excess which it receives, or to the difference between 

 the strong current and the weak one. But all the facts 

 which we have observed, lead us to the conclusion that 

 different membranes allow the passage of water to the liquid 

 in the endosmometers more easily in one direction 4han in 

 another, and more readily with some liquids than with 



