LECT. III. EEL SKINS. 55 



millimetres ; but reached only 20 millimetres when the se- 

 cond arrangement was resorted to. 



With albuminous solutions the elevation was 26 milli- 

 metres when the external surface of the skin was in contact 

 with it, and 13 millimetres when placed in the contrary 

 direction. 



Skin of the Frog. The results obtained with the skin of 

 the frog, agree in general with those furnished by the skin 

 of the torpedo. We remarked that the direction of the en- 

 dosmotic current was constant, and was from the water to 

 solution of sugar, or of gum, or of albumen. We observed 

 that the membrane possessed the property of rendering en- 

 dosmose more or less intense, according to its position rela- 

 tively to the two liquids. In arranging the skin of the frog 

 in the two endosmometers in the usual manner, we obtained 

 an elevation of 36 millimetres when the external surface 

 was in contact with the solution of sugar, and of 24 milli- 

 metres in the reverse arrangement. In several cases the 

 former was exactly double the latter. There was likewise 

 a very marked difference, and always of the same kind, 

 when we used solutions of albumen and of gum Arabic. 

 With the first there was an elevation of 24 millimetres, 

 with the second 32 millimetres, when the external surface 

 of the skin was in contact with them ; whilst there was only 

 12 millimetres for a solution of albumen, and 16 millimetres 

 for a solution of gum, when the internal surface was turned 

 towards them. 



Eel Skins. The differences which We have already re- 

 marked from using a solution of sugar and skins of frogs 

 and the torpedo, exist equally in the case of the eel skin. 

 But what is singular with the latter is, that the difference is 

 not manifested at the commencement of the experiment. 

 At first the elevation of the liquid is alike in both instru- 

 ments ; but after a lapse of two hours we perceive that, in 



