54 ENDOSMOSE. LiECT. III. 



Class 1. Experiments with the Skins of the Frog, Tor- 

 pedo, and Eel. I shall first state the results obtained by 

 employing, as the membranes, the skins of frogs, torpe- 

 does, and eels, with the before-mentioned solutions for the 

 liquids. 



Influence of the Position of the Membrane. In our first 

 trial we noticed, in a very clear manner, the marked in- 

 fluence exercised upon the phenomenon of endosmose by 

 the position of the interposed membrane. It was in fact 

 this first discovery which led us to examine, in this point of 

 view, the effects produced by the bladder and stomach of 

 divers animals. With some trouble we obtained entire 

 skins, and deprived them of all adherent sub-cutaneous 

 cellular tissue. After having thus, prepared them, we cut 

 off those parts which, in the torpedo and eel, are perforated 

 by the cutaneous appendages, and so obtained membranes 

 well fitted for our experiments. 



Skin of the Torpedo. By employing the skin of the tor- 

 pedo, placed in one endosmometer with its external sur- 

 face towards the interior of the instrument, and in the other 

 reversely, and by filling the two endosmometers with a solu- 

 tion of gum Arabic, we observed that, whilst the liquid in 

 the first instrument rose 30 millimetres, it rose in the second 

 sometimes 18, and sometimes only 6 millimetres. In certain 

 cases we saw the liquid elevated 20 millimetres or more, in 

 the first tube, whilst it scarcely rose at all in the second. 



These differences are equally observed, with a solution 

 of sugar. Thus, this liquid which rises 30 and even 80 

 millimetres when the external surface of the skin is turned 

 towards the instrument where the liquid is contained, rises 

 at the utmost only 2 millimetres when the membrane is 

 placed in the contrary direction. In one case where the 

 first-named arrangement was adopted, the liquid rose 80 



