110 M. Dutrochefs Discoveries in Vegetable Physiology. 



across the separating membrane, completely prove the impo- 

 tence of the mathematical theory, by means of which M. Pois- 

 son believes that he has explained the phenomenon in question. 

 It remains to be determined if the affinity which may exist be- 

 tween heterogeneous fluids is the cause of the phenomenon. 

 This question is resolved by an experiment which I have men- 

 tioned in my work, and which I shall briefly relate here. If 

 the albumen of an egg is put into a large tube of glass, and if 

 pure water is cautiously poured from above, the two liquids 

 will not mix together ; we see distinctly the line of demarca- 

 tion which separates them. But this line of demarcation never 

 varies ; there is no increase in the bulk of the albumen, what- 

 ever length of time the experiment lasts. This proves beyond 

 contradiction that the albumen has no affinity to the water 

 which covers it. But when these two substances are separated 

 by a membrane, the water crosses it, to accumulate on the side 

 of the albumen, with which it then mixes. It is, therefore, to 

 some other cause than the reciprocal affinity of fluids to which 

 we must attribute this phenomenon. My opinion is that it is 

 caused by electricity, allowing, however, that this electricity 

 does not manifest itself in the galvanometer, of which I have 

 convinced myself by many trials. There are several ways to 

 conceive the formation of this electricity. I have been induced 

 to think that it may be caused by the approximation of the two 

 heterogeneous fluids, which are but imperfectly separated by 

 the permeable membrane which is interposed ; but then it ap- 

 pears to me that the two fluids ought to have a different elec- 

 tricity, which the galvanometer does not show. It appears to 

 me probable that this electricity is caused by the contact of the 

 fluids with the separating membrane. We know from the ex- 

 periments of M. Becquerel, that electricity is produced by the 

 contact of fluids with solid bodies. Thus, in the present cir- 

 cumstances, the contact of the two different liquids with the 

 two opposite sides of the separating membrane, produces two 

 different degrees of electricity, which are consequently stronger 

 on one side than on the other ; it is most likely this double 

 electrical action, which produces the two opposite and unequal 

 currents in intensity which cross the separating membrane. It 

 is certain that this phenomenon ceases to take place when the 



