M. Dutrochet's Discoveries in Vegetable Physiology. Ill 



two opposite sides of the separating membrane are in immediate 

 contact only with but one of the two different fluids, which is 

 shown in the following experiment. A tube of glass furnish- 

 ed with a wide mouth, which was closed with a plate of baked 

 pipe clay, about the twenty-fifth of an inch in thickness, was 

 filled with a solution of gum arabic, and then plunged in water, 

 above which the empty part of the tube rose vertically. The 

 endosmose took place, and the gummy fluid rose gradually in 

 the tube. Some hours afterwards the ascent of the fluid stop- 

 ped and it soon began to descend. Having taken the appara- 

 tus out of the water, I perceived that the plate of pipe clay 

 was coated on the outside with the gummy fluid driven from 

 within outwards by the exosmose. I wiped the outer surface 

 of this plate, and I replaced the apparatus, in the water ; im- 

 mediately the endosmose showed itself by the rise of the fluid 

 in the tube. Here the two opposite sides of the separating 

 membrane having ceased to be in immediate contact with the 

 different fluids, the phenomenon of endosmose ceased to take 

 place. It appears, then, that it is in this double contact that 

 the cause of the phenomenon is to be found. 



The double phenomenon of endosmose and exosmose being 

 produced by thin plates of inorganic bodies permeable to fluids, 

 as it is with the organic membranes, it follows that this phe- 

 nomenon is not exclusively an organic one, but that it is gene- 

 rally a phenomenon of general physics. This phenomenon, 

 however, is found to belong exclusively to organized bodies, 

 because it is only among them that we find different fluids se- 

 parated by thin and permeable membranes. This disposition 

 is never found in inorganic nature. Thus the double pheno- 

 menon of endosmose and exosmose is by the fact and not by its 

 nature a phenomenon entirely physical. It is the point at 

 which the physiology of living bodies is confounded with the 

 physiology of inorganic bodies. The more we advance in the 

 knowledge of physiology, the more reason we have for ceasing 

 to believe that the phenomena of life are essentially different 

 from physical phenomena ; this opinion, which the authority 

 of Bichat has above all others contributed to establish, is in- 

 dubitably erroneous. ,, 



