110 



ENDOSMOSIS. 



greater ease and more rapidity than pure water. 

 This may be added to the facts set forth already 

 to prove, in the most decided manner, that the 

 greater power of permeation manifested by one 

 of the two fluids in experiments on endosmosis 

 does not follow from any greater viscidity it 

 may possess than the fluid opposed to it. In 

 sixteen parts of water I dissolved two parts of 

 sugar and one part of oxalic acid. In this so- 

 lution I plunged the reservoir of an endosmo- 

 meter, closed with a piece of bladder, and filled 

 with pure water : this did not show any diffe- 

 rence of level in the tube during the two hoius 

 that I continued the experiment. There was 

 consequently no endosmosis. Nevertheless, I 

 found that the water contained in the endosmo- 

 meter contained a large quantity of oxalic acid, 

 whether tested by the addition of lime-water 

 or by the palate, which last also detected the 

 presence of sugar. Thus the sweet-sour fluid, 

 exterior to the endosmometer, had penetrated 

 the water contained within its cavity. If this 

 circumstance was proclaimed by no increase in 

 the volume of the water, this undoubtedly was 

 owing to the included water having lost by the 

 descending counter-current an amount exactly 

 equal to the amount it had gained by the in- 

 ward or ascending current. There was no en- 

 dosmosis in the sense in which I use that word, 

 although it is certain that there were two active 

 antagonist currents athwart the membrane which 

 separated the two fluids. It must not be lost 

 sight of that I only give the title of endosmosis 

 to a stronger current opposed to a weaker 

 counter-current , antagonists to each other, and 

 proceeding simultaneously athwart the septum, 

 dividing the two fluids which are made the 

 subjects of experiment. The instant these two 

 antagonist currents become equal, there is no 

 accumulation of fluid on one side, and there is 

 then no longer any effort at dilatation or im- 

 pulsion; in a word, there is no longer any 

 endosmosis. 



The opposite directions in which the endos- 

 mosis towards water, effected by acids of deter- 

 minate density, and the endosmosis from water 

 occasioned by other fluids, would lead us to 

 conclude that in placing such a fluid as gum- 

 water or sugar-water in an endosmometer fur- 

 nished with an animal membrane, and in con- 

 tact externally with an acid solution of appro- 

 priate density, we should have a much more 

 rapid endosmosis towards the included fluid 

 than if it were pure water in which the endos- 

 mometer was plunged ; and this in fact is what 

 I have found to be the case by experiment. 

 Into an endosmometer, closed with a piece of 

 bladder, I poured a solution of five parts of 

 sugar in twenty-four parts of water. Having 

 plunged the reservoir of the instrument into 

 water, I obtained in the course of an hour an 

 ascent of the included fluid, which may be re- 

 presented by the number 9. The reservoir of 

 the same endosmometer filled with a portion of 

 the same saccharine solution, having been 

 plunged into a solution of oxalic acid, the den- 

 sity of which was 1.014, (3.2 parts acid to 100 

 solution,) I obtained in the course of an hour 

 an ascent of the included fluid, which required 



to be represented by the number 27. The 

 substitution of a solution of oxalic acid for 

 pure water consequently caused the amount of 

 endosmosis in the same interval of time to be 

 tripled. I obtained like results with the tarta- 

 ric and citric acids, employed of the densities 

 required to enable them to produce endosmosis 

 towards water. From these experiments it 

 would appear that water, charged with a small 

 proportion of one of the acids, of which men- 

 tion has been made, possesses a power of pene- 

 tration athwart animal membranes greater than 

 that inherent in pure water. But a direct ex- 

 periment, detailed in an earlier part of this 

 paper, proves that this is not the case ; pure 

 water used by itself is still the fluid that pos- 

 sesses the greatest power of penetrating through 

 animal membranes. If, consequently, in those 

 experiments which I have last described, the 

 water charged with acid passed more readily 

 and more copiously into the saccharine solu- 

 tion than pure water, this happens undoubtedly 

 from other causes or conditions which I cannot 

 take upon me to explain, but which appear to 

 be : 1st. A reciprocal action between the two 

 heterogeneous fluids, an action which modifies, 

 which even completely inverts the natural 

 power of penetration possessed by each of the 

 fluids when employed singly ; 2d. A particular 

 action of the membrane upon the two fluids 

 which penetrate it, an action which, with the 

 animal membrane, gives the stronger current 

 or current of endosmosis to the acid solution of 

 due density, and the weaker current or coun- 

 ter-current of exosmosis to the pure water. It 

 seems to me impossible to deny this peculiar 

 action to the animal membrane, when we see 

 that a vegetable membrane in the same circum- 

 stances produces endosmotic phenomena di- 

 rectly the reverse. The peculiar influence of 

 the membranous septum is likewise manifested 

 in a very striking way in the experiment in 

 which I have shown that the current of endos- 

 mosis flows from water towards alcohol when 

 these two fluids are divided by an animal 

 membrane, and, on the contrary, that the cur- 

 rent of endosmosis flows from alcohol towards 

 water when the two fluids are separated by a 

 membranous septum of caoutchouc. 



Endosmosis, in the present order of things, 

 is a phenomenon restricted to the realm of or- 

 ganization ; it is nowhere observed in the inor- 

 ganic world. It is in fact only among organ- 

 ized beings that we observe fluids of different 

 density separated by thin septa and capillary 

 pores ; we meet with nothing of the same kind 

 among inorganic bodies. Endosmosis, then, 

 is a physical phenomenon inherent exclusively 

 in organic bodies, and observation teaches us 

 that this phenomenon plays a part of the high- 

 est importance in their economy. It is among 

 vegetables especially that the importance of the 

 phenomenon strikes us; I have, in fact, de- 

 monstrated that it is to endosmosis that are 

 due, in great part, the motions of the sap, and 

 particularly its very energetic ascending motion. 

 I have also shown that all the spontaneous mo- 

 tions of vegetables are referable to endosmosis. 

 The organic vegetable tissue is composed of a 



