482 ABSOKPTION. 



ful corresponding to the endosmoticj and the feebler to the 

 exosmotic current. This inequality in the currents is explain- 

 ed by the fact that porous substances imbibe different liquids 

 with different degrees of activity ; * so that the septum 

 always contains a greater quantity of one of the liquids. 

 It is the liquid thus introduced in greater quantity in 

 which the more powerful current is developed. In this case, 

 also, the difference in the diffusibility of the liquids has 

 an important influence ; but these phenomena will be more 

 fully considered when we come to treat of the influence of 

 different liquids upon endosmosis. 



Numerous experiments have demonstrated that both -the 

 endosmotic and the exosmotic current may be produced by 

 using a porous instead of a membranous septum, though 

 they are always more feeble. 2 The phenomena thus pre- 

 sented are to be explained entirely by the laws of capil- 

 lary attraction and of the diffusion of liquids. These laws 

 would enter largely into the explanation of the passage of 

 liquids through animal membranes, if it could be demon- 

 strated, or even rendered probable, that these membranes 

 are porous, or are provided with capillary openings. It will 

 be necessary, however, to study this question very carefully, 



1 This fact is strikingly illustrated in some of the experiments of Matteucci 

 on the imbibition of different solutions by tubes filled with fine sand (Lecons sur 

 les Phenomenes Physiques des Corps Vivants, Paris, 184*7, p. 21). 



2 DUTROCHET, De rjj/ndosmose. Memoires pour servzr d VHistoire Anato- 

 mique el Physiologique des Vegetaux et des Animaux, Paris, 1837, tome i., pp. 

 21-23. 



Dutroehet made a number of experiments with different porous septa. He 

 found it impossible to produce endosmosis through thin sections of sandstone 

 or of imperfectly baked porcelain ; but with a septum of potter's clay, one- 

 twenty-fifth of an inch thick, there was a tolerably energetic endosmotic current. 

 The same result followed when the septum was from one-twelfth to one-fifth of 

 an inch thick ; but in septa of greater thickness than this, the currents were 

 very feeble. These experiments were repeated by Graham with more satisfac- 

 tory results. By employing a porous jar, such as is used in Grove's battery, 

 vigorous endosmotic and exosmotic currents were produced. (On Osmotic Force* 

 Philosophical Transactions, London, 1854, p. 180.) 



