ACTION OF INORGANIC TISSUES. 63 



tion originate in electrical excitement. The fact that electricity has, therefore, an en- 

 tire control over the motions of fluids in capillary tubes, will not be at all surprising. 

 This leads us to a generic resemblance between the phenomena of chemical affinity and 

 those of capillarity, which deserves a much more detailed investigation. Treatises on 

 chemistry represent a number of disturbing agencies which frequently antagonize, and 

 often control the operations of affinity ; these are cohesion, elasticity, quantity of mat- 

 ter, gravity, and the agency of the imponderables. It is, however, a mistake to enumer- 

 ate either quantity of matter or gravity as ever disturbing the action of affinity. Grav- 

 ity, it is true, mav cause the lower parts of a solution or an alloy to be denser than the 

 upper : but an action of this kind is not to be accounted as an example of contrariety 

 in the forces. It does not exhibit them at all at variance with each other, or in any 

 manner neutralizing each other. Similar remarks might be made in respect to quantity 

 of matter. The elastic state, being merely a condition of cohesion, influences the ac- 

 tion of affinity by presenting bodies under a modified form as respects their cohesion. 

 Strictly speaking, there are but two forces which in reality control affinity ; these are 

 cohesion and the agency of the imponderables. And these are the forces that control 

 capillarv action, the phenomena of which are the results of the equilibrium of an attrac- 

 tive force on the one hand, and cohesion on the other. They may be regarded as 

 modified cases of chemical affinity, and, being brought about by the operation of the 

 same forces, are under the control of the same disturbing agents. 



204. In (195) I have enumerated different cases of ineffectual attempts to recognise 

 the action of endosmosis in inorganic bodies. I have also shown the peculiar disturbance 

 that arises when interstitial communication is too free, and the relation that must exist 

 between a solid and a fluid for molecular transudation to happen. Now, when all these 

 conditions are fulfilled in any barrier, the phenomena of endosmosis will take place ir- 

 respective of its nature, whether it be organic or inorganic. Plates of kaolin or porce- 

 lain clav from Villarica, disks of steatite from Brazil, after undergoing induration in the 

 fire, and a variety of compact sandstone being cemented on the end of a tube, exhibited 

 in a verv satisfactory manner the passage of water into gum-water, even against hy- 

 drostatic pressures of several inches. Independent of this decisive evidence, it might 

 be determined that an organized tissue is not essential to this process, from the circum- 

 stance that common writing paper, fastened with sealing wax on the end of an open 

 tube, exhibits the endosmosis of water into gum-water in a much more striking manner 

 than bladder ; and certain inspissated juices of plants as caoutchouc, when in thin lay- 

 ers, act very well, though not so rapidly. Of all substances hitherto tried, filtering pa- 

 per, imbued with coagulated albumen, acts most satisfactorily. 



20-5. A repetition of these experiments, made under a variety of circumstances, leaves 

 no farther doubt as to the true character of Dutrochet's endosmosis. It is not, as some 

 would have us suppose, a vital or a semi-vital force; it is nothing more than a peculiar 

 case of capillary action. 



206. The conditions which this peculiar case requires are, that both the fluids shall 

 be able to wet the barrier, that in a capillary tube formed of it they should rise to dif- 

 ferent heights, and that they should be able to unite chemically with each other. If we 



