TISSUES TO WATER. 6 



horny, hard, and translucent, now again become 

 flexible and elastic, and recover their silky lustre. 

 The fibrine and the cartilages of the ear, which 

 desiccation had rendered horny and transparent, 

 again become milk-white and elastic. 



The power which the solids of the animal body The tissues 



absorb 



possess of taking up water into their substance, and other flu- 

 of being penetrable to water, extends to all fluids 

 allied to water, that is, miscible with it. In the 

 dried state, the animal solids take up fluids of the 

 most diverse natures, such as fatty and volatile oils, 

 ether, bisulphuret of carbon, &c. This permeability 

 to fluids is possessed by animal tissues in common 

 with all porous bodies ; and no doubt can be enter- 

 tained, that this property is determined by the same 

 cause which produces the ascent of fluids in nar- 

 row tubes, or in the pores of a sponge ; phenomena, 

 which we are accustomed to include under the name 

 of capillary action. 



One condition, essential to the permeability of The moist- 

 porous bodies for fluids (or their power of ab- 



sorption), is their capability of being moistened ; or 

 the attraction which the particles of the fluid and 

 the walls of the pores or tubes have towards each 

 other. A second condition is the attraction which 

 one particle of the fluid has to another. We have 

 no means of estimating the absolute size of the par- 

 ticles or molecules of a fluid, such as water, but 

 they are certainly infinitely smaller than the 

 measurable diameter of a tube, or of the pores of 



B 2 



