284 ABSORPTION. LCHAP.XXVI. 



shown by Chevreul, that an animal tissue imbibed very different 

 amounts of different fluids with which it was brought into contact 

 after it had been dried. Thus the cornea took up water, brine and 

 oil, in the proportions of 461, 370, and 9; and Liebig, in experi- 

 ments with the dried bladder of the ox and pig, has found, that "of 

 all liquids, pure water is taken up in the largest quantity ; that 

 the absorptive power for solution of salt diminishes in a certain 

 ratio as the proportion of salt increases; and that a mixture of 

 alcohol and water is taken up more abundantly the less alcohol 

 it contains/' * 



The mixture of two dissimilar fluids through a membrane is 

 much influenced by their respective attractions for the membrane. 

 Thus, as water has a stronger affinity for the membrane than brine 

 or alcohol, it permeates it more readily, and arrives in greater 

 quantity, in a given time, on the opposite surface than either of those 

 fluids. Hence, more water comes through to mix with the alcohol, 

 than alcohol to mix with the water, and an accumulation of the 

 mixed fluids consequently takes place on the side of the alcohol ; 

 for the alcohol, or the water, having once traversed the thickness of 

 the membrane, comes into contact with the opposite fluid, and 

 becomes diffused through it in obedience to known laws. The 

 same is true in regard to various substances miscible with water, 

 or dissolved in it. 



Within the blood-vessels and the lymphatics, is a fluid con- 

 siderably denser than water, and having less affinity for the walls 

 than water. Hence, if water be applied to the surface of the 

 body, or taken into the stomach, it readily enters the circulation, 

 particularly in the latter case, where it is brought into much closer 

 contact with the blood-vessels. If a quart of warm water be in- 

 jected into a torpid colon, half an hour will almost suffice to convey 

 it into the blood vessels, and thence through the kidneys into the 

 bladder. If, however, the injected water hold a considerable 

 quantity of common salt in solution, it will be absorbed more 

 slowly ; while, if the solution be a concentrated one, the fluid 

 portion of the blood will pass out of the vessels to mix with the 

 saline solution. The action of many medicines taken by the 

 mouth, particularly of saline purgatives, is in some measure 

 explained by these laws. 



It is interesting to notice that albumen passes less readily through 

 an animal membrane than gelatine, gum, or sugar. Thus, alcohol, 



* Researches on the Motion of the Juice in the Animal Body. Translated 

 by Wm. Gregory, M.D. London : 1848. P. 9. 



