484: ABSORPTION. 



It undergoes modifications which can at present only be 

 explained on the supposition that the liquids become, for 

 the time, part of the living organic structures and partake 

 of their peculiar properties ; one of them, the property 

 by virtue of which they appropriate both the 'organic and 

 Ithe inorganic principles necessary to their proper consti- 

 tution and regeneration, is called by some, vital ; a word 

 which simply expresses ignorance of its essential character. 

 It must be understood, however, that this remark does not 

 apply to the general phenomena of endosmosis or absorp- 

 tion, but only to certain of its unexplained modifications. 



A most important property of organic tissues, which is 

 ignored by those who explain absorption on the principle of 

 capillary attraction, is that of hygrometricity. All the or- 

 ganic nitrogenized proximate principles are capable of losing 

 their water of composition by desiccation and of regaining it 

 by imbibition. The water w^hich enters into their composi- 

 tion is not necessarily contained in interstices in the tissue, 

 but, in the case of structureless parts especially, is uniform- 

 ly disseminated, or we may term it diffused, throughout 

 the organic substance, of which it forms a constituent part. 

 This action of certain liquids upon the organic semisolids is 

 something like the diffusion of liquids ; the difference being 

 that it is the liquid only which is diffused in the semisolid, 

 the semisolid being incapable of diffusing in the liquid. 1 As 

 it has been found that all liquids are not equally subject to 

 capillary attraction, so animal tissues imbibe different liquids 

 with different degrees of activity ; 2 a fact which will ac- 

 count in a measure for the variations in the endosmotic 

 currents with different solutions. 



Examples are not wanting of endosmosis by imbibition 

 or diffusion, when it cannot be assumed that there is any 



1 The liquid organic principles, such as albumen and caseine, are capable of 

 diffusing with other liquids, but the cohesion of membranes is too powerful to 

 allow of this reciprocal action. 



2 See pnge 470. 



