CHAPTER III 



IMBIBITION AND MOLECULAR STRUCTURE 



SECTION 12. The Force of Imbibition, and the Swelling of 

 Organized Bodies. 



IN order that the different vital processes which characterize the 

 living organism may be maintained, water and dissolved substances must 

 penetrate every part of the cell. The cell-wall, protoplasm, and indeed 

 all organized substances have the power of imbibing water and swelling. 

 This imbibed water causes the component particles of organized structures 

 to separate more or less widely from one another and thus brings about an 

 increase in volume of the whole, while the reverse change takes place when 

 the water evaporates. This property is not restricted to organized sub- 

 stances only 1 : thus gelatine and agar swell in water, collodion swells in 

 ether, and indiarubber in bisulphide of carbon. When the particles of 

 a solid become so widely separated that they pass beyond the spheres 

 of their respective attractive affinities, a condition resembling that of 

 solution is produced, and the organized structure is lost, if any were 

 originally present. It is preferable to restrict the term ' organized ' to 

 substances formed by the living organism, and not to apply it to all 

 bodies capable of imbibition and swelling, as was formerly done in con- 

 nexion with Nageli's theory 2 . 



Since all hypotheses concerning the molecular structure of organized 

 bodies are primarily dependent upon the phenomena of imbibition and 

 swelling which these exhibit, a general account of the phenomena in 

 question will be useful, especially as in physical text-books the points of 

 physiological importance are not brought prominently forward. From 



1 Viz. Acrylcolloid, Tollens, Ann. d. Chemie u. Pharmacia, 1874, Bd. CLXXI, p. 356. For other 

 examples see Pickering, Centralbl. f. Physiol., 1895, Bd. IX, p. 599. The formation of cellulose by 

 chemical synthesis is only a question of time. On the swelling of sphaerocrystals, A. Meyer, Starke- 

 kbrner, 1895, p. 108. 



' I. Aufl., Bd. i, p. 13. See Pfeffer, Studien zur Energetik, 1893, p. 158. 



