154 THE MECHANISM OF LIFE 



but little of the transformation of energy which takes place in 

 an osmotic production, hut we may say with certainty that it 

 is capable of transforming both chemical energy and osmotic' 

 energy into heat and mechanical motion. 



An osmotic production is the arena of complicated chemical 

 phenomena which produce a veritable metabolism. It has 

 long been known that diffusion and osmosis may determine 

 various chemical transformations. II. St. Clair Deville has 

 demonstrated that certain unstable salts are partially 

 decomposed bv diffusion. Thus during the diffusion of alum. 

 the sulphate of potash is separated from the sulphate of 

 aluminium. Similarly, when the chloride or acetate of 

 aluminium is caused to diffuse, the acids become separated 

 from the ahnninia. This decomposition is the result of the 

 different resistance which the medium offers to the diffusion 

 of different ions. This difference of resistance may even cause 

 a difference of potential between two media, similar to the 

 differences of potential in living organisms. Frequently also 

 a difference of hydration in the chemical substances 0:1 

 either side of an osmotic membrane will determine a chemical 

 reaction, which like all oilier chemical reactions is accompanied 

 by a corresponding transformation of energy. The study of 

 these chemical metamorphoses and the transformations of 

 energy in osmotic growths has opened up a new subject for 

 experimental investigation in the field of organic chemistry. 



Coag'ulation. — There is a most remarkable analogy between 

 the phenomena of coagulation as seen in living beings and the 

 phenomena which occur when the liquid in the interior of an 

 osmotic growth comes into contact with the mother liquor. 

 When the sap of a plant or the blood of an animal escapes 

 into the air or water of the surrounding medium, it coagulates. 

 i.e. it changes from a liquid to a gelatinous consistency. In 

 the same way, when the liquid in the interior of an osmotic 

 growth leaks out into I he mother liquor it forms a gelatinous 

 precipitate. This gelatinous precipitation is a physico- 

 chemical phenomenon of the same nature as coagulation. It is 

 by the study of coagulation in liquids less complex than blood 

 that we may hope to elucidate the mechanism of the process, 



