8 THE ROYAL SOCIETY OF CANADA 



vidual cells, but in their relationships one with another. The indi- 

 vidual cell on the one hand gives up substances to the tissue fluid in 

 which it lies; it is constantly absorbing material from the outside. 

 Enzyme action, which brings about a destructive disintegration of 

 the substances on which it acts, when carried far enough, may, on 

 occasion, be replaced by a synthesis of the very elements which it has 

 produced; if carried too far, may be neutralized by the production 

 elsewhere of antagonistic substances. While there is this struggle 

 after an equilibrium, it must be said that a state of absolute chemical 

 quiescence never is quite reached. The constant movement of molecules 

 is characteristic of what we call life. Only in dead tissue is there 

 complete equilibrium, in other words, perfect satisfaction of the various 

 affinities, to be found. In the language of the chemist, life may be 

 defined as a "state of persistent and incomplete recurrent satisfaction 

 and dissatisfaction of certain proteid or proteidogenous molecules." 

 It is important to get a clear idea as to how these chemical com- 

 binations are brought about. Of late, our conceptions of the 

 process have undergone a radical change. If, for example, a salt 

 like sodium chloride be placed in water, simple solution does not occur, 

 as we used to think, but a certain number of the molecules of the salt 

 are dissociated into their constituents (in this case Na and CI) , charged 

 some with positive, some with negative electricity. These are termed 

 ions — anions and kathions respectively. Free ions thus charged act 

 like independent molecules and are ready to be attracted by and unite 

 with other ions having an opposite charge. It is these dissociated 

 molecules that are active in chemical processes. Stable chemical 

 compounds are found by the union of ions possessing opposite electrical 

 properties. Now these combinations may be broken up two ways, 

 either by heat or electricity, in other words, agents which b}^ violent 

 means can dissociate the ions, or by solution. A sufficient amount of 

 water will serve to bring about the dissolution of all the molecules of 

 a salt. It is the liberated ions and not the compounds themselves 

 that enter in I'cactions one with another. This indicates the im- 

 portance of water to the cell. The human body as a whole is esti- 

 mated to consist of about 60% of water. It is thereby possible for 

 matter to be assimilated by the cells in a state of solution, and there- 

 by also the disintegration, rearrangement and combination of ions, 

 which are essential to growth and metabolism, become possible with- 

 out the liljcration by economy of an inordinate amount of energy in 

 the form of heat. It will be noted, also, that under this conception 

 metabolic processes are associated with the production of electrical 

 charges and discharges. This question of ionization also has an im- 

 portant practical bearing on therapeutics. Electrolytic substances, 



