CRYSTALWIDS 25 



peiHlciif ly ot" a (•cUiilai' origin, which the proteins never do. Tlie inoi- 

 ganic salts in i)arti('iihir seoni (luilc i'oi-eifj;n to H\inji processes, and 

 as they enter and leave the body i)ractieally unchanged they are 

 evidently not a source of energy through chemical change. Their 

 importance to the cell lies almost entirely in their physical or physico- 

 cliemical properties. The organic crystalloids, although of nutri- 

 tional value, also have ])hysical jiropei-ties in some respects similar to 

 those of the inorganic crystalloids, and therefore to this extent they 

 exert similar influences, but the essential difference between the organic 

 and the inorganic crystalloids is that all the latter are electrolytes, 

 while many of the organic crystalloids that occur in cells are non- 

 electrolytes. The importance of this distinction lies not in the utility 

 or non-utility of these substances as conductors of electrical currents 

 in the ordinary sense, but rather on the existence of those properties 

 which determine their conductive al)ility. Electrical conductivity is 

 an index of ionization, and upon ionization depends the chief influence 

 of the electrolytes upon vital activities. The importance of this 

 process of dissociation or ionization lies in the fact that with most 

 substances no chemical reaction can occur while the substance is in the 

 non-ionized state. The chemical properties of ionizable substances 

 are produced largely by the ions they liberate on dissociation. As a 

 consequence, the physiological effects of electrolytes are due to their 

 ionic condition, and through the ions that are present in the cell many 

 of its various chemical processes are brought about. Not all substances 

 ionize with the same readiness, which causes a great difference in their 

 properties. The reason that acetic acid is a weaker acid than hydro- 

 chloric acid is that it does not ionize to such an extent, and so a cor- 

 responding ciuantity does not introduce as large a number of hydrogen 

 ions into a solution. Larger molecules, as a rule, ionize less than smal- 

 ler ones of similar nature, e. g., stearic acid ionizes less than acetic acid 

 and therefore is a weaker acid. Likewise the properties of a substance 

 which depend upon its ions will be less marked when it is in a solvent 

 that produces little ionization. For example, bichloride of mercury 

 owes its antiseptic properties to the Hg ions that it sets free when in 

 solution. It is well known that solutions of mercury, and for that 

 matter most other antiseptics, are much less actively germicidal in 

 alcohol than when in water, because their ionization is less in alcohol; 

 and the germicidal properties decrease as the proportion of alcohol 

 increases, until the germicidal effect of the mixture is no greater than 

 that of alcohol alone in the same strength. 



If we had no electrolytes in the cell, electric charges could not be 

 carried about in it, and hence chemical reactions could not occur. 

 It is this fact that makes the inorganic salts of such vital importance 

 to the cell life. To repeat Mann's words, it is the electrolytes that 

 put life into the proteins. Water itself is almost absolutely non-disso- 

 ciated, and proteins so little that for some time it was doubted if they 



