318 THE EQUILIBRIUM OF COLLOID AND 



holders of the membrane theory, arise from greater solubility of the 

 anaesthetic in the membrane, because that would only delay the 

 arrival of the anaesthetic at the active part of the cell until the lipoid 

 membrane had first been saturated with anaesthetic. 



For this reason also greater solubility of any constituent in 

 the cell substance itself will not explain the greater amount of 

 concentration of any particular substance or ion in the process 

 of secretion or excretion. Such greater solubility would serve to 

 fill the cell up with it and keep it there, but would not hasten passage 

 through the cell, and after the solubility in the cell substance had 

 been satisfied, diffusion would then go on until the free concentra- 

 tion on the secretion side equalled the concentration on the lymph 

 side, but not a fraction beyond this point. 



With regard to increased or specific solubility in the cell sub- 

 stance as an agency in statically loading the cell up with a given 

 constituent or ion, as distinct from passing it out again in heightened 

 concentration in a secretion, it may be admitted that this would 

 explain the accumulation ; but this on closer examination is essen- 

 tially the same view as that of union or adsorption with the protein, 

 except that the adsorption or combination view goes a step farther 

 and attempts to give a basis for the increased or specific solubility. 



Even in the simpler case where a substance in solution divides 

 itself in different concentrations between two solvents which do 

 not mix with each other, 1 giving rise to the quotient of distribution, 

 it is obvious that there is an equilibrium between the concentrations 

 in the two media depending upon the relative affinities (or residual 

 affinities) of the molecules of two solvents respectively for the mole- 

 cules of the solute or dissolved substance. 



One may therefore quite justly assign the unequal distribution 

 of the various ions in cell and environing fluid respectively to 

 different solubilities in the two media; apart from membrane 

 action which is out of the question unless the somewhat absurd 

 hypothesis be made that the accumulation remains and resides in 

 the membrane. But knowing the nature of the constitution of the 

 protein constituents, and that these must possess residual affinities 

 or absorptive powers, it appears feasible to go a step farther and 

 assign the distribution and different solubility to the formation of 

 unions between protein or bioplasm and the ions. 



1 As, for example, an organic acid dividing itself between water and 

 ethylic ether. 



