EDEMA 187 



intracellular acidity, compatible with the life of the cell, is far too limited 

 to induce colloids to swell. 



In view of the observations of Loeb(&)(1918) on the influence of the 

 hydrogen ion concentration on the various properties of colloids, including 

 swelling, it may be regarded as proved that the increased affinity of colloids 

 for water depends not on any increase in acid content, as such, but on 

 the actual hydrogen ion concentration of the medium in which the colloids 

 are suspended. There is no evidence to show- that edema is accompanied 

 by significant variations from the normal of hydrogen ion concentration 

 of normal blood plasma, and such analyses as are available (Frankel, Foa, 

 Bottazzi, Sb'rensen) indicate a very close approximation of the hydrogen 

 ion concentration of edema fluids to that of blood plasma. 



The theory of Eppinger that, under the influence of certain toxic sub- 

 stances in the blood in nephritis, the permeability of the capillary walls 

 is qualitatively changed to permit large colloid molecules to pass out from 

 the blood, has this point in common with Fischer, that both have postulated 

 a leakage of albumin from the capillaries into the tissues. While Fischer 

 bases the retention of water on the swelling of these colloids, due to an 

 increased production of acid, Eppinger suggests simply the retention of 

 fluid in the intercellular spaces by the increased osmotic pressure due 

 to the increased content of protein molecules. 



Electrostatic Pressure. The distribution of electrolytes is affected not 

 only by the diffusion pressure of their molecules and ions, but also by the 

 attractive force of oppositely charged ions. Any difference in electrical 

 potential which develops in different parts of a fluid is thus rapidly 

 brought to equilibrium by the migration of ions. Loeb(c) (1919) 

 has also shown that under certain conditions the molecules of water may 

 assume an electrical charge, and ' that the electrification of water, and 

 of the membrane itself, may influence to a considerable degree the move- 

 ment of fluid through membranes. In view of the differences in potential 

 known to occur in the tissues it seems extremely likely that such differences 

 may have a profound effect on the movement of the fluid. The possibility 

 of this effect and its bearing on physiological processes has not yet been 

 sufficiently considered from the experimental standpoint to permit the 

 statement of an opinion on its influence in the conditions under discussion, 

 but the subject has already received some consideration (Gunzburg). 



Influence of Chlorids and Fluids. The clinical effects of varying 

 intake of chlorids and fluids have been discussed. Although the mech- 

 anisms underlying these effects cannot be fully analyzed until the various 

 forces concerned in lymph formation and edema are more clearly under- 

 stood, certain considerations may be set forth on the basis of the analysis 

 of the forces just discussed. 



Cohnheim and Lichtheim found that they could inject physiological 

 salt solution into normal rabbits and dogs, up to 92 per cent of the body 



