594 BLOOD SERUM AND EDEMA FLUID 



point depression of serum and of edema fluid is the same — 

 within the limit of error of the method when applied to physio- 

 logical solutions, (b) The conductivity of the edema fluid is 

 always higher than that of the blood, but the greater the protein 

 content of the edema fluid, the closer the conductivity approaches 

 that of the serum. This is in accord with experiments on pure 

 protein solutions, in which it was found that, at the pH of the body 

 fluids, the higher the protein content, the lower the conductivity.^ 



(c) The chloride content of the edema fluid is always higher than that 

 of the serum. (This is at variance with findings of Epstein.^) This 

 difference of CI concentration in blood and edema fluids diminishes, 

 in general, as the protein content of the edema fluid increases. 



(d) The concentration of potassium is greater in the serum than in 

 the edema fluid, (e) The concentrations of HCO3, Na, sugar, non- 

 protein nitrogen, and Ca and urea, where these were determined, are 

 approximately the same, in the determinations made thus far. 



The experiments on the dialysis of serum against edema fluid 

 reported in Table II, demonstrate that no new equilibrium is es- 

 tablished when the two fluids are separated by a simple collodion 

 membrane. The relatively high concentration of potassium inside 

 and the relatively high concentration of chlorine outside the membrane 

 are but slightly changed. The results suggest that these interesting 

 relationships depend on a simple membrane equilibrium and are not 

 entirely due to properties peculiar to living protoplasm. 



CONCLUSIONS. 



1. Comparative studies of blood serum and edema fluid from the 

 same individual indicate that, regardless of the pathological condition 

 present, whether the fluid be "transudate" or "exudate," certain 

 definite qualitative chemical relations obtain. 



2. The chief feature of these relations is that the edema fluid con- 

 tains more CI and less K than the blood serum ; while the Na, HCO3, 

 Ca, urea, glucose, and non-protein nitrogen exist in approximately 



1 Palmer, W. W., Atchley, D. W., and Loeb, R. F., J. Gen. Physiol., 

 1920-21, iii, 801; 1921-22, iv, 585. 

 * Epstein, A. A., J. Exp. Med., 1914, xx, 334. 



