320 ISOELECTRIC POINT OF RED BLOOD CELLS 



A similar determination was made on the combination with a cation 

 at different pH values. Cells were suspended in isotonic BaCh, then 

 washed, and again suspended in saccharose solution which had been 

 brought to pH 6.0 with Ba(0H)2 instead of NaOH. The amount of 

 Ba present was therefore small, and could only be estimated from the 

 turbidity of the fluid on adding Na2S04. Many of the experiments 

 showed no significant differences; in several, however, it was found 

 that the amount of Ba in the supernatant fluid increased sharply at 

 pH 4.7 and showed a further increase to pH 4.0. This must mean 

 that the Ba was liberated from combination with the cells on the acid 

 side of the isoelectric point. 



Exactly the same chemical behavior has been found by Loeb^ for 

 gelatin, which combines with cation only on the alkaline side of its 

 isoelectric point and with anion only on the acid side. This Loeb 

 has shown by a series of volumetric analyses for Ag, Br, and CNS 

 ions of the gelatin-ion compound. This work was unfamiliar to the 

 present author at the time the observations detailed above were car- 

 ried out. It is significant of the general importance of this relation 

 that the same chemical behavior is manifested both by solutions of 

 gelatin and by living cells. The old observation of Hamburger^* 

 that under the influence of HCl, H2SO4, or CO2 red cells take up chlor- 

 ine from the serum, while on the addition of alkali they give chlorine 

 "up to the serum, is thus to be interpreted, as suggested by Loeb, by 

 the difference in chemical combining power on either side of the 

 isoelectric point. 



The conclusion appears justified by these facts that the character of 

 the charge carried by a red cell depends upon the nature of its chemi- 

 cal combination; and that the amount of charge depends upon the 

 amount of protein in ionic combination. This conclusion was facili- 

 tated by the observations of Loeb, alread}'^ referred to. 



The curve for velocities of normal cells (Fig. 2) on the alkaline side 

 of the isoelectric point closely parallels the curve given by Loeb for 

 swelling and conductivity of Na gelatin. Koranyi and Bence^^ have 

 shown that between saturation of defibrinated blood with CO2 on the 



^^ Hamburger, H. T., Osmotischer Druck und lonenlehre, Wiesbaden, 1902, i. 

 ^^ Koranyi, A., and Bence, J., A)-ch. ges. Physiol., 1905, ex, 513. 



