CALVIN B. COULTER 323 



3. On the alkaline side at least the charge carried by sensitized cells 

 is smaller and increases less rapidly with the alkalinity than the 

 charge of normal cells. 



4. Both normal and sensitized cells combine chemically with inor- 

 ganic ions, and the isoelectric point is a turning point for this chemical 

 behavior. On the acid side the cells combine with the hydrogen and 

 chlorine ions, and in much larger amount than on the alkaline side; 

 on the alkaline side the cells combine with a cation (Ba), and in 

 larger amount than on the acid side. This behavior corresponds with 

 that found by Loeb for gelatin. 



5. The optimum for agglutination of normal cells is at pH 4.75, so 

 that at this point the cells exist most nearly pure, or least combined 

 with anion and cation. 



6. The optimum for agglutination of sensitized cells is at pH 5.3. 

 This point is probably connected with the optimum for flocculation 

 of the immune serum body. 



The author wishes to express his indebtedness to Dr. K. George 

 Falk, of the Harriman Research Laboratory, the Roosevelt Hospital, 

 New York, for criticism and suggestions. 



