310 ISOELECTRIC POINT OF RED BLOOD CELLS 



cation and moves to the cathode. Chemically, therefore, the protein 

 exists most nearly "pure," least combined with acid or alkali, at the 

 isoelectric point. It is the purpose of the present paper to show the 

 applicability of this conception of the physical and chemical signi- 

 ficance of the isoelectric point to the agglutination of red cell 

 suspensions. 



The literature pertaining to this subject may be reviewed briefly. 

 The movement of red blood cells in the electric field has been observed 

 by Lillie,^ by Girard-Mangin and Henri,^ and by others since. Hober^ 

 found that the original negative charge became positive on saturation 

 of the solution with CO2 in the presence of very small amounts of 

 electrolyte, but found that thechargewas not reversed if large amounts 

 of salt were present. This effect he referred to the acid character of the 

 CO2 introduced, and ascribed the reversal of charge to the permeability 

 of the cell wall to anions at the increased hydrogen ion concentration. 

 He noted that ferric and aluminium salts conferred a positive charge 

 upon the cells in all concentrations of NaCl in the solution. Mines* 

 found the red blood cells of Scyllium negatively charged in the serum. 

 On the addition of strong cerium chloride solution to a suspension of 

 cells the charge becomes uniformly positive and no agglutination 

 occurs; with dilute cerium solution the cells promptly agglutinate. 

 This Mines explains by assuming that in dilute cerium solution only 

 certain of the cells are affected ; these cells encounter others still nega- 

 tively charged and mutual neutralization results, with precipitation of 

 the neutralized cells. 



Electric transport of bacteria has been carried out by many investi- 

 gators. Sears and Jameson,^ pupils of Zinsser, studied the migration 

 of bacteria at varying degrees of acidity and found that addition of 

 alkali increased their rate of movement while acid lessened it. The 

 fact that protein solutions flocculate most readily near their isoelectric 

 point has suggested that this may be the mechanism of bacterial 

 agglutination, but Beniasch'' in studying acid agglutination of bacteria 



2 Lillie, R. S., Am. J. Physiol, 1903, viii, 273. 



^ Girard-Mangin, and Henri, V., Compt. rend. Soc. Biol., 1904, Ivi, 866. 



*Hober, R., Arch. ges. Physiol., 1904, ci, 607; 1904, cii, 196. 



5 Mines, G. R., Kolloid Chem., 1911-12, iii, 191, 236. 



* Sears, H. J., and Jameson, E., Cataphoresis of Bacteria, San Francisco, 1912. 



^Beniasch, M., Z. Immunitatsforsch., Orig., 1911, xii, 268. 



