JACQUES LOEB 57 



teric electrolytes in general stain with acid dyes in an acid but not in an 

 alkali solution, and with basic dyes only in an alkaline solution. This 

 agrees with our theory that an amphoteric electrolyte like gelatin can 

 exist as an anion capable of combining with a basic dye (e.g. neutral 

 red) only on the basic side of its isoelectric point, and that gelatin 

 can exist as a cation capable of combining with acid dyes (e.g. acid 

 fuchsin) only on the acid side of its isoelectric point. Our theory 

 further demands that gelatin when stained with neutral red should 

 give off its dye in solutions on the acid side of its isoelectric point, 

 since on this side of the isoelectric point gelatin can no longer exist as 

 an anion, while gelatin stained with acid fuchsin should give off its 

 dye in solutions with a pH >4.7, since here the gelatin can no longer 

 exist as a cation. All this turns out as our theory demands. The 

 writer intends to make further experiments on this problem, but the 

 facts thus far observed support our theory that when dissociating 

 electrolytically an amphoteric electrolyte is stable as an anion only 

 on the basic side of its isoelectric point, and as cation on the acid side 

 of its isoelectric point. Of course, in a non-ionized condition gelatin 

 may exist at any pH. 



Another apparent support of our theory lies in the old observation 

 made by Hamburger^^ on the absorption of CI and SO4 by the red 

 blood corpuscles from serum when the CO2 of the blood rises. In this 

 case it is probably simply a question of raising the pH of the blood 

 above that of the isoelectric point for hemoglobin, which is near the 

 point of neutrality. The whole problem of the retention and excre- 

 tion of electrolytes by the body may become intelligible from the fact 

 proved in this paper that proteins or amphoteric electrolytes in general 

 can exist as cations only (and have a tendency to become cations) 

 on the more acid side of the isoelectric point, while they can exist as 

 anions only (and have a tendency to become anions) on the less acid 

 side of their isoelectric point. 



11 Hamburger, H. J., and van Lier, G. A., Arch. Physiol., 1902, 492. Ham- 

 burger, Biochem. Z., 1918, Ixxxvi, 309. See also, Hasselbalch, K. A., and 

 Warburg, E. J., ihid., 1918, Ixxxvi, 410. 



