BIOLOGICAL APPLICATIONS 211 



and regenerating the free protein to again participate in carrying 

 the current both ways. Provided, therefore, the two ions are 

 of nearly equal weight (and we have seen that in the case of the 

 ions of potassium caseinate the ions are nearly equal in weight, 

 of. previous chapter) no noticeable change in the distribution 

 of the protein in the electric field will be observed. If the ions 

 should be of unequal weight, then a trace of acid or alkali com- 

 bined with the protein might suffice to neutralize this inequality 

 and render the protein apparently "isoelectric." The "iso- 

 electric" protein of Michaelis is, therefore, in all probability, 

 merely free protein uncombined with acids or bases. This view 

 of Michaelis' result is supported by Pauli and Wagner (50) who 

 point out that the egg-albumin employed by Michaelis is, in 

 reality, an albuminate of a base, which therefore requires the 

 addition of some acid to set the protein free. The free protein 

 is sparingly ionized and hence the viscosity of its solution is low. 



5. Biological Applications ; the Neutrality of the Tissues and 

 of the Tissue Fluids. — The power which the protein salts 

 possess of neutralizing additional equivalents of acid or base by 

 the opening up of fresh — N.HOC— bonds confers upon them, 

 since the reaction of free protein is usually nearly neutral, a 

 remarkable power of maintaining the neutrality of their solu- 

 tions, and it appears probable that this characteristic of the 

 protein salts plays an important part in maintaining the neu- 

 trality of the tissues and a not insignificant part in maintaining 

 the neutrality of the tissue fluids. 



The older statements which are found in physiological and 

 medical literature concerning the reactions of the blood are totally 

 unreliable, since they were based upon the erroneous belief that 

 it is possible to ascertain the reaction of a fluid such as the blood 

 by titration. The determinations of Hoeber (31), Farkas (10) 

 (11) (12) (13), Fraenkel (18), Szily (69) (70), Hasselbalch (23) 

 (24) and de Corral (8) carried out by the potentiometric method, 

 have shown that the H+ and OH' ion concentrations of normal 

 blood are very close to those at neutrality (neutral point = 

 8 X 10~* H+ and OH'), the alkalinity first found by Hoeber having 

 been traced to the fact that the stream of hydrogen, used to 

 impregnate the platinum electrode of the gas-chain, washed the 

 CO2 out of the blood. On eliminating this source of error the 

 blood is found to be almost absolutely neutral, the exact OH' 



