ON THE ELECTRICAL CHARGE OF PROTEIN. 151 



demonstrated without difficulty on the electrical properties 

 of the proteins. Every attempt to explain the phenomena 

 observed ends with the question, How does a protein 

 particle floating about, for example, in a dilute hydro- 

 chloric acid assume an electropositive charge when the 

 acid contains, as we know, an equal number of positive 

 H ions and negative Cl ions ? It is evident that this is only 

 possible when protein takes up more positive H ions than 

 negative Cl ions, or, as it is ordinarily stated, when the 

 protein is semi-permeable to ions. The same holds in 

 the case of alkalies for the OH ions. Many cells seem 

 to have this same power, and HOBER has rendered it 

 probable that red blood-corpuscles become positive when 

 treated with carbonic acid, because they become per- 

 meable for some of the negative ions which they contain 

 and which leave the red blood-corpuscles, thereby allowing 

 an excess of positive ions to remain behind. 



OSTWALD was no doubt the first to try to discover 

 in the semi-permeability for ions the cause of the electrical 

 phenomena observed in animal cells, and this suspicion 

 has recently attained a very considerable degree of proba- 

 bility. OKER-BLOM and later BERNSTEIN have further 

 developed this idea for the electrical phenomena observed 

 in muscle and nerve, and sought experimental evidence 

 for its support. If we imagine the surface of the muscle 

 fibril to be more permeable for the positive ions than for 

 the negative ions contained in the muscle, then the muscle 

 must carry a positive charge externally and a negative 

 one within. When two electrodes are laid upon the 

 surface of an uninjured muscle, points having a different 

 electrical potential are not touched, and the muscle 

 shows no current. 



