384 ANNALS NEW YORK ACADEMY OF SCIENCES 



suit of a very weak solution is simply a reversed resting potential, due 

 to the anion attachment to the pores of the membrane; the effect of a 

 stronger solution is a regular resting potential, due to reversible 

 loosening; while the result of a still stronger solution is an irreversible 

 disintegration, i.e., an injury potential. 



D. Inorganic Plurivalent Cations 



The occurrence of the well-known cation antagonism is another in- 

 dication of the prevalence of anionic colloids in cell structure. An im- 

 balance between the monovalent and the plurivalent cations shows up 

 in numerous observations upon animal and plant cells, among others 

 by alteration of their electrical properties, as, for example, ohmic 

 resistance, or conductance, or excitability. Preponderance of mono- 

 valent cations (sodium, potassium) is bound up in muscle and nerve 

 with loss of normal selective cation permeability, due to increased hy- 

 dration. However, this is compensated for by the consolidating effect 

 of plurivalent cations, like calcium, strontium, barium, cobalt, manga- 

 nese, nickel (Hober^). 



THE CHANGE OF ION PERMEABILITY BY DC 



Let us turn now to the old and complex phenomenon of electrotonus. 

 It comprises a multitude of alterations of cell responses, effected by 

 direct current and having their origin in changes of membrane polariza- 

 tion. Especially well-known are the changes of excitability of nerve 

 and muscle. Excitability is diminished at the anode and increased 

 at the cathode, except that, beyond a certain current strength, the in- 

 crease turns to a decrease, the so-called cathodic depression. Anelcc- 

 trotonus and catelectrotonus are tied up with changes of resistance. 

 By placing one electrode on an intact spot of the excised nerve, the 

 other on a crushed end, the resistance is raised at the anode, dimin- 

 ished at the cathode. Consequently, while sending alternating current 

 through the preparation instead of direct current, a rectifier effect ap- 

 pears. These and other observations can be explained, partly on the 

 basis of ion distribution between the inside and the outside of the 

 membranes, partly by taking again into account the colloidal prop- 

 erties of the wall of the natural membranes. As to the first point, ac- 

 cording to Bear and Schmitt,^ Cowan,^" Fenn and others," and Webb 

 and Young,^ the axoplasm of the giant nerve fiber of the squid, for 

 example, contains 4 to 5 times more inorganic cations (mainly potas- 

 sium) than anions, and 18 times more potassium than the blood. Be- 



