STRUCTURE OF PROTOPLASM OF PARAMCECIUM. 21 



identical with the structural changes produced by the action of 

 electrolytes upon the protoplasm. About the anode and on the 

 anodal side of the cells the protoplasm is coagulated as by the 

 use of cathions in weak solutions ; about the cathode and on the 

 cathodal side of the cells, the protoplasm is liquefied as by the 

 use of anions in weak solutions. Not only are these structural 

 effects the same, but they can be shown to be produced by the 

 same means in each case, /. t\, by electrically charged ions, which 

 are present in very dilute solutions of electrolytes, as we have 

 shown, and which serve to carry the current from pole to pole 

 when it is passed through such weak salt solution as the culture 

 media of paramcecia which were used in the experiment. 



It was formerly supposed that these polar effects were due to 

 the formation of acids on the anodal side of the cell and alkalis 

 on the cathodal side, but we have no satisfactory evidence for 

 such internal polar changes. During the passage of the current, 

 the anions prevail about the cathode, and are constantly diffusing 

 toward the anode. During this passage they are continually im- 

 pinging on the cathodal side of the paramoecia, hence a lique- 

 faction of the protoplasm takes place at these places. Cathions 

 prevail about the anode, and continually impinge on the anodal 

 side of the cells in their diffusion toward the cathode so that 

 coagulation occurs at these points. In either case the structural 

 changes are produced by virtue of the electrical charge which the 

 ions carry, and not by any specific chemical effect of the ions or 

 molecules. We thus see that the chemical and electrical means 

 of modifying the protoplasmic structure are identical. 



It will be remembered that these changes in the structure of 

 the protoplasm produced by solutions of electrolytes or the elec- 

 trical current are the same as those which are brought about in 

 organic colloids by the same means. The alkali-modified colloids 

 in Hardy's experiments were coagulated by cathions in solution 

 or at the anode during the passage of the current. They were 

 liquefied by anions or at the cathodes. It is interesting to note 

 also that in the protozoa a movement of the protoplasmic parti- 

 cles within the cell toward the anode has been observed, which 

 corresponds exactly with the movement in the same direction 

 among the colloidal particles of an alkali-modified colloid. Like 



