444 PROTOPLASM 



a physiologically balanced solution, where the proportion of 

 sodium to calcium is 50 : 1 or 2, as it is in blood and sea water. 

 If we accept this hypothesis, the question arises, Just which 

 property of protoplasm is it upon which the two ions have 

 opposite effects? 



The effect of sodium and of calcium on protoplasm is a con- 

 troversial subject, though the consensus of opinion appears to 

 indicate that, in general, sodium disperses and calcium aggre- 

 gates. The work of Osterhout showed that sodium increases 

 and calcium decreases protoplasmic permeability (though 

 Fitting found that potassium, which one would expect to act hke 

 sodium, decreases permeability ; and there were also qualifications 

 in regard to calcium in Osterhout's work). The work of Ruth 

 Addoms indicates that sodium, potassium, calcium, magnesium, 

 zinc, and aluminum salts all coagulate the protoplasm of root 

 hairs. But the experiments of Faure-Fremiet and of Plowe 

 support our original and rather generally accepted contention 

 that protoplasm thickens in the presence of calcium and exhibits 

 extraordinary elastic qualities; while in the presence of sodium 

 it is less thick and poorly elastic. There is the further experi- 

 mental evidence that a torn protoplasmic surface is repaired 

 only in the presence of calcium, owing to the aggregating (gelat- 

 ing) effect of the latter, an effect that sodium lacks. This action 

 is further indicated by the fact that when calcium is injected 

 into a cell, the micropipette may be removed immediately 

 without danger of loss of protoplasm, due to the rapid coagula- 

 tion of the protoplasm by the calcium at the point of injection. 

 With sodium, this is never true, and the pipette cannot be with- 

 drawn immediately or quickly. Freundlich, thinking of the 

 action of salts upon colloidal systems in general, suggests that 

 the colloidal material in protoplasm is precipitated or aggre- 

 gated by the calcium ion and dispersed by the sodium ion. 

 Hober found this to be true in the case of proteins. Gellhorn 

 states that calcium reduces the imbibition qualities of protoplasm 

 and that sodium augments them. 



If the opinion of the majority holds, then it seems probable 

 that the antagonistic action that sodium and calcium exhibit is 

 due to the dispersing (liquefying) effect on protoplasm of the 

 former and the aggregating (coagulating) effect of the latter. 

 The antagonistic action of these two elements as shown by their 



