794 SALT ANTAGONISM IN STARFISH EGGS 



of the pure NaCl solution on the living egg (agglutination, cytolytic 

 action, membrane formation, prevention of maturation). 



3. The inference is that the essential factor in these and similar 

 antagonistic and protective actions is the formation of solid water- 

 insoluble colloidal salts {e.g., soaps and proteinates) of calcium 

 (or other metal) with the structural colloids of the protoplasm. Ap- 

 parently the presence of a certain proportion of such compounds 

 is necessary to the structural stability of the living protoplasm, 

 and especially to the water-insolubility and semipermeability of its 

 external layer or plasma membrane. When the cell is immersed 

 in the pure NaCl solution, water-soluble Na compounds are subs- 

 tituted for the insoluble Ca compounds which normally provide the 

 necessary insolubility and coherence, and disintegration results. 



