4i6 THE COLLOIDAL STATE 



In such instances where the general cytoplasm is in the 

 gel state, the plasma membrane is difficult, if not impossible, 

 visually to demonstrate since the two consistencies closely 

 approximate. But structural differences are recognizable by 

 their physiological behaviour. Thus Chambers found that 

 sodium chloride or potassium chloride injected into an amoeba 

 caused quiescence and liquefaction of the internal protoplasm, 

 but the normal state was regained in time. Calcium chloride 

 or magnesium chloride when similarly injected, solidified the 

 internal protoplasm and the region was permanently injured. 

 On the other hand, when the amoeba was immersed in sodium 

 chloride, the plasma membrane was disintegrated ; potassium 

 chloride had a similar effect but to a lesser degree ; like 

 treatment with calcium chloride or magnesium chloride had 

 no influence so long as the plasma membrane was intact. 



Seifriz agrees that the outer layer of the protoplasm has 

 a morphological identity distinct from the internal mass, but 

 he considers that the difference in constitution is one of degree 

 rather than of kind. The characteristic physical properties of 

 protoplasm, capacity for imbibition, rigidity, and especially 

 elasticity, indicate, according to Seifriz, a gel of fibrous 

 structure. 



The interaction between protoplasm as a colloid, and 

 electrolytes dissolved in the cell sap or in the liquid medium 

 in which the protoplasm is suspended, must also be borne in 

 mind. 



Clowes * has propounded a theory of the mechanism of 

 permeability based upon the phase relationships between the 

 particles of the colloidal protoplasm and the continuous 

 medium in which they are suspended. Arguing from the fact 

 that calcium soaps favour the formation of a water in oil 

 emulsion, while sodium soaps favour the oil in water emulsion, 

 he suggests that thepermeabihty of the protoplasmic membrane 

 might be influenced by a predominance of either sodium or 

 calcium ions ; thus the presence of an excess of sodium ions 

 would permit the passage of water-soluble substances between 

 the particles of an oily disperse phase, while, owing to their 

 * Clowes : " J. Physical Chem.," 1916, 20, 407, 



