584 



Surface Tension as a Factor Controlling Cell Metabolism. 



By W. Cramer. 



(Communicated by Sir Edward Schafer, F.E.S. Received March 17, 1915.) 



Although it is known that many chemical processes taking place within the 

 cell are due to the actions of ferments, and although we can in many cases 

 separate these ferments from living protoplasm and study their action in 

 vitro, there still remain considerable discrepancies between the processes as we 

 see them occur in vivo and as we study them in vitro. One of the most 

 characteristic features of the processes taking place within the living cell 

 is what, for want of a better term, may be called their " adaptability," that 

 is the delicate sensitiveness with which they respond to very slight changes 

 in the surrounding medium by being retarded, accelerated, or reversed. It 

 is known, of course, that the action of ferments is influenced by changes in 

 temperature or in the alkalinity or acidity of the surrounding medium. But 

 in the case of the living cell these factors remain practically constant, so that 

 their influence can be excluded. We know, too, that many reactions brought 

 about by the action of ferments are reversible, and that the direction in which 

 the ferments act depends upon the concentration of the various substances 

 entering into the reaction. But here again these differences are of an order 

 of magnitude far greater than the variations which exist in the living 

 organism. It is noteworthy, too, that the equilibrium of a reaction brought 

 about by a ferment separated from living protoplasm lies almost always near 

 the point of complete hydrolysis, and contrasts in that respect markedly with 

 the behaviour of the same ferment when its reaction is studied in the living 

 cell, where the reverse process may be found to occur or where very minute 

 changes in the surrounding medium are sufficient to transfer the point of 

 equilibrium from hydrolysis to synthesis. 



If we take the liver cell as an example we find that the living cell can, 

 with equal readiness, transform glycogen into glucose and glucose into 

 glycogen. If the liver is removed from the body a marked glycogenolysis 

 occurs, so that a marked amount of sugar is formed, while the power to 

 synthesise glycogen appears to be almost completely inhibited. In other 

 words, the equilibrium point lies now near the point of complete hydrolysis. 

 The same takes place if an extract of the liver is allowed to act on glycogen 

 or on glucose in the concentrations found in the blood. It is known that the 

 formation of glycogen in vivo occurs when the percentage of blood-sugar is 



