MECHANISM OP PROCESS OF DEATH 57 



The fact that in all these cases there is a rise in 

 resistance followed by a fall suggests that there are 

 two processes at work, one producing an increase and the 

 other a decrease. In order to picture a mechanism which 

 would account for this the writer has assumed that at 

 the surface of the cell there is a substance, M, forming 

 a continuous layer 29 whose thickness determines the 

 amount of resistance. It is assumed that the thickness 

 of this layer is increased by the breaking down of a 

 substance, A, to form M, according to the monomolecular 

 reaction A > M. At the same time M breaks down to 

 form a substance, B, according to the monomolecular 

 reaction, M >B. The two reactions go on simultan- 

 eously according to the scheme 30 A-r-*-M >B. 



It is obvious that if the rates of the reactions are 

 such that M is formed as rapidly as it is decomposed, it 

 will remain constant in amount; and that an increase in 

 the velocity of the first reaction will cause M to increase, 

 while an increase in the velocity of the second reaction 

 will cause M to decrease. 



The nature of this process is evident from a considera- 

 tion of Fig. 27. If the reservoir A be filled with water 

 while M and B are empty, and if water be allowed to 

 flow from A into M, the amount of water in M (for 

 convenience this amount is called y) will first increase 

 and then decrease. The rate of increase and decrease 

 and the maximum attained will depend on the relation 

 between the two outlets K l and K*. We may suppose 

 that if K! is equal in diameter to K 2 , we get the upper 



v It is recognized that the hypothesis will apply if the layer is not 

 continuous and also if the change in properties of the layer is other than 

 that of thickness. 



30 These reactions are regarded as reversible or practically so. 



