Accumulators of Specific Nervous Energy 293 



another and of decomposing again, and in dynamic 

 equilibrium among themselves. (It may be remarked 

 here that the expression "dynamic equilibrium" of a cir- 

 culatory system is always to be understood in the sense 

 of inalterability for the time in the conditions of move- 

 ment at each point of the system. Thus, for example, 

 the system of distribution of the drinking water of a city, 

 which is fed^from a given constant number of reservoirs, 

 whose head of water is maintained always at the same 

 height, and in which a given constant number of water 

 taps are always open, will settle in a short time into a 

 dynamic equilibrium in our sense, and continue in it so 

 long as the accession of a new reservoir, for example, or 

 the opening of other water taps does not cause the transi- 

 tion to a new dynamic equilibrium.) 



As soon as the discharge of this nervous accumulator 

 occurs, which can produce thus only a single definite 

 specificity of current, and which can discharge itself upon 

 only a single fixed point, it will necessarily effect a single 

 very definite change in the dynamic equilibrium of this 

 given circulatory system. And in the cases in which this 

 change of the dynamic equilibrium requires the doing of 

 a certain amount of work, this required expenditure of 

 work or energy will be very definite for each discharge, 

 and can be provided only by the accumulator itself. Con- 

 sequently, in order that the discharge may take place, this 

 quantity will have to be less than, or at most equal to, 

 that which the accumulator can actually furnish. 



But the quantity of work which each accumulator is 

 capable of furnishing will necessarily be proportional to 

 the mass of the substance which constitutes it. And 

 since, as we saw, the resistance R which each accumulator 

 with its current of definite specificity is able to surmount, 



