136 RESPONSE IN THE LIVING AND NON-TIVi ee 
record in fig. 85 shows how individually feeble stimuli 
become markedly effective by superposition. 
Superposition of stimuli.—The additive effect of suc- 
ceeding stimuli will be seen from the above. The fusion 
of effect will be incomplete if the frequency of stimula- 
tion be not sufficiently great ; but it will tend to be more 

Fic. 86.—INcoMPLETE AND CoMPLETE Fusion oF Errect 1x TIN 
As the frequency of stimulation is increased the fusion becomes more and more 
complete. Vertical line to the right represents ‘1 volt. 
complete with higher frequency of stimulation (fig. 86). 
We have here a parallel case to the complete and in- 
complete tetanus of muscles, under similar conditions. 
By the addition of these rapidly succeeding stimuh, 
a maximum effect is produced, and further stimulation 
adds nothing to this. The effect is balanced by a force 
