INTERFERENCE OF EXCITATIONS 



225 



is stimulated with weak shocks, one can obtain an increase of the 

 tetanus of short duration followed by inhibition. Here, as the 

 result of interference, we have an instance of inhibition with pri- 

 mary tetanus. (Figure 58.) When the tenth root is stimulated 



B 

 Fig. 58. 



with very weak shocks, inhibition of the tetanus produced simul- 

 taneously from the ninth root occurs without primary summation. 

 (Figure 59.) The fact that two series of stimuli, both of which 

 produce dissimilative excitation, bring about an inhibition by 

 their combined action, is sufficient to show the untenability of 

 the Gaskell-Hering hypothesis, that inhibitory processes result 

 from assimilatory excitation. It would be impossible to under- 

 stand how two dissimilatory exciting stimuli, by their simulta- 

 neous action, could bring about assimilatory excitation. When 



