298 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



effort disturb each other. On the other hand, if they 

 have not a maximal intensity they can take place simul- 

 taneously. I found tJiat easy tasks or the reproduc- 

 tion of simple matters of memory did not lower the 

 maximum of the pressure. 



4. These experiments recall the disturbances of 

 associative memory which were discussed in the 

 preceding chapter. By causing powerful processes 

 of motor innervation to go on, we interfere with 

 all associations, except those which have occurred 

 very frequently. This was the characteristic of the 

 patients mentioned in the preceding chapter. But at 

 the same time it does not exhaust the case. The 

 processes of innervation in the brain of these patients 

 were possibly mutilated not only in intensity but also 

 in other dimensions or directions. 



Perhaps the cases of the inhibition of reflexes also 

 belong in this same category of phenomena. We 

 have mentioned that a dog with severed spinal cord 

 shows pendulum-movements of the hind-legs when 

 they are allowed to hang down. But if we press the 

 skin of the tail gently the pendulum-movements of 

 the legs at once cease (Goltz). Some authors seem 

 to be under the impression that a shock-effect must 

 consist in the exhaustion of the parts under the in- 

 fluence of the shock. This is not necessarily true. 

 The shock-effect may be due to a phenomenon of 

 interference or to a comparatively slight physical 

 change which results in a mutilation of the processes 

 of innervation. 



