156 



PSYCIIOLOOY. 



tlirougli tlie nerve of a frog's gastrocnemius muscle a sue- 

 cession of galvanic shocks : you get a succession of twitches. 

 Increasing the number of shocks does not increase the 

 twitching; on the contrary, it stops it, and we have the 

 muscle in the apparently stationary state of contraction 

 called tetanus. This last fact is the true analogue of what 

 must happen between the nerve-cell and the sensory fibre. 

 It is certain that cells are more inert than fibres, and that 

 rapid vibrations in the latter can only arouse relatively 

 simple processes or states in the former. The higher 

 cells may have even a slower rate of explosion than the 

 lower, and so the twenty thousand supposed blows of the 

 outer air may be 'integrated' in the cortex into a very 

 small number of cell-discharges in a second. This other 

 diagram will serve to contrast this supposition with 

 Spencer's. In Fig. 26 all 'integration' occurs below the 

 threshold of consciousness. The frequency of cell-events 

 becomes more and more reduced as we approach the cells 

 to which feeling is most directly attached, until at last we 

 come to a condition of things symbolized by the larger 

 ellipse, which may be taken to stand for some rather 

 massive and slow process of tension and discharge in the 

 cortical centres, to which, as a whole, the feeling of musical 

 tone symbolized by the line at the top of the diagram 

 simply ami totally corresponds. It is as if a long file 



of men were to start one after 



the other to reach a distant point. 

 The road at first is good and 

 they keep their original distance 

 apart. Presently it is intersected 

 by bogs each worse than the last, 

 so that the front men get so re- 

 tarded that the hinder ones catch 

 up with them before the journej- 

 is done, and all arrive together 

 at the goal.* 



One second of time. 



Fig. 26. 



*The compounding of colors ma}^ be dealt with in an identical way. 

 Helmholtz has shown that if green light and red light fall simultaneously 

 on the retina, we see the color yellow. The mind-stuff theory would in- 

 terpret this as a case where the feeling green and the feeling red 'com- 



