~)'l Till; \KKVorS SYSTKM AM) ITS COXSKKN \ I l<>\ 



preliminary classification, may be called adjusters. An- 

 other diagram (Fiji;. 0) may be introduced i<. -how the 

 relation of the adjusters to the reflex act. 



There is an evident economy in this arrangement. It 

 brings large clusters of efferent neurons under the control 

 of single afferent units. Moreover, there is no doubt 

 that adjust ors such as \ve have pictured are often domi- 

 nated by others of a still higher order. Thus we see in the 

 nervous system an organization like that of an army, in 

 which generals are placed over colonels, colonels over 

 captains, etc. In the army the number of officers holding 

 a given rank is greater than the number of their superiors, 

 but less than the number of their subordinates. In the 

 nervous system this is probably true of the units in many 

 of the particular mechanisms, but it may not hold in- 

 variably, since, quite unlike the military condition, a 

 neuron may be under the sway of a number of others of 

 the next grade above. This statement introduces tin- 

 idea that now one and now another element may be 

 responsible for the activity of the same inferior group. 

 It also suggests that there may, in some sense, be a strife 

 among the interlocking neurons. We shall have future 

 occasion to dwell upon the conception that inhibitory as 

 well as excitatory influences may be exerted by certain 

 neurons upon others. 



The following illustration is instructive: A man had 

 climbed out of a sixth story window which he wa- to clean. 

 He stood with his toes upon a narrow ledge, holding 

 meanwhile to the upper sash. A gust of wind took off his 

 hat and both his hands went instantly to his head. At 

 once hi- body began tilling out into space. His hands 

 fell with great speed and force upon the sash, which, 

 fortunately, had not passed out of reach. Here a simple 

 reflex, normal under most circumstances, would have 

 proved di-a-irou-. and was overruled by another making 

 for self-preservation. In all probability no reasoning 

 prore preceded the -ecoiid adjustment. But the train 

 of reflections that followed was siifficientlv vivid, and the 



