230 WARFARE IN THE HUMAN BODY 



of tone almost sufficient to result in discharge. Tonus 

 being a state of readiness for activity, all nerves stimulated 

 by conduction from the discharging neurons may raise 

 verbal centres to a condition near to a like discharge. In 

 such cases we have verbal thinking, i.e. impulse not dis- 

 charged over motor tracts leading to speech. These 

 relations of raised or lowered tone, of inhibition or ex- 

 citation, are obviously neuronal functions, and all 

 " thought " is the impulse towards discharge in reactions, 

 forced, useful, or pleasant, under definite stimuli exciting 

 complex reflex arcs. 



Such views, it seems, are easily grasped when we deal 

 with the lower animals, but many find it difficult to believe 

 that the poet's " consciousness " when he writes a poem 

 is in fact a reaction to his internal and external environ- 

 ment, and that the poem is truly as much a reaction 

 product as the bark of a dog or the spring of a tiger. 

 There is, however, no real gap discoverable between the 

 reflex responses of an amoeba, whose irritability as proto- 

 plasm is of the same order, though less specialized, as 

 that of a neuron, and all the spinal and cerebral reflexes 

 of a genius. Such reflexes are, however, more and more 

 complex and " conditioned," i.e. dependent on other 

 reflexes and much more easily inhibited. In such a case 

 inhibition probably means no more than a failure of 

 some synapse to act, while excitation which results in 

 such original graphic verbal reactions as a poem is the 

 functioning of new nerve dendrons hitherto not joined 

 up, and fresh combinations of older ones which have 

 functioned before. 



Certainly the case for such conclusions has been of 

 late immeasurably strengthened by Pavlov. This physio- 

 logist was led to make his experiments by finding that 



