APPLICATION OF THE FORMULA OF AUTOCATALYSIS 527 



deal with a colloidal fatty acid which is deposited along the path of 

 an impulse and remains to accelerate or, if it is in excess, to retard a 

 subsequent impulse. 



THE APPLICATION OF THE FORMULA OF AUTOCATALYSIS TO 

 CENTRAL NERVOUS PHENOMENA. 



The time-relations of any Voluntary Movement are primarily governed 

 by events which occur in the central nervous system. This may readily 

 be inferred from the fact that it requires, not a single impulse or stim- 

 ulus to produce any coordinated movement, but a stream of impulses 



FIG. 46. Photograph of a drawing-board specially constructed to record the time- 

 relations displayed in the execution of a simple volition (the drawing of a straight 

 line). 



which must be maintained throughout the duration of the act which 

 is performed. A single stimulus, when applied to voluntary or striated 

 muscle, only produces a single rapid twitch; a prolonged tetanic or 

 semitetanic movement such as that involved in the performance of 

 any muscular exertion is only possible to evoke by a rapid succession 

 of stimuli. Moreover the performance of a coordinated muscular act 

 such as that of bending the arm, involves a simultaneous discharge 

 of stimulatory impulses to the flexor, and inhibitory impulses to the 

 opposing extensor muscles of the limb. 



The time-relations of a simple voluntary movement, such as that 

 implied in drawing a straight line with a pencil upon a board, may be 

 accurately investigated by a method which was originally proposed by 



