ii] HABITS OF CONVOLUTA 43 



sponse : it has become non-phototropic. On the other 

 hand, in the gloom of an ill-lit cellar, in which the 

 light-intensity approximates to that of its habitat 

 among the masses of brown sea-weed, C. paradoxa 

 becomes somewhat -f- phototropic (Fig. 9, b). 



It is urged not infrequently that reflexes are the 

 nervous units, unalterable in form, of which behaviour 

 and higher phases of nervous activity are composed. 

 The briefest study of the lower animals demonstrates 

 that, though reflexes may be regarded as units by 

 the physiological summation of which behaviour 

 and habit are composed, they may not be regarded 

 as unalterable and inevitable. No more than con- 

 scious acts are reflexes the masters of the organism 

 which exhibits them. They are but servants, and 

 tropistic reflexes serve the master-organism, to 

 draw it this way or that according as it is well 

 that, this or that route be taken. Under un- 

 changing conditions, both with respect to environ- 

 ment and with respect to the state of the organism, 

 the reflex is inevitable. But under such conditions 

 a conscious act is likewise inevitable. Since un- 

 changing internal and external conditions are all 

 but unknown in nature, there will always be scope 

 for modification in the reflex as in the conscious act. 

 If the physiologist is called in to act as umpire in 

 the dialectical game between the advocates of free- 

 will and determinism, he pronounces the game a 



