REFLEX ACTIONS 371 



of favourable variations. Lastly, through the continued action of 

 Natural Selection, sensations took on those peculiar tones which 

 we designate as pleasure and pain. Thereupon desire and will 

 came into being. The animal was now no longer an automaton 

 in the ordinary sense of the word. It felt, and in a real sense 

 desired ; and some of its activities were under the control of its 

 desires, or rather of the will which the desires awakened. The 

 whole process, I suppose, involved a very gradual co-ordinated 

 change in which other cells besides nerve cells participated. 

 There was no mutation, no sudden appearance of nervous tissue 

 or of mind ; for such a sudden development could have been useful 

 only if it had involved simultaneous changes in several classes 

 of cells changes so numerous, complex, and adaptive, that their 

 simultaneous occurrence would have been altogether miraculous. 



613. All the movements of living beings, which result from 

 their vital activities but are not under nervous control, may be 

 termed ' protoplasmic.' The movements of plants and unicellular 

 animals and ciliary movements are examples. Movements made 

 under nervous control are either reflex or voluntary. All move- 

 ments under nervous control, but with which no feeling is 

 associated, are reflex. There are many such in our bodies, for 

 example the normal movements of our heart and intestines. But 

 some movements, which are rightly termed reflex, have a great 

 deal of feeling associated with them. Sneezing and the con- 

 vulsions resulting from tickling are examples. Here, not only does 

 feeling accompany the action, but it initiates it. Neither sneezing 

 nor the convulsions of tickling occur in the absence of feeling ; for 

 example, in people under the influence of chloroform. If I cough 

 because I choose, the action is voluntary ; if I cough because I 

 must because an irritation in the larynx compels me to cough 

 the action is involuntary. But often I can control the reflex, and 

 delay, and in some cases even prevent it. A reflex action, there- 

 fore, is not necessarily one which is not associated with sensation, nor 

 one which is not initiated by sensation, nor one which is not 

 controllable by the will. It is one which is under nervous control 

 but which is not directly INITIATED by the will. This definition 

 is unlike those commonly accepted, but I think it can be justified. 



614. The same action may be voluntary at one time and reflex 

 at another. If the reader will think of all the reflexes he can call 

 to mind, he will find that their distinguishing peculiarity is that 

 they cannot be set agoing by the direct impulse of the will. Thus 

 no matter how strong his willing he cannot really sneeze when he 



