216 THE PRINCIPLES OF HEREDITY 



which impels to the removal of it ; and always, in a shorter or 

 longer time, the voluntary impulse tends to be overpowered 

 by the involuntary reaction. The duration of the voluntary 

 control over a reflex act is determined by its usefulness. Thus 

 it is short in the case of breathing, coughing, and sneezing 

 for here, as a rule, it is needed only during the act of swallow- 

 ing or other occasions of short duration. It is much longer 

 in the case of the reflexes of the bladder and the lower 

 intestines, which it is often useful to control for a more 

 lengthened period. 



367. An irritant in the larynx, or on the conjunctiva, is 

 painful and the cause of reflex action. But here again the 

 true function of the feeling is to impel to voluntary action. 

 Not only do we wink or cough, but we take additional 

 measures. We rub our eyes or hold our breath, or move 

 away from a dust or smoke-laden atmosphere. Were there 

 no incitement to voluntary action the feeling, in such cases, 

 would be a useless epi-phenomenon. A mere sense-impres- 

 sion or a stimulus devoid of consciousness would serve as 

 well as indeed it does in the case of all those internal 

 reflexes which are not controllable by voluntary effort. 

 Sometimes under abnormal conditions pain does not precede 

 but accompanies the performance of a reflex action. But 

 here again its function is to initiate voluntary action. Thus 

 when we experience angina pectoris, we relieve the labouring 

 heart by keeping still. When we have pain in the intestines 

 we seek to empty them. Indigestion tends to cause us to 

 abstain from food. 



368. Pleasure also is experienced during the actual 

 performance of some reflexes, but, as in the case of pain, its 

 function is then not to bring about directly the reflex act, 

 but, by the promise of it, to initiate definite voluntary 

 actions, which in turn supply the stimulus for the reflex. 

 Thus the pleasure which is experienced during the perform- 

 ance of the sexual act prompts to the voluntary actions which 

 necessarily precede it. Thus, again, the pleasure derived 

 from satisfying hunger prompts to the performance of the 

 often very complex voluntary actions which precede the 

 swallowing of food. 



369. All the actions of living beings are voluntary, reflex, or 

 protoplasmic. Not a muscle contracts, not a gland secretes 

 but the action comes under one or the other category ; and 

 always voluntary actions, unlike reflexes, are directly initiated 

 by desires, wishes, wills, which in turn are awakened by the 

 actual existence of, or the prospect of future pleasures or 



