Chap. I. SERVICEABLE ASSOCIATED HABITS. 37 



and blowing the nose are completely under our com- 

 mand. 



When we are conscious of the presence of an irritating 

 particle in our nostrils or windpipe — that is, when the 

 same sensory nerve-cells are excited, as in the case of 

 sneezing and coughing — we can voluntarily expel the 

 particle by forcibly driving air through these passages; 

 but we cannot do this with nearly the same force, 

 rapidity, and precision, as by a reflex action. In this 

 latter case the sensory nerve-cells apparently excite 

 the motor nerve-cells without any waste of power by 

 first communicating with the cerebral hemispheres — the 

 seat of our consciousness and volition. In all cases 

 there seems to exist a profound antagonism between the 

 same movements, as directed by the will and by a reflex 

 stimulant, in the force with which they are performed 

 and in the facility with which they are excited. As 

 Claude Bernard asserts, " L'influence du cerveau tend 

 done a entraver les mouvements reflexes, a limiter leur 

 force et leur etendue." 11 



The conscious wish to perform a reflex action some- 

 times stops or interrupts its performance, though the 

 proper sensory nerves may be stimulated. For in- 

 stance, many years ago I laid a small wager with a dozen 

 young men that they would not sneeze if they took 

 snuff, although they all declared that they invariably 

 did so; accordingly they all took a pinch, but from 

 wishing much to succeed, not one sneezed, though their 

 eyes watered, and all, without exception, had to pay 

 me the wager. Sir H. Holland remarks 12 that atten- 

 tion paid to the act of swallowing interferes with the 

 proper movements; from which it probably follows, 



11 See the very interesting* discussion on the whole sub- 

 ject bv Claude Bernard, ' Tissus Yivants.' 1866, p. 353-356. 



12 'Chapters on Mental Physiology,' 1858, p. 85. 



