68 THE PRINCIPLE OF THE DIliECT Ciiap. III. 



trembled to such a degree from delight, that he could 

 not for some time reload his gun; and I have heard 

 of an exactly similar case with an Australian savage, 

 to whom a gun had been lent. Fine music, from the 

 vague emotions thus excited, causes a shiver to run 

 down the backs of some persons. There seems to be 

 very little in common in the above several physical 

 causes and emotions to account for trembling; and Sir 

 J. Paget, to whom I am indebted for several of the 

 above statements, informs me that the subject is a very 

 obscure one. As trembling is sometimes caused by 

 rage, long before exhaustion can have set in, and as it 

 sometimes accompanies great joy, it would appear that 

 any strong excitement of the nervous system interrupts 

 the steady flow of nerve-force to the muscles. 2 



The manner in which the secretions of the alimentary 

 canal and of certain glands — as the liver, kidneys, or 

 mammae — are affected by strong emotions, is another 

 excellent instance of the direct action of the sensorium 

 on these organs, independently of the will or of any 

 serviceable associated habit. There is the greatest dif- 

 ference in different persons in the parts which are thus 

 affected, and in the degree of their affection. 



The heart, which goes on uninterruptedly beating 

 night and day in so wonderful a manner, is extremely 

 sensitive to external stimulants. The great physiologist, 

 Claude Bernard, 3 has shown how the least excitement 

 of a sensitive nerve reacts on the heart; even when a 

 nerve is touched so slightly that no pain can possibly 



2 Miiller remarks (' Elements of Physiology,' Eng\ 

 translat. vol. ii. p. 934) that when the feelings are very 

 intense, " all the spinal nerves become affected to the ex- 

 tent of imperfect paralysis, or the excitement of trem- 

 bling- of the whole body." 



3 ' Lecons sur les Prop, des Tissus Vivants,' 1866, pp. 

 457-466. ^ 



