PRODUCED BY MENTAL CAUSES. 265 



other much dreaded enemy ; sometimes even in presence of 

 objects really harmless and inanimate, but which a morbid 

 imagination leads it to regard as dangerous and living, as 

 has been shown in the chapter on ' Delusions.' Instances of 

 emotional tremor in the camel, dog, kid and other animals 

 have been given in the c Percy Anecdotes ' by Gall, Bonar, 

 and other writers. In the race-horse tremor is the result 

 of the excitement of emulation ; in the mule and ass it is the 

 fruit frequently of a sense of imminent and serious danger 

 (' Percy Anecdotes ') . In the high-bred horse, too, there is 

 the mere quiver of the mobile lips or nostrils in impatience, or 

 under other forms of emotion, and that of the lower jaw, 

 from the excitement of sport, in the pointer (Baker) . These 

 apparently insignificant lip, jaw, or nostril movements are 

 frequently a very delicate sign of mental agitation or emo- 

 tion in the horse ; and to a less extent in the dog, simply 

 perhaps because in it the nostril and lip are much smaller 

 and less mobile. In the lamb there is the general thrill of 

 happiness, and in the cat, of content or satisfaction. 



There may, however, be a coincidence of mental and motor 

 phenomena, arising from a common cause ; they may not 

 stand to each other in the relation of cause and effect. Thus 

 Pierquin notices the concomitance of sudden terror and 

 tremor in an ape affected with the insanity of sunstroke. 



There are certain other kinds of violent or disordered 

 movement that result from emotional causes, and that are 

 not included in the categories of epileptic or other convul- 

 sions, or of the various forms of tremor. They include 

 various eccentricities of motion, such as gyration, staggering, 

 and rocking movements of body or head. 



Much better marked, however, and more common, is im- 

 mobility motionlessness, incapacity, or inability to move 

 paralysis of motile power or of action a familiar result of 

 fear in the horse and other animals. It occurs, for in- 

 stance, in darkness in the horse (Pierquin) ; in which case 

 a morbid or vivid fancy has doubtless much to do with the 

 generation of fear. This common effect of terror of all kinds 

 frequently leads to non-resistance to an enemy, to easy cap- 

 ture by man. Thus a dog was so terrified on shipboard 



