MENTAL DIFFERENCE AND DISOEDER. 241 



associations, whether with persons, other animals, places, or 

 things, are all not infrequent causes even of suicide on the 

 one hand, and of murder on the other ; while their minor 

 effects are treated of in detail in the chapters on ' Sensitive- 

 ness,' and on the f Bodily Eesults of Mental Causes.' So that 

 what we call ' disappointments in love,' 6 disappointed affec- 

 tions,' ' unrequited love,' ' hope deferred,' and ' blighted 

 hopes,' are quite as frequent causes of mental depression 

 and its sequelae in other animals as in man. 



Suggestion would also appear to be occasionally influential, 

 in conjunction with impulse, in the sudden development of 

 certain forms of insanity for instance, of murderous mania. 

 Among other animals, as in man, it is perhaps scarcely 

 surprising 



How. oft the sight of means to do ill deeds 

 Makes ill deeds done ! 



The sight, usually unexpected, of an enemy -sometimes 

 man himself in a state of helplessness from unconscious- 

 ness, sleep, inebriety, illness, accident, or disease, generates 

 on the moment the ideas of opportunity and revenge ideas 

 that are forthwith acted upon, too probably with fatal effect. 

 Thus in captive feral animals in the lions, tigers, leopards, 

 and rhinoceroses of our menageries the sight of a tyran- 

 nical keeper off his guard, or without his usual weapon, fre- 

 quently suggests the dangerous impulsive spring or charge. 



As has already been explained, mere novelty of sight, 

 sound, or position is frequently sufficient to induce not only 

 surprise or wonder, but alarm, terror, or mental shock, which, 

 if protracted or intense, may lead by paralysis of thought or 

 action to serious accidents to the animals themselves or to 

 man. Thus it is probably the novelty of the position in lost 

 city dogs that leads in them to a sort of mental paralysis, to 

 a degree of bewilderment that renders them eminently ner- 

 vous and suspicious. What is simply unexpected and unusual, 

 what is new or novel, what is seen for the first time, is 

 always apt in certain birds and in many other animals 

 especially those that are young, nervous, or unaccustomed 

 to man to produce a condition which, if there is action, is 

 usually denominated panic, and if inaction, stupidity. Thus 



VOL. II. E 



