32 INSANITY IN THE LOWER ANIMALS. 



sanity in species that stand nearest man in habits or struc- 

 ture, for instance, in the dog. 



In other animals, as in man, insanity may be said to 

 exhibit two stages of development : 



1. The stage of inception or incubation the premonitory 

 period the condition of changed habit and disposition ; and 



2. The more decided state of alienation proper. 



The symptoms of the first stage have already been con- 

 sidered in the present chapter. The symptoms, on the other 

 hand, of insanity proper are detailed in the chapter devoted 

 to the forms of mental defect and derangement. 



But no practical advantage results from such a classi- 

 fication, or separation of stages. The one group of symptoms 

 passes into the other, and they become variously intermixed, 

 so that it is impossible to draw any scientific line of demar- 

 cation. What is of more importance practically is that 



1. As has already been pointed out, insanity in other 

 animals, as in man, is sometimes preceded by S} r mptoms 

 common to, or resembling those of, acute inflammations of 

 the brain and spinal cord, or their membranes, or of other 

 bodily diseases ; while 



2. The incidence of insanity, whether sudden or gradual, 

 both in other animals and in man, is sometimes most puzz- 

 ling and insidious, requiring all the skill and caution of 

 even the experienced physician and veterinarian to dis- 

 tinguish the true character and significance of the symptoms 

 by which it is marked. 



The period and the circumstances of the invasion or com- 

 mencement of insanity are at all times difficult to determine. 

 At first the symptoms are usually not salient, and are ap- 

 preciable, if so at all, only by the expert (Pierquin). This is 

 the case equally in other animals and man. The early 

 indications, the premonitions or forecastings, of coming 

 mental disaster, are apt to be unobserved and overlooked. 

 Both subsequent progress and beginning, moreover, may be 

 as different in different animals, and even in different indi- 

 viduals of the same species, as they are in different men 

 under different circumstances. 



The suddenness of the seizure may therefore be more 



