48 FORMS OF MENTAL DEFECT AND DERANGEMENT. 



on the head, apoplexy, and cerebral disturbance of any kind ; 

 while Franconi alludes to it as the result of an acute 

 cerebral affection in the horse. 



Broderip mentions senile dementia as taking the form of 

 a kind of lethargy in the parrot. In that animal in talking 

 animals in general this and other forms of insanity are 

 marked occasionally by incoherence of speech, as well as by 

 that tendency to excessive garrulity or loquacity, to useless 

 and tiresome repetition of words or phrases, the result per- 

 haps partly of loss of memory, that is so characteristic also 

 of senility in man. The mental disorders that occur in 

 middle life in the lower animals, as in man, are characterised 

 generally either by 



1. General excitement, intensity and peculiarity of action. 



2. Depression, with unnatural lack of action. 



3. The development of delusions, especially of fear; or of 



4. Morbid impulses and propensities. 



Of the first group the commonest form is mania, which 

 has long been familiar under the terms madness, frenzy, 

 franticness, fury, ferocity, furiosity, or infuriation. It has 

 hitherto been erroneously assigned, as a mere secondary con- 

 dition, by various veterinary authors, to arachnoiditis, cepha- 

 litis, phrenitis, or other acute inflammations of the brain or 

 its membranes. No doubt it is true that mental excitement 

 of a maniacal character, sometimes or generally, accom- 

 panies these local disorders both in man and other animals. 

 But in other animals, as in man, these cerebral or meningeal 

 inflammations are comparatively rare, while mania in both 

 is comparatively common, and in both, too, it presents the 

 same general characters. 



Mania is commonly known in its suddenly-developed, 

 ephemeral, acute form, for the simple reason that it is never 

 allowed by man to become chronic. The furious, dangerous, 

 maniacal animal and, unfortunately, also the animal which 

 is merely supposed to be so is shot, or otherwise destroyed 

 as summarily as possible. But mania is sometimes seen in 

 a chronic form in wild animals. Thus Baker describes what 

 appears to have been chronic mania in a bull hippopotamus, 

 of which he says: f I never witnessed such determined and 



