MENTAL DIFFEEENCE AND DISORDER. 245 



temper and defects of mental character, constitutional ir- 

 ritability, inertia mental and physical, the most serious 

 conjunct mental and bodily diseases such as rabies in 

 menagerie and household pet animals. The unhealthy, 

 unnatural conditions which conspire to the production in 

 them of such results include 



1. Captivity enforced confinement in various forms and 

 degrees. 



2. The repression or non-gratification of the natural 

 instincts. 



3. Defective air-change. 



4. Deficient exercise mental as well as bodily. 



5. Overfeeding with unsuitable food. 



6. Petting or pampering, over-indulgence, the non-cor- 

 rection of bad habits, encouragement of laziness. 



Captivity in zoological gardens, menageries, kennels, 

 aviaries, cages, or aquaria operates deleteriously on the 

 mental character of the animals confined, not merely by the 

 galling sense of the loss of freedom, but in a great variety of 

 other ways, partly physical, partly mental. Artificial or 

 compulsory confinement at once affects an animal's docility : 

 it produces a morbid sensitiveness, both to mental and 

 physical influences ; it gives rise to various degrees of dis- 

 tress of mind, to irritability, irascibility, pugnacity, ferocity, 

 or fury ; it is apt to lead ultimately to nostalgia, melancholia, 

 suicide, and even, in specially active animals, such as the 

 ape, to idiocy, marasmus, and death. Excessive confine- 

 ment in the dog produces fierceness and intractability 

 (Lewes). The Aoudad sheep, which is described as naturally 

 of very uncertain temper, becomes morose and suspicious in 

 confinement. ' Sometimes he seems to be seized with an 

 irresistible desire for assaulting something, 5 according to 

 Wood, who has described other effects of captivity in various 

 animals in his series of papers on the Zoological Gardens of 

 London. 



Captivity aggravates a natural tendency to pugnacity or 

 irascibility in some animals, while it creates these qualities 

 in certain others ; so that a disposition to fight is frequently 

 exhibited on trivial provocation, as in the ruff (Darwin). 



