Instinct. 883 



their frequent violation begins that subversion of them called searing 

 the conscience, which ends by the substitution for them of entirely new 

 habits of thought. 



Although every instinct is or has been reasonable, there are many 

 thut never were consciously reasoned out. They are results of the auto- 

 matic reactions of the lower centers, the basal ganglia, cerebellum, me- 

 dulla, &c. It is to this class that most of our earliest instincts belong, 

 and they constitute the principal part of the instincts of the inverte- 

 brates. The}' include all those muscular combinations that are neces- 

 sary to us in our common activities of walking, handling, seeing, eating, 

 &c. , and to other animals in swimming, climbing, leaping, flying, &c. 

 They in general have to be learned, although some are nearly perfect in 

 a very few lessons. 



The mental instincts of animals are largely acquired like those of 

 man. The young of mammals and birds are taught by their elders in 

 many accomplishments and movements in hunting, &c. 



Instincts are not only built up by habitual stimulation, but when the 

 stimulation becomes changed, the instinct is liable to be undone. In- 

 stincts which r-re too firmly grounded to yield to such changed stimuli, 

 become impediments and hindrances. Geology shows the extinction of 

 vast numbers of species brought about by conditions changed too sud- 

 denly to allow the modifications of the instincts to suit. On the other 

 hand, it shows innumerable instances in which the geological changes 

 were slow enough to allow the modifications of animal instinct to keep 

 up. When instinctive habits are of little importance, either as aids or 

 hindrances, they may survive a long time after they have become use- 

 less. This is illustrated by the persistence of wild habits in animals 

 after their domestication ; such as the hiding of their nests by fowls, 

 the hiding of her new born calf by the cow, the turning around of the 

 dog before tying down to sleep. &c. Dogs will turn around thus a num- 

 ber of times and* scratch the surface, no matter if it be a carpet or a 

 pavement, as if they were tramping down the grass and scooping out a 

 hollow in the ground, in the manner of their wild ancestors. A semi- 

 idiotic dog, probably a reversion toward an ancient type, was observed 

 to turn around on a carpet thirteen times before lying down. Jackals, 

 fennecs, and other allied animals in the zoological gardens, turn around 

 in their straw, and make their beds as they would do in prairie grass, or 

 leaves in the woods. 



It is well known that cats bur}' their excrements of both kinds. A 

 kitten was seen scraping ashes over a spoonful of pure water spilt on the 

 hearth. Dogs, wolves, and jackals have not this habit at present, but 

 there is reason to believe their remote ancestors had, for they all make 

 a pretense of covering their excrement by scratching with all four feet 

 as if to heap up u mound of earth ; and they do this on a pavement. 



