and, later on in life, when the animal meets the objects, he will altogether fail to react, as at the earlier epoch he would instinctively have done.
No doubt such a law is restricted.Some instincts are far less transient than others -- those connected with feeding and 'self-preservation' may hardly be transient at all, end some, after fading out for a time, recur as strong as ever, e.g., the instincts of pairing and rearing young.The law, however, though not absolute, is certainly very wide-spread, and a few examples will illustrate just what it means.
In the chickens and calves above mentioned, it is obvious that the instinct to follow and become attached fades out after a few days, and that the instinct of flight then takes its place, the conduct of the creature toward man being decided by the formation or non-formation of a certain habit during those days.The transiency of the chicken's instinct to follow is also proved by its conduct toward the hen.Mr.Spalding kept some chickens shut up till they were comparatively old, and, speaking of these, he says:
"A chicken that has not heard the call of the mother till until eight or ten days old then hears it as if it heard it not.I regret to find that on this point my notes are not so full as I could wish, or as they might have been.There is, however, an account of one chicken that could not be returned to the mother when ten days old.The hen followed it, and tried to entice it in every way; still, it continually left her and ran to the house or to any person of whom it caught sight.This it persisted in doing, though beaten back with a small branch dozens of times, and, indeed, cruelly mistreated.It was also placed under the mother at night, but it again left her in the morning."
The instinct of sucking is ripe in all mammals at birth, and leads to that habit of taking the breast which, in the human infant, may be prolonged by daily exercise long be- yond its usual term of a year or a year and a half.But the instinct itself is transient, in the sense that if, for any reason, the child be fed by spoon during the first few days of its life and not put to the breast, it may be no easy matter after that to make it suck at all.So of calves.If their mother die, or be dry, or refuse to let them suck for a day or two, so that they are fed by hand, it becomes hard to get them to suck at all when a new nurse is provided.
The ease with which sucking creatures are weaned, by simply breaking the habit and giving them food in a new way, shows that the instinct, purely as such, must be entirely extinct.
Assuredly the simple fact that instincts are transient, and that the effect of later ones may be altered by the habits which earlier ones have left behind, is a far more philosophical explanation than the notion of an instinctive constitution vaguely 'deranged' or 'thrown out of gear.'
I have observed a Scotch terrier, born on the floor of a stable in December, and transferred six weeks later to a, carpeted house, make, when he was less than four months old, a very elaborate pretense of burying things, such as gloves, etc., with which he had played till he was tired.He scratched the carpet with his forefeet, dropped the object from his mouth upon the spot, and then scratched all about it (with both fore- and hind-feet, if I remember rightly, and finally went away and let it lie.Of course, the act was entirely useless.I saw him perform it at that age, some four or five times, and never again in his life.The conditions were not present to fix a habit which should last when the prompting instinct died away.
But suppose meat instead of a, glove, earth instead of a carpet, hunger-pangs instead of a fresh supper a few hours later, and it is easy to see how this dog might have got into a habit of burying superfluous food, which might have lasted all his life.Who can swear that the strictly instructive part of the food-burying propensity in the wild Canidæ may not be as short-lived as it was in this terrier?
A similar instance is given by Dr.H.D.Schmidt of New Orleans:
"I may cite the example of a young squirrel which I had tamed, a number of years ago, when serving in the army, and when I had sufficient leisure;
and opportunity to study the habits of animals.In the autumn, before the winter sets in, adult squirrels bury as many nuts as they can collect, separately, in the ground.Holding the nut firmly between their teeth, they first scratch a hole in the ground, and, after pointing their ears in all directions to convince themselves that no enemy is near, they ram -- the head, with the nut still between the front teeth, serving as a sledge-hammer -- the nut into the ground, and then fill up the hole by means of their paws.The whole process is executed with great rapidity, and, as it appeared to me, always with exactly the same movements; in fact, it is done so well that I could never discover the traces of the burial-ground.Now, as regards the young squirrel, which, of course, never had been present at the burial of a nut, I observed that, after having eaten a number of hickory-nuts to appease its appetite, it would take one between its teeth, then sit upright and listen in all directions.Finding all right, it would scratch upon the smooth blanket on which I was playing with it as if to make a hole, then hammer with the nut between its teeth upon the blanket, and finally perform all the motions required to fill up a hole -- in the air ; after which it would jump away, leaving the nut, of course, uncovered."
The anecdote, of course, illustrates beautifully the close relation of instinct to reflex action -- a particular perception calls forth particular movements, and that is all.Dr.Schmidt writes me that the squirrel in question soon passed away from his observation.It may fairly be presumed that, if he had been long retained prisoner in a cage, he would soon have forgotten his gesticulations over the hickory-nuts.
