398 PSYCHOLOGY. 



2. This leads us to the laio of transitoriness, which is 

 this : 31any instincts ripen at a certain age and then fade away. 

 A consequence of this law is that if, during the time of 

 such an instinct's vivacity, objects adequate to arouse it are 

 met with, a habit of acting on them is formed, which re- 

 mains when the original instinct has passed away ; but that 

 if no such objects are met with, then no habit will be 

 formed; 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 feed- 

 ing and ' self-preservation ' may hardly be transient at all, 

 and 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 ob- 

 vious 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 be- 

 ing 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 per- 

 sisted in doing, though beaten back with a small branch dozens of 

 times, and, indeed, cruelly maltreated. 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- 



