170 MENTAL EVOLUTION IN ANIMALS. 



worthy of remark that, unlooked for, I met with in the 

 course of experiments some very suggestive, but not yet 

 sufficiently observed, phenomena ; which, however, have led 

 me to the opinion that not only do the animals learn, but they 

 can also forget — and very soon — that which they never 

 practised. Further, it would seem that any early interference 

 with the established course of their lives may completely 

 derange their mental constitution, and give rise to an order of 

 manifestations, perhaps totally and unaccountably different 

 from what would have appeared under normal conditions. 

 Hence I am inclined to think that students of animal 

 psychology should endeavour to observe the unfolding of the 

 powers of their subjects in as nearly as possible the ordinary 

 circumstances of their lives. And perhaps it may be because 

 they have not all been sufficiently on their guard in this 

 matter, that some experiments have seemed to tell against the 

 reality of instinct. Without attempting to prove the above 

 propositions, one or two facts may be mentioned. Untaught, 

 the new-born babe can suck — a reflex action ; and Mr. Her- 

 bert Spencer describes all instinct as ' compound reflex 

 action ; ' but it seems to be well known that if spoon-fed, and 

 not put to the breast, it soon loses the power of drawing milk. 

 Similarly, a chicken that has not heard the call of the mother 

 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 (? until) ten clays 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 maltreated. It was 

 also placed under the mother at night, but it again left her in 

 the morning. Something more curious, and of a different 

 kind, came to light in the case of three chickens that I kept 

 hooded until nearly four days old — a longer time than any I 

 have yet spoken of. Each of these on being unhooded 

 evinced the greatest terror of me, dashing off in the opposite 

 direction whenever I sought to approach it. The table on 

 which they were unhooded stood before a window, and each 

 in its turn beat against the glass like a wild bird. One of 

 them darted behind some books, and, squeezing itself into a 



