Observations on Young Mammals. 121 



two several elements in the final product. If we add water 

 to our whisky, there is no longer pure whisky ; the whisky 

 has been more or less modified, but the spirit is still 

 there none the less, and we cannot neglect its presence. 

 So, too, if we add the water of experience to the whisky 

 of instinct, we have a joint product of which so much comes 

 from the bottle and so much comes from the jug. And 

 when Dr. Mills contends that in the kitten "its psychic 

 life is determined by experience," we must take him to 

 mean that the whisky of instinct is, as a matter of fact, 

 always more or less watered down in the course of in- 

 dividual development. 



When animals are brought up by their parents, it is 

 often a matter of diificulty to determine how far any 

 specially characteristic behaviour is due to the influence of 

 the parent, whose behaviour is similar, and how far it 

 is due to instinct. But when the young are separated 

 from their parents at an early age, the instinctive basis is 

 often rendered more clear and obvious. The following 

 observations of Mr. Charles F. Batchelder, which he has 

 kindly given me permission to quote, are of interest 

 in this connection. 



" The nest in which our grey squirrel (Sciurus caro- 

 linensis leucotis, Sapper) rears its young is usually built 

 among the higher branches of some large tree. It is a 

 bulky mass of sticks and leaves, entirely covered above, 

 and entered only by a small passage through the side 

 of the structure. In the middle is a cavity, softly lined, 

 where the young are born, and where they spend their 

 infancy, cut off from sight of the outside world. 



" From such a nest, near the top of a tall white pine 

 (Pinus strobus, Linn.), on May 12, 1877, I obtained two 

 young grey squirrels, out of a litter of four. They were so 

 young and feeble that, as they clung to my rough woollen 



