THE PSYCHIC DEVELOPMENT OF YOUNG ANIMALS 155 



scarcely to be recognised. The ear, in fact, grows and 

 differentiates after birth in somewhat the same way 

 as the eyelids, but the latter are invariably in advance, 

 so that there are physical reasons for the deafness of 

 puppies. Even after the ear seems to be opened up, 

 the introduction of a fine probe is impossible, as I have 

 shown. 



Psychic manifestations may be looked at from so 

 many different points of view, and the correct inter- 

 pretation is so often doubtful, especially in the lower 

 animals, one's explanations are apt to be so artificial, 

 narrow, or otherwise imperfect, that I shall, under 

 several headings, now refer to the early development 

 of the puppy. 



PLAY. I have endeavoured to follow very closely 

 the development of the play instinct, so important is it 

 as a means of physical and psychic development, as 

 well as an indication and an index of the latter in fact 

 of both. The reader is referred to records of the 13th, 

 15th, 21st, 27th, and 32nd days more especially. I 

 have felt keenly my inability to record all that I have 

 seen in this connection, not to mention the thoughts 

 suggested, which lack of space prevents me making 

 even an attempt to indicate. 



What is play? One observes, first of all, that the 

 puppy uses its mouth generally on a fellow, then, or 

 simultaneously, its paws ; but soon the movements 

 are more complicated, prolonged, and accompanied by 

 various vocal expressions, which are of a significance 

 which varies with the age of the puppy. 



There is not the slightest attempt at play during 

 the period of eye-closure. 



At first, playing seems to arise in part from an 

 excess of motor energy which must be discharged, 

 and as it is in the nature of the dog to use his jaws 

 so much, the play takes the special form of biting ; then 



