THE PSYCHIC DEVELOPMENT OF YOUNG ANIMALS 167 



physical. It is not. easy to make perfectly evident in a 

 diary the extent to which individuality is shown, but 

 even in the blind period it exists, and to a close 

 observer, familiar with dogs, and the particular breed 

 being studied, it shows itself in a variety of ways, often 

 it may be difficult to describe in words. Sometimes, 

 when but a few weeks old, a puppy foreshadows his 

 future in an unmistakable way. 



PERIODS OF DEVELOPMENT. A study of the diary 

 will show that the two great periods are : that before 

 the eyes are open, and that succeeding this one. The 

 time between the opening of the eyes, and the establish- 

 ment of real vision and hearing, constitutes a transition 

 or intermediate period. 



Development is very slow in the first period, and 

 existence almost a vegetative one, yet not wholly so, for 

 by the skin, the muscular sense, to some extent, by taste 

 and smell, by visceral sensations, etc., the animal's 

 nervous centres are being modified. 



The intermediate period is marked by a considerable 

 advance, though slow, as compared with the progress 

 made within the next few days. 



The period between about the 17th and the 45th day 

 is that of greatest importance in the life of the dog. 



After that there is constant improvement, from ex- 

 perience, up to the 60th day, and this is well marked 

 more so than at any later time, but it is not of equal 

 importance with that preceding. 



These periods glide into one another, and many others 

 might be interpolated, but I desire to avoid artificiality, 

 which is sure to result from the attempt at numerous 

 divisions of any kind. 



There is not the sharp line of difference between the 

 dog and other animals, before the eyes are opened and 

 afterwards, which some writers would have us believe, 

 though between the animal, when it can neither see nor 



