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THE PSYCHIC DEVELOPMENT OF YOUNG ANIMALS 153 
edges. These processes take a few days for completion, 
even after there is an obvious opening between the 
lids; and it is very doubtful if the animal sees at all, 
in the proper sense of the word, until the lids are 
completely separated, if even then; so that the eyes 
being open is in itself no guarantee that the animal 
sees, or, at all events, more than light and shadows. 
The slowness of reflex winking to appear in puppies 
is surprising, the more so as mature dogs wink very 
readily when any object is brought near, or moved 
before the eye. 
Quite otherwise is it with mature birds, and it is 
almost impossible to get the young to wink, even on 
touching the lids in some cases I have found. 
In this, and a former litter of St Bernards, the eyes 
began to open on the 11th day, and in a litter of 
Bedlington terriers on the same day, or perhaps a little 
earlier. One writer states that the eyes of dogs open 
on the 8th day. I have never seen this, and do not 
believe it holds for any pure-bred dogs, at all events. 
But individual differences show to the extent of at 
least twelve hours. 
Hearinc.—It is very easy to be deceived in this, on 
account of motor effects resulting from concussion, or 
from contact of blasts of air with the skin. I think 
however, my experiments will be deemed conclusive, 
and the record of the development of this sense very 
full. 
There comes a time, as I have noted, when the young 
dog is more affected by sounds than an older one, 
owing to the less perfect development of his cerebral 
cortex, which part of the brain is associated with all 
higher psychic manifestations, with voluntary move- 
ments, inhibitions, etc. To this the lack of experience 
is to be added, for till the dog has learned better, noises 
of all kinds are excitements which may have unpleasant 
