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ANIMAL INTELLIGENCE. 
his labours — the culmination of his experiment in the 
transformed psychology of the dog. 
In my next work I shall treat of this subject with the 
fulness that it deserves — especially in its relation to the 
origin of instincts and the development of the moral 
sense ; but to enter upon this topic at present would 
demand more space than can be allowed. 
To do full justice to the psychology of the dog a 
separate treatise would be required. Here I can only 
trace a sketch. 
Memory . 
As regards memory, one or two instances will suffice. 
Mr. Darwin writes : 6 1 had a dog who was savage and 
averse to all strangers, and I purposely tried his memory 
after an absence of five years and two days. I went near 
the stable where he lived, and shouted to him in my old 
manner ; he showed no joy, but instantly followed me out 
walking, and obeyed me, as if 1 had parted with him only 
an hour before. 5 1 
It is not only persons or places that dogs remember 
for long periods. I had a setter in the country, which one 
year I took up with me to town for a few months. While 
in town he was never allowed to go out without a collar 
on which was engraved my address. A ring upon this 
collar made a clinking sound, and the setter soon learnt to 
associate the approach of this sound with the prospect of 
a walk. Three years afterwards I again took this setter 
up to town. He remembered every nook and corner of 
my house in town, and also his way about the streets, and 
the first time that I brought his collar, slightly clinking 
as before, he showed by his demonstrations of joy that he 
well remembered the sound with all its old associations, 
although he had not heard this sound for three years. 
Emotions . 
The emotional life of the dog is highly developed — 
more highly, indeed, than that of any other animal. His 
1 Descent of Man, p. 74. 
