270 ANIMAL INTELLIGENCE 
introduction of new voluntary movements, involving 
more and more complex co-ordinations, and from the 
psychic aspect the manifest possession of the power to 
use the machinery of the nervous system and muscles 
in a way that implies the existence of a growing in- 
telligence and will, and the careful observation of a 
litter of puppies, as shown in my paper on the dog, 
will impress both the physiologist and the psycho- 
logist with the rapidly-increasing complexity of the 
life of a young dog, a complexity in which reflex 
and voluntary movements, instincts, intelligence, 
emotions, and will blend in varying, but ever 
augmenting, degrees of intricacy, with all of which 
the rapidly-developing cortex is correlated, and, as 
I have endeavoured to show in earlier papers, there 
is a large amount of somatic correlation over and 
above that of the brain, which is constant as to 
period of development, but with variations for in- 
dividuals and breeds. 
The rapidity of psychic development of a terrier, as 
compared with a St Bernard, is very striking, even 
within the first six weeks of life, but persists to 
maturity; and this, I have found, is correlated with a 
decidedly slower functional development of the cerebral 
cortex in the St Bernard. The difference in the motor 
co-ordinations in the latter and the terrier is so striking 
within the first six or eight weeks of life as to be 
ludicrous. 
Il.—TwHE Cat, THe DoG AND THE CAT COMPARED. 
NEARLY all that has been said of the reflexes of the 
dog applies, of course, to the cat. There are, however, 
as would be expected, some that are peculiar to the cat 
