THE PSYCHIC DEVELOPMENT OF YOUNG 
ANIMALS AND ITS PHYSICAL (SO- 
MATIC) CORRELATION, WITH SPECIAL 
REFERENCE TO THE BRAIN. 
IT seemed to me important that psychic and somatic 
development should be traced contemporaneously, so 
closely are they related, and in the preceding papers 
an attempt was made to realise, to some extent, this 
ideal, but as my researches on the brain were not 
completed till after the publication of these investiga- 
tions, I thought it better not to attempt to utilise them 
at the time. The investigation bearing on the functional 
development of the cerebral cortex, with special regard 
to the motor centres, extends to all the groups of 
animals falling under my studies in psychic develop- 
ment, and is presented in the present volume of the 
Transactions, so that it is now possible to deal with the 
most important part of the somatic correlation, viz. 
with the brain. Naturally, I shall draw chiefly from 
the latter paper, and from those on psychic development 
for the facts, etc., on which reliance will be placed in 
attempting further progress, in regard to a more com- 
plete correlation of the somatic with the psychic. 
No attempt will be made in this paper to discuss 
somatic correlation in general, as that subject has been 
treated in the previous papers. 
It would be quite correct to speak of the relations as 
anatomical and physiological correlation, but as move- 
ments are so bound up with the psychic developments of 
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