I am much indebted for advice and suggestion to a number
of my colleagues in the University of Chicago, especially to
Professor H. H. Donaldson, Professor A. W. Moore, and Dr.
J. B Watson. My wife has given me great assistance in
the preparation of my manuscript.

For the use of a number of illustrations acknowledgments
are due to the following authors and publishers: William
James; D. Appleton & Co., publishers of Barker's "The
Nervous System"; W. B. Saunders & Co., publishers of "The
American Text-Book of Physiology"; Walter Scott, Ltd.,
publishers of Donaldson's "Growth, of the Brain"; John
Murray, publisher of McKendrick and Snodgrass' "Physi-
ology of the Sense Organs"; and G. P. Putnam's Sons, pub-
lishers of Loeb's Physiology of the Brain.

J. R. A.

UNIVERSITY OF CHICAGO,
November, 1904.

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