The examination of all the tissues and organs of these animals
showed changes in three organs only, and with few exceptions in all
three of these organs--the brain, the adrenals, and the liver.
The extent of these changes is well shown by the photomicrographs
which illustrate the paper on "The Kinetic System" which is included
in this volume. This paper describes many experiments which show
that the brain, the adrenal, and the liver play together constantly
and that no one of these organs--as far at least as is indicated
by the histologic studies--can act without the co-operation
of the other two.

Another striking fact which has been experimentally established
is that the deterioration of these three organs caused by emotion,
by exertion, and by other causes is largely counteracted,
if not exclusively, during sleep. If animals exhausted by the continued
application of a stimulus are allowed complete rest for a certain
number of hours, _*without sleep_, the characteristic histologic
appearance of exhaustion in the brain, adrenals, and liver is not
altered notably, whereas in animals allowed to sleep for the same
number of hours the histologic changes in these organs are lessened--
in some cases obliterated even.

This significant phenomenon and its relation will be dealt with in
a later monograph.

Many of the arguments and illustrations by which the primary
premises were established are repeated--a few in all--many in
more than one of these addresses. It will be observed, however,
that the APPLICATION of these premises varies, and that their
SIGNIFICANCE broadens progressively.