iations occurred in all three
components of the apparatus, the viscera, the nerves, and the
endocrines. Now variations in the viscera and the nerves are
essentially grossly physical and quantitative. That is, there may be a
bigger stomach or a smaller stomach, larger nerve fibres or smaller.
And as Life always has worked with a large margin of safety, and
always played for safety first as regards quantity, these variations
have not become of much significance for the history and destiny of
the animal.

But variations among the endocrines made a tremendous difference. To
have very much thyroid and very little pituitary, much adrenal and not
enough parathyroid meant a great deal to the Organism as a whole,
as well as to the vegetative apparatus. For states of tension and
relaxation, activity and inactivity in the nerves and viscera would be
determined by these variations in the ratio between the variants. The
vegetative apparatus in its virginity, say in the new-born infant, may
be said to have its development primarily determined by the reaction
potentials of the endocrine part of it, that is the latent power of
each gland to secrete at a minimum or a maximum, and the balance
between them.

EDUCATION OF THE VEGETATIVE SYSTEM

3. Training or education involves, beside other effects, a training
of the endocrines, and hence of the entire vegetative apparatus, to
respond in a particular way to a particular stimulus. Experience is
like the introduction of new push-buttons, levers, and wheels into the
mechanism. All learning which calls out or arrests the functioning of
an instinct, must, from what we have learned of the chemical dynamics
of instincts as reactions between hormones, nerves and viscera, affect
the vegetative system. When there is a conflict between two or
more instincts, between pressures of energy flowing in different
directions, there may be compromise and normality, or a grinding of
the gears and abnormality.

Where does the brain come in, in all this? As the servant of the
vegetative apparatus. To call it the master tissue is manifestly
absurd, when it can only be the diplomatic constitutional monarch of
the system. It can, in fact, act only as the great central station
for associative memory, as only one of the factors implicated in
education.

The most powerful educative agents of the vegetative apparatus of a
human being are the other humans around him. And they comprise the
most powerful of the e