instrument.

It seemed to consist of a little cylinder of glass immersed in water
kept at the temperature of the body. Between two minute wire pincers or
serres, in the cylinder, was a very small piece of some tissue. To the
lower serre was attached a thread. The upper one was attached to a sort
of lever ending in a pen that moved over a ruled card.

"Every emotion," remarked Kennedy as he watched the movement of the pen
in fine zigzag lines over the card, "produces its physiological effect.
Fear, rage, pain, hunger are primitive experiences, the most powerful
that determine the actions of man. I suppose you have heard of the
recent studies of Dr. Walter Cannon of Harvard of the group of
remarkable alterations in bodily economy under emotion?"

I nodded and Kennedy resumed. "On the surface one may see the effect of
blood vessels contracting, in pallor; one may see cold sweat, or the
saliva stop when the tongue cleaves to the roof of the mouth, or one may
see the pupils dilate, hairs raise, respiration become quick, or the
beating of the heart, or trembling of the muscles, notably the lips. But
one cannot see such evidences of emotion if he is not present at the
time. How can we reconstruct them?"

He paused a moment, then resumed. "There are organs hidden deep in the
body which do not reveal so easily the emotions. But the effect often
outlasts the actual emotion. There are special methods by which one can
study the feelings. That is what I have been doing here."

"But how can you?" I queried.

"There is what is called the sympathetic nervous system," he explained.
"Above the kidney there are also glands called the suprarenal which
excrete a substance known as adrenin. In extraordinarily small amounts
adrenin affects this sympathetic system. In emotions of various kinds a
reflex action is sent to the suprarenal glands which causes a pouring
into the blood of adrenin.

"On the handkerchief of Gloria Brackett I obtained plenty of
comparatively fresh blood. Here in this machine I have between these two
pincers a minute segment of rabbit intestine."

He withdrew the solution from the cylinder with a pipette, then
introduced some more of the dissolved blood from the handkerchief. The
first effect was a strong contraction of the rabbit intestine, then in a
minute or so the contractions became fairly even with the base line on
the card.

"Such tissue," he remarked, "is noticeably affected by even one part in
over a