imelight, and
therefore the best teacher and indicator of the exact definition and
limitations of the normal.

Addison, speaking before the South London Medical Society in 1849,
declared that in all of three afflicted individuals there was found a
diseased condition of the suprarenal capsules, and that in spite of
the consciousness "of the bias and prejudice inseparable from the hope
or vanity of an original discovery ... he could not help entertaining
a very strong impression that these hitherto mysterious organs--the
suprarenal capsules--may be either directly or indirectly concerned
in sanguification (the making of the blood): and that a diseased
condition of them, functional or structural, may interfere with the
proper elaboration of the body generally, or of the red particles more
especially...." A modern, acquainted with after developments, would
say that Addison was very hot upon the trail indeed. But withal,
though he must have been well aware of John Hunter's advice to Jenner
on vaccination, "Don't think, make some observations," his training in
the indirect reasoning and deductions of the clinician prevented him
from going right on to a direct experimental test of his theories.

This Brown-Sequard proceeded to do. Removing the adrenal glands in
several species of animals, he found, meant a terrible weakness in
twenty-four to forty-eight hours, and death shortly after. If only one
were removed, there was no change apparent in the normal animal, but
death occurred rapidly upon removal of the other, even after a long
interval. Furthermore, transfusion of blood from a normal into
one deprived of its suprarenals prevented death for a long time,
indicating that the suprarenals normally secreted something into the
blood necessary to life.

The years 1855-1856 beheld two other important glands of internal
secretion, the thyroid, the gland in the neck astride the windpipe,
and the thymus, in the chest above the heart, make their debut.

The thymus was introduced by the great classic monograph of Friedleben
on the "Physiology of the Thymus," in which he mentioned the usual
forgotten pioneers: Felix Plater, a Swiss physician, who in 1614 had
found an enlarged thymus in an infant dying suddenly, and Restelli,
an Italian, who interested himself in the effects of removal of the
thymus more than ten years before. Friedleben believed that in the
young without a thymus, there occurred a softening of the bones, and
general