that by the division of the medulla there has been separated from the
general tissues of the body a repressive force--a something which
normally controls their chemical activity and the production in them of
animal heat.

The existence of nerves whose function is to repress action is no new
discovery in physiology. Readers of _Lippincott's Magazine_ may remember
my description of the pneumogastrics or brake-nerves of the heart, whose
duty it is to control the action of that viscus. Nerves which repress or
inhibit action are spoken of in modern physiology as inhibitory. The
experiments which have been adduced prove that there are nerves whose
function it is to control the general vital chemical actions, and that
the governing centre of these nerves is situated above the medulla
oblongata. To this centre, whose exact location is unknown, the name of
the _inhibitory heat-centre_ has been given.

The way in which galvanization of a nerve, violent injuries and
excessive pain depress the temperature, independently of any action upon
the circulation, is now evident. An impulse simply passes up the
irritated or wounded nerve, and excites this inhibitory heat-centre to
increased action, and the temperature falls because the chemical
movements of the body are repressed.

The method in which fever is produced also becomes very evident when
once the existence of an inhibitory heat-centre has been established.
Any poison having the power to depress, and finally paralyze, this
centre must, if it find entrance to the blood, produce fever. If the
poison, from its inherent properties, or from its being in very small
quantity, only diminishes the activity of the inhibitory heat-centre,
the controlling influence is not entirely removed from the chemical
movements of the body, and only slight fever results; but if the poison
actually paralyzes the inhibitory nerves, a very great rise of
temperature must rapidly follow the complete removal of the brake-power.

As an illustration we may consider the intense rheumatic fever, or the
so-called "cerebral rheumatism," such as affected the young Irishman
whose case has been narrated in the present article. Without any
apparent reason the poison of rheumatism habitually attacks one joint on
one day, and another joint on another day, and with as little apparent
reason it occasionally falls of a sudden upon the inhibitory
heat-centre, and actually paralyzes it. In a few minutes intense fever
is d