antitoxin directly into that, the disease was stopped. Or it might even
be "headed off" by the crude method of cutting directly across the
nerve-trunk at a point above that yet reached by the infection.

The commonest and most fatal of all forms of general diseases of the
nervous system are those which are due to the later extensions of
general infections.

First and foremost stands syphilis, due to the invasion of the blood by
a clearly defined _spirillum_, the _Treponema pallida_ of Schaudinn.
This first attacks the mucous membranes of the throat and mouth, then
the skin, then the great internal organs like the liver and stomach,
then the bones, and, last of all, the nervous system. The length of time
which the poison takes to reach the nervous system is something which at
first sight is almost incredible, viz., from one and a half to fifteen
years. It is true that in rare instances brain symptoms will manifest
themselves within six or eight months; but these are usually due to
pressure by inflammatory growths on the bones of the skull and its
lining membrane (_dura mater_). It is not too much to say that this
disease plays the greatest single role in nervous pathology. Three of
the commonest and most fatal diseases of the spinal cord and brain,
_paresis_ (general paralysis of the insane), _locomotor ataxia_, and
_lateral sclerosis_, are due to it.

Naturally, when a poison has taken a decade or a decade and a half to
penetrate to the nerve-tissues, it does irreparable damage long before
it can be dislodged or neutralized.

A similar aftermath may occur in almost all of the acute infectious
diseases. Every year adds a new one to the list capable of causing
cerebral complications. Tuberculosis, diphtheria, scarlet fever,
typhoid, smallpox, influenza, have now well-recognized cerebral and
nervous complications, some temporary, some permanent. A form of
tuberculosis attacking the coverings (_meninges_) of the brain--hence
known as meningitis--is far the commonest fatal brain-disease of
infancy and childhood.

Perhaps the most striking illustration of just how acute affections
attack the nervous system, is that furnished by diphtheria. A child
develops an attack of this disease, passes the crisis safely, and begins
to recover. A few days later, it is allowed to sit up in bed. Suddenly,
after some slight exertion, or often without any apparent cause, the
face blanches, the eyes stare widely, the child gasps two or th