CLASS THIRD.
OF NARCOTICO-ACRID POISONS GENERALLY.
The third class of poisons, the narcotico-acrids, includes those which
possess a double action, the one local and irritating like that of the
irritants, the other remote, and consisting of an impression on the
nervous system.
Sometimes they cause narcotism; which is generally of a comatose nature,
often attended with delirium; but in one very singular group there is
neither insensibility nor delirium, but merely violent tetanic spasms.
At other times they excite inflammation where they are applied. This
effect, however, is by no means constant. For Orfila justly observes,
that under the name of narcotico-acrids several poisons are usually
described which seldom excite inflammation. Those which inflame the
tissues where they are applied rarely occasion death in this manner.
Some of them may produce very violent local symptoms; but they generally
prove fatal through their operation on the nervous system.
For the most part, their narcotic and irritant effects appear
incompatible. That is, when they act narcotically, the body is
insensible to the local irritation; and when they irritate, the dose is
not large enough to act narcotically. In large doses, therefore, they
act chiefly as narcotics, in small doses as irritants. Sometimes,
however, the narcotic symptoms are preceded or followed by symptoms of
irritation; and more rarely both exist simultaneously.
Most, if not all, of them, to whatever part of the body they are
applied, act remotely by entering the blood-vessels; but it has not been
settled whether they operate by being carried with the blood to the part
on which they act, or by producing on the inner membrane of the vessels
a peculiar impression, which is conveyed along the nerves. Some of them
produce direct and obvious effects where they are applied. Thus
monkshood induces a peculiar numbness and tingling of the part with
which it is placed in contact. The organs on which they act remotely are
the brain and spine, and sometimes the heart also.
The appearances in the dead body are, for the most part, inconsiderable;
more or less inflammation in the stomach or intestines, and congestion
in the brain; but even these are not constant.
As a distinct class, they differ little from some poisons of the
previous classes. Several of the metallic irritants, and a few vegetable
acrids are, properly speaking, narcotico-acrids: they excite either
narcotism or irritation, according to circumstances. But still, the
poisons about to be considered form a good natural order when contrasted
with these irritants. For the irritants which possess a double action
are nevertheless characterized by the symptoms of inflammation being at
least their most prominent effects; while the most prominent feature in
the effects of the poisons now to be considered is injury of the nervous
system. It is more difficult to draw the line of separation between the
present class and the pure narcotics; for many narcotico-acrids rarely
cause any symptom but those of narcotism.
The narcotico-acrids are all derived from the vegetable kingdom. Many of
them owe their power to an alkaloid, consisting of oxygen, hydrogen,
carbon, and azote.
The characters which distinguish the symptoms and morbid appearances of
the narcotico-acrids from those of natural disease, do not require
special mention; for almost all the remarks made in the introduction to
the class of narcotics are applicable to the present class also. A few
of the characters, however, which have been laid down, do not apply so
well to the narcotico-acrids as to the narcotics. In particular, it
appears that what was said on the short duration of the effects of the
narcotics does not apply so well to the present class of poisons; some
of which, in a single dose, continue to cause symptoms even of narcotism
for two or three days. But the rule, that they seldom prove fatal if the
case lasts above twelve hours, is still applicable,—at all events they
rarely prove fatal after that interval by their narcotic action. The
poisonous fungi, however, have proved fatal as narcotics so late as
thirty-six hours, or even three days, after they were taken; and perhaps
digitalis has proved fatal narcotically at the remote period of three
weeks. But such cases are extremely rare.
Some narcotico-acids, such as the different species of _strychnos_, are
quite peculiar in their effects; so that their symptoms may be
distinguished at once from natural disease.
Orfila divides the narcotico-acrids into six groups, and this
arrangement will be followed in the present work; but they are not all
very well distinguished from one another.