nown to kill both adversaries. Although
thus highly poisonous, the bean has nothing in external aspect, taste or
smell to distinguish it from any harmless leguminous seed, and very
disastrous effects have resulted from its being incautiously left in the
way of children. The beans were first introduced into England in the year
1840; but the plant was not accurately described till 1861, and its
physiological effects were investigated in 1863 by Sir Thomas R. Fraser.

The bean usually contains a little more than 1% of alkaloids. Of these two
have been identified, one called _calabarine_, and the other, now a highly
important drug, known as _physostigmine_--or occasionally as _eserine_. The
British pharmacopoeia contains an alcoholic extract of the bean, intended
for internal administration; but the alkaloid is now always employed. This
is used as the sulphate, which has the empirical formula of
(C_{15}H_{21}N_3O_2)_2, H_2SO_4, plus an unknown number of molecules of
water. It occurs in small yellowish crystals, which are turned red by
exposure to light or air. They are readily soluble in water or alcohol and
possess a bitter taste. The dose is 1/60-1/30 grain, and should invariably
be administered by hypodermic injection. For the use of the oculist, who
constantly employs this drug, it is also prepared in _lamellae_ for
insertion within the conjunctival sac. Each of these contains
one-thousandth part of a grain of physostigmine sulphate, a quantity which
is perfectly efficient.

Physostigmine has no action on the unbroken skin. When swallowed it rapidly
causes a great increase in the salivary secretion, being one of the most
powerful _sialogogues_ known. It has been shown that the action is due to a
direct influence on the secreting gland-cells themselves. After a few
minutes the salivation is arrested owing to the constricting influence of
the drug upon the blood-vessels that supply the glands. There is also felt
a sense of constriction in the pharynx, due to the action of the drug on
its muscular fibres. A similar stimulation of the non-striped muscle in the
alimentary canal results in violent vomiting and purging, if a large dose
has been taken. Physostigmine, indeed, stimulates nearly all the
non-striped muscles in the body, and this action upon the muscular coats of
the arteries, and especially of the arterioles, causes a great rise in
blood-pressure shortly after its absorption, which is very rapid. The
terminals of t