This is the seed of the _Strychnus Nux Vomica_ (Pentandria Monogynia,
_Nat. Ord._ Apocyneæ, _Juss._)
The tree[456] which produces these seeds grows in Ceylon, upon the coast
of Coromandel, and in Malabar. The nux vomica is round and flat, about
an inch broad, and nearly a quarter of an inch thick, with a prominence
in the middle on both sides, of a grey colour, covered with a kind of
woolly matter, but internally hard and tough. The kernel discovers to
the taste a considerable bitterness, but makes little or no impression
on the organs of smell. There is a popular belief that this substance is
poisonous to all animals, except man. Instances, however, are not
wanting to illustrate its deleterious effects upon the human species. It
proves fatal to dogs in a very short period; it has also poisoned hares,
foxes, wolves, cats, rabbits, and even some birds. _Loureiro_ relates
that a horse died in four hours after taking a drachm of the seed in an
half roasted state. Its effects, however, on different animals, and even
on those of the same species, are somewhat uncertain, and not always in
the proportion to the quantity given. With some animals it produces its
effects almost instantaneously: with others, not until after the lapse
of several hours, when laborious respiration, followed by torpor,
tremblings, coma, and convulsions usually precede the fatal spasms, or
_Tetanus_, which so especially distinguishes the operation of this
poison. _Hoffman_ reports the case of a young girl of ten years of age,
who, labouring under an obstinate quartan fever, took, at two doses,
fifteen grains of nux vomica, and died very shortly afterwards. _MM.
Pelletier_ and _Caventou_ have discovered in these seeds, a peculiar
proximate principle, to which their virulence is owing; it was
originally named _Vauqueline_, in honour of the celebrated French
philosopher, but in deference to the opinion of the French Academy of
Sciences, the discoverers have substituted the name _Strychnia_,[457]
because “a name dearly loved, ought not to be applied to a noxious
principle!”
_Strychnia_ is highly alkaline, and crystallizes in very small
four-sided prisms, terminated by four-sided pyramids; its taste is
insupportably bitter, leaving a slight metallic flavour, and is so
powerful as even to be perceptible when a grain is dissolved in eighty
pounds of water;[458] it has no smell. So extreme is its activity upon
the animal system, that in doses of half a grain it occasions serious
effects, and in larger ones, convulsions and death. It is, perhaps, the
most powerful, and, next to _hydro-cyanic acid_, the most rapid of
poisons. _M. Majendie_ has killed a dog with one-eighth of a grain; and
the editor of the _Edinburgh Medical and Surgical Journal_ has seen one
die in two minutes after the injection of one-sixth of a grain into the
cavity of the pleura.
Nux vomica is supposed by _Orfila_ to exert a specific action on the
spinal marrow, thereby producing tetanus, immobility of the thorax, and
consequently asphyxia, of which the animal dies. That this effect is
produced by the absorption of the poison, and its passage into the
circulation, is clearly established by the interesting and important
experiments of _M. Majendie_.[459]