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Full text of "Medical Jurisprudence And Toxicology"

CHAPTER XXXIV

PERIPHERAL   (NEURAL)   POISONS

CONIUM MACULATUM   (COMMON OR SPOTTED HEMLOCK)

This plant belongs to N.O. Umbelliferae, and grows generally in hedge-
rows and in waste places in Europe, America and the temperate regions of
Asia. It has a peculiar mousy odour which is intensified by rubbing the
leaves or other parts of the plant in a mortar with a little solution of caustic
potash or soda. The plant owes its poisonous properties to the liquid alka-
loids, Coniine and Methylconiine. It also contains a crystalline alkaloid,
Conhydrine, allied to methylconiine, and Conic acid.

Coniine, CsH17N.—This exists in all parts of the plant, but is extracted
chiefly from the fruit and leaves by distillation with soda. It is a colourless,
volatile oil, but changes to brown on exposure to air. It has an acrid, bitter
taste and a penetrating mousy odour. It is slightly soluble in water but
freely in alcohol, ether and chloroform. Its salts are stable and crystalline,
and are soluble in water and alcohol. It paralyses the motor nerve endings
and subsequently the motor centres.

Methyl-Coniine, CsHieN.CHs-—This is a colourless, volatile, oily, liquid
alkaloid, possessing an odour similar to that of coniine.

Symptoms.—Burning sensation in the mouth, constriction of the throat,
profuse salivation, nausea, vomiting, dizziness, headache, staggering gait,
weakness or paralysis of the extremities, great prostration, dilated pupils,
ptosis, convulsions and coma. Death occurs from paralysis of the respiratory
muscles. The intellect remains clear to the last.

Fatal Dose.—Uncertain. Half to one grain of coniine is likely to cause
serious symptoms, and 2 grains will probably prove fatal.

Fatal Period.—Death has occurred in a few minutes. The usual fatal
period is one to three hours, though death may be delayed several hours.

Treatment.—Give emetics or wash out the stomach after giving tannic
acid or vegetable astringents. Administer strychnine hypodermically, and
then give general stimulants, such as strong coffee, alcohol, etc. Perform
artificial respiration and administer by inhalation oxygen with 7 per cent
carbon dioxide, if necessary.

Post-mortem Appearances.—Not characteristic. The mucous membrane
of the stomach may be reddened and ecchymosed. The other organs are
congested with venous engorgement and dark fluid blood. The lungs may
sometimes be cedematous*

Tests.—1. Coniine is recognized by its mousy odour. A drop of coniine
dissolved in just sufficient cold water has a clear appearance, but becomes
turbid on heating and again becomes clear on cooling.

2.    Alloxan produces a purple-red colour, which forms white needle-
shaped crystals on standing.   These crystals, touched with caustic potash,
turn purple and give off a mousy odour,

3.    Warmed with sulphuric acid and potassium bichromate, coniine pro-
duces butyric acid, which is known by its peculiar odour.

Medico-Legal Points.—Poisoning by conium maculatum is very rare in
India. In Europe and America accidental poisoning has occurred from the
leaves having been made into salad in mistake for parsnip, or from the root
having been used for parsely, fennel and asparagus. Children have also
been poisoned from using whistles made of its stem. The seeds have been