_Toxic Principle._ Monkshood is very poisonous, and though all parts are toxic the root is the most dangerous, and next the seeds and leaves. The plant seems to vary in toxicity with age and climate, being but slightly active when very young, most active just before flowering, and at the minimum of activity when the seeds ripen. The cultivated form is stated to be much less poisonous than the wild one. Drying removes a part of the toxic substance, and boiling removes most of it. The plant contains the toxic alkaloid _Aconitine_ (C_{34}H_{45}NO_{11}), and also Aconine (C_{25}H_{39}NO_{9}). The root contains 0·17 to 0·28 per cent. of _Aconitine_, but the leaves and flowers less. _Symptoms._ The chief symptoms are those of depression, and are manifested through the nervous system and the circulatory and respiratory organs. Tetanic symptoms are also present. There is loss of appetite, salivation, inflammation of the mucous membrane of the mouth and jaws, grinding of teeth, nausea and vomiting, great restlessness and colic; the animal groans and walks with an uncertain gait owing to bodily weakness, giddiness and paralysis of hind feet or of all limbs; there is also a notable slackening in the pulse, breathing becomes difficult, consciousness is lost and the pupils are dilated. Death ensues in most cases within a few hours, and after convulsions. Kaufmann (quoted by Cornevin) observed in the _horse_ champing of the jaws, salivation, fibrillous contraction of the muscles of the olecranon, then of the buttocks, then of the whole body. The intestinal pains were shown by the blows of the animal’s hind feet under and at the back of the belly. There was also observed an intense and painful contraction of the muscles in the inferior cervical region, the hyoid and the abdomen; an increased sensibility; repeated evacuations; at first congestion, then great paleness of the mucous membranes; diminution in the volume of the arteries; faint whinnyings at the moment of the contraction of the muscles of the neck, shoulders and stomach; muscular rigidity of the posterior limbs; uncertain gait; laboured breathing; and finally paralysis of motion, respiration and senses. Lander in giving similar symptoms for the horse notices also choking movements of the œsophagus, eructation of frothy matter, dilatation of pupils and low temperature. Kaufmann gives the poisonous doses of powdered root for the horse and dog as 13 to 14 oz. and ⅙ oz. respectively. REFERENCES. 4, 16, 63, 78, 81, 128, 130, 153, 161, 170, 203, 205, 213, 233. PAPAVERACEÆ.