_Symptoms._--Vomiting, purging, tenesmus, etc., followed by cold sweats, collapse, or convulsions. _Post-Mortem Appearances._--Inflammation of alimentary canal; ulceration, softening, and submucous effusion of dark blood. _Treatment._--Diluents, opium, stimulants, abdominal fomentations, etc. Certain of these irritant poisons exert a marked influence on the central nervous system, as the following: =Laburnum= (_Cytisis Laburnum_).--All parts of the plant are poisonous; the seeds, which are contained in pods, are often eaten by children. Contains the alkaloid _cytisine_, which is also contained in arnica. It has a bitter taste, and is powerfully toxic. Symptoms are purging, vomiting, restlessness, followed by drowsiness, insensibility, and convulsive twitchings. Death due to respiratory paralysis. Most of the cases are in children. Treatment consists of stomach-pump or emetics, stimulants freely, artificial respiration, warmth and friction to the surface of the body. =Yew= (_Taxus baccata_) contains the alkaloid _taxine_. The symptoms are convulsions, insensibility, coma, dilated pupils, pallor, laboured breathing, collapse. Death may occur suddenly. Treatment as above. Post-mortem appearances not characteristic, but fragments of leaves or berries may be found in the stomach and intestines. =Arum= (_Arum Maculatum_).--This plant, commonly known as 'lords and ladies,' is common in the woods, and the berries may be eaten by children. It gives rise to symptoms of irritant poisoning, vomiting, purging, dilated pupils, convulsions, followed by insensibility, coma, and death. Many plants have an intensely irritating action on the skin, and when absorbed act as active poisons. =Rhus toxicodendron= is the poison oak or poison ivy. Poisoning by this plant is rare in England, though not uncommon in the United States. Mere contact with the leaves or branches will in many people set up an acute dermatitis, with much oedema and hyperaemia of the skin. The inflammation spreads rapidly, and there is formation of blebs with much itching. There is often great constitutional disturbance, nausea, vomiting, diarrhoea, and pains in the abdomen. The effects may last a week, and the skin may desquamate. =Primula obconica= is another plant which, when handled, gives rise to an acute dermatitis of an erysipelatous character. The face swells, and large blisters form on the cheeks and chin. XXIX.--OPIUM AND MORPHINE