CHAPTER XXVI IRRITANT POISONS— (Contd.) II. ANIMAL POISONS CANTHARIDES 0 The Spanish fly (Cantharis vesicatoria) or blister-beetle is | to 1 inch long and J inch broad,, and is distinguished by the shining, metallic green colour of the head, legs and wing-sheaths. Under these sheaths there are two thin, brownish, transparent membranous wings. The powder of its dried body is greyish-brown, and contains shining, green particles. The active principle is cantharidin, C8Hi20 (CO2) O, the anhydride or lactone of cantharidic acid, which is a crystalline body, very slightly soluble in water, but freely soluble in alcohol, ether, chloroform, acetone and fixed oils. It is a powerful vesicant. The non-official preparations made from it are Emplastrum cantharidini (Blistering plaster) and Liquor epfepasticus (Blistering Liquid) containing 0.2 and 0.4 per cent of cantharidin res- pectively. The Indian fly (beetle) which yields cantharidin is known as Mylabris cichorii occurring abundantly in the rainy season in certain parts of North India and Kashmir. It is 1 inch long and about 1/3 inch broad. Its wing sheaths are black, marked with three broad, transverse, orange yellow, wavy bands, which contain scattered black, bristly hairs when viewed under the microscope.1 Mylabris pustulata is another species which yields cantharidin, It is found in the fields of cereals and vegetables in the neighbourhood of Bangalore.2 Symptoms.—Locally applied to the skin, cantharides or cantharidin does not show any sign for two or three hours, and then produces redness and burning pain, followed soon by small vesicles, which later tun together to form one large blister. It may be absorbed by the skin and cause poisoning* Given internally, this substance produces an intense intolerable burn- ing pain in the mouth and throat, quickly extending to the stomach and the whole of the abdomen, and accompanied by difficulty in swallowing, intense thirst, salivation due to the inflammation of the salivary glands, nausea, vomiting containing mucus, blood and shreds of mucous membrane mixed with shining, gregiL-particles, and diarrhoea of bloody stools with tenesmus. These are followed by pain in the loins, distressing strangury, passage of scanty urine containing blood and albumin, painful priapism in the male with swelling and inflammation of the genital organs and frequent seminal emissions, and abortion in pregnant women. The patient becomes extremely restless, with laborious respirations, quick pulse and signs of peripheral failure. In severe cases, headaches, delirium, convulsions and coma usually precede death. Occasionally blisters occur in the mouth and other parts of the digestive tract with which it comes into contact. There are also redness of the eyes and lachrymation. Blood examination may show haernoconcentration, marked leucocytosis and primitive white cells in the peripheral blood. , Fatal Dose,—Twenty-four grains of powdered cantharides (non-official dose, 1/16 to 2 grain) taken in two doses and an ounce of the non-official tincture (tinctura cantharidini, dose, 2 to 5 minims) have caused death; recovery has, however, followed much larger doses. About 1/50 grain8 of 1. Dutt, Ind. Med. Gaz., March 1922, p. 92. 2. Iyer and Guha, Jour. Indian Industr. Science, Vol. XIV-A. Part III 1931, p, 81. 3. C. H. Andrews, Lancet, Sep. 24, 1921, p. 654.