The most important are _aloes_, _colocynth_, _jalap_, _gamboge_, _scammony_, _elaterium_, _croton oil_, _castor oil seeds_, various species of _arum_, _euphorbium_, _bryony_, _mesereon_, _physic nut_, and others less commonly known. Dr. Taylor says that aloes and colocynth are the basis of _Morrison’s pills_, which in many instances have induced fatal purging. In _Holloway’s pills_, aloes is the chief ingredient. A favorite remedy with nurses for promoting the catamenia is _hierapicra_, a brown powder consisting of four parts of aloes to one of canella bark. This may give rise to dangerous symptoms. The _symptoms_ induced by these substances are those of irritation of the intestinal canal, severe pain, vomiting, diarrhœa, tenesmus, &c.; followed by collapse, cold sweats, and occasionally convulsions. These effects may also be produced by diseased and decayed vegetables. The _treatment_ must be directed to the removal of the injurious substance by emetics, &c., unless spontaneous vomiting has freely taken place, when it need merely be encouraged by the use of diluents. If the irritant has passed out of the stomach into the intestines it must be carried off by purgatives, especially castor oil. The inflammatory symptoms should be cautiously combated, on account of the great prostration usually caused by these poisons. Opiates, emollient enemata, and fomentations to the abdomen will subsequently be found useful. SIMPLE ANIMAL IRRITANTS. The substances which require consideration under this head, though few, are important. _Poisonous Fish._—Several kinds of fish are constantly poisonous, while some only act injuriously on particular constitutions. The chief effects are sickness and vomiting, irritation of the eyes, depression, and severe urticaria or nettle-rash. In this country the different varieties of shell-fish are those most frequently injurious, especially cockles, mussels, crabs and such-like. _Poisonous Meat._—The flesh of animals which have died of disease has produced serious symptoms when eaten, and has even destroyed life. Several substances, as sausages, cheese, bacon, &c., also become poisonous from putrefaction. The _treatment_ in these instances should consist in the use of emetics, purgatives, and diluents. The vital power must be supported by stimulants, tonics, nutritious diet, &c. CHAPTER XII. IRRITANT GASES. The chief are chlorine, sulphurous-acid gas, nitrous-acid gas, and hydrochloric-acid gas. When diluted, they admit of being inhaled; not so when pure.