Opium is a general paralyzer to muscular fibre, both of the voluntary and involuntary kind, but particularly of the latter. And the only reasonable attempt that can be made to explain the action of Opium in producing constipation, is by a reference to this its paralyzing influence on the coat of the bowel, taken in conjunction with the torpid condition of the general system, and suspension of the animal functions, produced by the secondary action of this Narcotic on the nervous forces. A considerable dose of Opium produces contraction of the pupil of the eye. A larger dose causes coma. The Deliriant Narcotics, _i.e._ Hyoscyamus, Belladonna, and Stramonium, dilate the pupil, and in large doses cause delirium. Their action is thus readily distinguished in cases of poisoning. Opium is the best internal remedy in all cases of pain and nervous irritation, except where contraindicated by great febrile excitement, by stomach irritation, or by cerebral congestion. It acts powerfully on children, and should be administered to them very cautiously, or not at all. It is given to lessen the secretion in some cases of diarrh[oe]a. It is generally unadvisable to give it when there is constipation or hepatic congestion. In wakefulness, mania, and delirium, when unattended with congestion of the brain or fever, it is highly serviceable. In spasmodic disorders, convulsions, and cough, it is more or less applicable. That the active principles of Opium are absorbed, and pass into the blood, has been proved by their detection in the urine. (p. 223.) It does not act on the system before time has been allowed for this absorption. If taken by a mother during suckling, it may act upon the infant by passing into the secretion of milk. It acts upon the nervous system, and probably on the muscles also (_see note_, p. 224,) through the medium of the blood. As a Diaphoretic in fevers and inflammations, Opium is to be preferred in cases where the skin is already moist and cool, where the pulse is soft, and the tongue not coated. But where there is febrile excitement, Antimony, or Ipecacuanha, is rather indicated. Opium may act on the glands of the skin as a true Eliminative; or it may possibly operate in the same indirect way as a nauseant dose of Tartar Emetic, relaxing the ducts of the sudorific glands by its paralyzing influence on their muscular fibre.