Insensibility, with a scarcely perceptible respiration, although in some cases it is attended with an apopletic stertor; the countenance is livid and cadaverous; the skin cold; and the muscles of the limbs and trunk in a state of extreme relaxation. The pupils are insensible to the impression of light, and the pulse is almost imperceptible. In some stages, the patient, by being strongly shaken, may be roused for a few moments from the lethargy; there is generally a narcotic odour distinguishable in the breath. Vomiting may also take place upon the first impression of the laudanum upon the stomach; although after its action has been displayed upon the brain, it will be difficult to excite emesis by the most powerful means; the reason of which may be very satisfactorily deduced from the ingenious experiments of _M. Majendie_ on the mechanism of vomiting; by which he proves, that without the influence of the brain, the muscles, whose actions constitute an essential part of the operation, are incapable of performing their duty, and that vomiting therefore cannot take place. This is a very important doctrine, inasmuch as it suggests to the pathologist several expedients, by which he may be enabled to occasion vomiting, by recalling the excitability of the brain. The period which will elapse, between the ingestion of the poison, and the death of the sufferer, may be stated to be from six to twenty-four hours; but it will in each case be liable to vary, not only from the quantity of opium swallowed, but from the habit and peculiar circumstances of the individual submitted to its operation. _Physiological action of Opium._ It is still a question for the decision of future physiologists, whether the narcotic principle of opium destroys the functions of the nervous system by a local impression upon the stomach,[421] or by being absorbed,[422] and brought into contact with the brain in the course of the circulation. We are inclined to adopt this latter opinion, and have therefore placed _opium_ in the second division of our classification; at the same time, we think that it may occasionally produce an effect upon the nervous extremities of the stomach, and we have accordingly placed an _asterisk_ against the word, by which we denote this double mode of operation. But, by whatever medium it may act, it is evident that it occasions death by destroying the functions of the brain; in consequence of which the muscles of respiration, no longer supplied with nervous energy, cease to contract, and the animal dies in a state of suffocation.[423] _Of the treatment in cases of poisoning by Opium._