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a marked attack of the disease ever occurs without effusion. The effect of the exudation differs necessarily in different cases; according to the quantity of fluid thrown out, and the place in which it is thrown out, whether in quantity large or small. Thrown into the peritoneal cavity, the alimentary canal, or the pleural cavities, the effused matter may do no more than create a temporary disturbance; nay, it may, for a time, relieve the system from general embarrassment, by securing a removal from the blood of part of the accumulating poison, as well as by relieving the kidney of some amount of congestion. Thrown into the structure of an organ in the direct line of the circulatory stream, the effects of the effusion are much more serious; for now the congestion becomes more imminent, and the all important organs, the lungs, become partners in the evil, in which the brain soon afterwards takes a share. Death may in this way occur from an universal congestion.

Again, the serous effusion may commence in the brain, in the ventricles, or in the subarachnoidean space; and the pressure induced, obscuring first the consciousness, may extend backwards to the medulla, producing embarrassment of the respiration, and the true serous apoplectic state.

These remarks apply to cases where serous effusion only is presented as the result of a general congestion, commencing in the renal organs and reflected from them; but occasionally in patients in whom there is, with a diseased condition of kidney, an

accompanying diseased state of the vessels of the brain, these vessels, very early in the course of the attack, may give way under the pressure, and true sanguineous apoplexy may become allied with uræmic coma as an immediate sequence. Granting, however, that none of these direct complications of the uræmic disorder occur, death takes place, too readily unfortunately, from a more systematic but not less determinate series of causes, which may be summed up as follows.

Firstly: There is the direct toxical effect of the urea, acting by depression on the muscular and nervous systems. Next; there is a direct effect on the vascular organs tending to congestion of their structure, and to embarrassment of the heart and lungs.

Lastly: The blood undergoes physical modifications which render it incapable of supporting the changes which constitute natural life. These modified states of blood, consisting of increase of water, diminution of red corpuscle, modification in physical construction of the remaining cells, and accumulation in the mass of the blood of a true toxic agent, tend to render that fluid incapable of undergoing normal chemical reconstruction in the pulmonic current. Such blood is incapable, at last, of combining with the oxygen of the air; the arterial blood consequently loses its active calorific life-sustaining properties, and the final result is secured by what may be most properly designated apnoea commencing in the circulation.

In every sense, in fine, urea may be considered as a true narcotic poison, resembling to the finest shade, in its modus operandi, the action of those fixed bodies, of which opium is the most fitting type, which, given in such proportions that the system can eliminate them in a moderate period of time, produce merely a passing sleep; but given so as to over-tax the eliminating powers, cause the sleep of death by arresting oxidation.

This last explanation of death is applicable also to many other diseases: to typhoid fever; to snake-bite disease; to cholera; and probably to yellow fever. The patient may breathe freely, but his inspired air is not applied; it is, virtually, as though his lungs were occluded; darkened, congested, comatose, senseless, jactitating or convulsed, he dies taking in air which he cannot apply.

ON THE RELATIONS OF URÆMIA TO FORENSIC

MEDICINE.

There are many cases in which symptoms of uræmia may be confounded, by anyone who is not specially observant, with symptoms arising from a narcotic poison, wilfully or accidentally administered. These cases leading, as they almost necessarily must, to a legal, inquiry, may prove extremely embarrassing, if they are not properly investigated. In a case which I have described in the commencement of this essay, a hasty conclusion might easily have led to the conviction of a man, who, though trespassing beyond the bounds of his knowledge, was yet guiltless of any act

of injury to the woman who placed herself under his treatment. And so also in the instance of the lettercarrier, the symptoms, and even the pathology, would have readily misled an incautious man as to the absolute cause of death. It may be well, therefore, to point out tersely the relation which uræmia may hold to cases of poisoning by common poisonous agents.

In so far as symptoms are concerned, uræmic coma and convulsion are closely allied with the coma and convulsion incident to belladonna. I have pointed out the distinctions which apply to the diagnosis between these two forms of disease at page 155.

Uræmic poisoning may also be confounded with the effects produced by opium administered in a fatal dose. The difference in respect to symptoms may be gathered also from a preceding page (156); but here, after absolute death, one other differential point may be brought into play with effect; I mean, of course, the institution of analysis for the detection of opium in the tissues.

Difficulties again might arise with regard to those poisons which produce not merely narcotism, but irritant effects on the alimentary mucous surface. Such poisons as veratria, conium, hellebore, and even colchicum, might be included under this description, and indeed the whole class of narcotico-acrid poisons. As the tests for these poisons, moreover, are doubtful, the difficulty of distinguishing between their action and the action of urea would be, or at all events might be, alarmingly great. The nearest

approach to accuracy in any such doubtful instances will be obtained by a careful comparison between the symptoms and pathology actually presented, and the symptoms and pathology of acute uræmia in its simplest and most absolute type. The absolute symptoms of acute uræmia, and the pathology, have been already supplied, at pp. 152-55, 158-65.

Uræmia might be confounded with the symptoms arising from the cyanides, such as the cyanide of potassium, a substance which is now becoming so common a poison for the suicide. Truly, in most cases where this cyanide is taken, the death is so rapid, and the chemical pathology so marked, that uræmia would scarcely be considered as, by possibility, connected with the event. But occasionally cases occur in which, the dose of cyanide taken being small, a slowly developed class of symptoms are set up which, in many respects, are allied to the symptoms of uræmia. In the Deutsche Klinik, No. 13 for 1860, Dr. Huseman records an instance in which a healthy man, twenty-one years old, after taking a gulp of a solution of cyanide of potassium, fell prostrate, but, vomiting spontaneously, was restored from immediately impending death. Afterwards he suffered from giddiness, disturbance of mind, coldness, incapability of rising without falling afterwards, and difficulty of respiration; the mouth of the patient was open, the face dark and cyanotic, the eyes fixed, the pupils dilated, and the action of the heart feeble. Sensibility was decreased over the whole body, but there was no spasm. There was no smell of prussic

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