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face of the body. The first indication of convalescence is a desire for food. At least three days elapse before the animal begins to run about healthily; but when recovery is set up it proceeds rapidly, and no ill effects seem to follow.

Such are the general symptoms of an excess of water in the blood; but there are other special modifications in the blood itself possessing great interest. If blood be drawn while the animal is suffering from the effects of the injection, that fluid is found thin, of red colour, and very feebly coagulable. In extreme cases the property of coagulation is lost altogether; and if it be attempted to extract fibrine by agitation of the blood, the experiment fails. Even the coagulation of the albumen by heat is feebly presented. The blood consequently flows with great ease from a wound; and the anæmic hæmorrhagic diathesis is set up. The red corpuscles are much changed; they are greatly enlarged, and assume an oval form. As recovery occurs, these abnormal conditions gradually pass away; but for many weeks the corpuscles retain their diseased outline and character. In a case of extreme anæmia in the human subject, my friend and colleague, Dr. Leared, observed the same modifications in the blood-corpuscles that I have described as occurring in the dog after the production of artificial anæmia and dropsy.

If the symptoms thus induced by the introduction of water into a healthy organism, be compared with those observed in acute uræmia, a certain analogy at once strikes the mind; i. e., there are the same de

cided prostration and coma.

ceases.

But here the analogy There is no period during which the heat

of the body is increased; there are no convulsions; there is no dilatation of the pupil; there is no vomiting; there is no stertor in the breathing; and lastly, there is none of that irregularity of the respiration and circulation which so peculiarly distinguishes uræmic intoxication.

On the other hand, there is one symptom which is exhibited after the injection of water into the organism which is not present in uræmia, or at all events is not necessarily presented; I mean anæmic bruit.

Taking the symptoms, then, as derived from both sources from true uræmia on the one side, and from surcharge of water on the other-we are bound to altogether exclude from the argument the hypothesis of excess of water as the cause of acute uræmia. When we admit that the coma of uræmia is possibly in some cases increased by suppression of mere aqueous secretion, we admit honestly and necessarily an intensifying source of one particular symptom; but we fail to trace anything more than a coincidental fact, even in this concession.

From the consideration of water as a cause of uræmic coma, we pass to urea. Is this a poison, and is it the poison?

The answer to these questions is to be found only by experiment on inferior animals. To solve the question by this means many hands have been employed, and different opinions have been arrived at. An absence of uniformity in the mode of conducting

the inquiries has, I think, led to the differences observed.

Administered by the mouth to an animal, urea can scarcely be called a poison, unless the dose be enormously large. A dog weighing ten pounds takes a drachm of urea with little result; but in rabbits the dose named excites vomiting and convulsion, and sometimes leads to death. Taking it all in all, the method of experimenting by administering the substance by the mouth is most imperfect. In some cases the compound is decomposed in the stomach; in other cases it is in part absorbed into the blood, and passes off by the kidneys; in many instances it is vomited in great portion soon after it is swallowed, or it may pass off by the bowels in a brisk purge; however it is disposed of, it does not definitely and clearly bring out the true uræmic symptoms as they are elicited on suppressing the renal function by extirpation of the kidney.

Administered by direct injection into the veins, urea can be made to induce symptoms essentially uræmic. Dr. Hammond records an experiment in which the injection of five grammes of urea, or 77.17 grains in solution in water, into the jugular vein of a dog weighing 38 pounds, at 10 a.m. produced after the lapse of 45 minutes slight spasms of the muscles of the eyelids, and in 50 minutes severe general convulsion; the convulsions continued for fifteen minutes with great violence, when coma followed and lasted until 6 p.m., when the animal died. There was no excretion of urine after the injection of urea. The breath

was examined every hour for ammonia, but at no time was it detected. It was, however, found in the blood last drawn. There was neither purging nor vomiting. Immediately after death the following post mortem results were yielded :

"The substance of the brain appeared to be perfectly healthy; but there was considerable injection of the vessels of the meninges. The ventricles contained about 15 cubic centimetres of serous fluid. Urea was detected in this by chemical analysis, and by microscopical examination. It was likewise

found in the blood from the sinuses.

"The vertebral canal was laid open, and the spinal cord examined. Its substance presented a normal appearance, but there was some congestion of the vessels of its membranes.

"The chest contained a small quantity of serous fluid. The lungs were congested, but were otherwise healthy. The heart was of normal size, and did not appear to be in the least diseased. It contained a considerable quantity of fluid blood; 100 grammes were collected from it and the large vessels. The urea in this quantity amounted to 0.873 of a gramme.

"Upon microscopical examination of this blood, the red corpuscles were found to present a crenated margin, and to be in decidedly less than the normal quantity. The white corpuscles were very much increased in quantity; as much as in well-marked leucocythemia.

"The cavity of the peritoneum contained a small quantity of serous liquid. The membrane was in places slightly congested.

"The liver was healthy in appearance; but the spleen was considerably enlarged, and contained much more than the normal quantity of blood. The tissue of this latter organ, when examined microscopically, was found to present several important deviations from the normal structure. The Malpighian corpuscles were almost entirely absent, and there was a very great increase in the number of parenchyma cells. These latter were much larger than I (Hammond) have ever found them in the spleen of the dog. The red blood-corpuscles in the splenic blood were generally aggregated in groups, and were of irregular forms.

The stomach was opened, and presented nothing abnormal. The contents, consisting of mucus with a few pieces of bone, were of alkaline reaction, and contained both urea and ammonia, the latter in considerable amount.

"The kidneys were enlarged and very much congested. Upon cutting into them, the blood poured out from innumerable orifices. There was no obstruction to either the renal arteries or veins that was discovered after death. The tissue of the kidneys, when submitted to microscopical examination, showed excessive congestion of the capillaries, and enlargement of the Malpighian bodies. Into many of these latter extravasation of blood had taken place, and the tubes were gorged with this fluid.

"The bladder contained a small quantity of bloody urine."

There are not in every case such decided results, on the injection of urea directly into the circulation,

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