seems the same, we find that in the course of the second observation five, ten, or even fifteen pulsations have been gained or lost. This form of irregularity of pulse is not peculiar to uræmia, but is common in it, and is inevitably a bad sign. Traced to its cause, it is found to depend on a corresponding irregularity of the respiration, for in nearly all forms of slow narcotic poisoning the heart is obedient to the respiration. The respiration is, from the beginning to the end, irregular and imperfect; there is not dyspnoea, but uncertainty; no obstruction to air, but a destroyed balance in the respiratory move ments. Much has been argued as to the condition of the expired air in uræmia; Frerichs has stated that the breath is largely ammoniacal in this state. Other observers have denied the position. In fact, both are right and both are wrong. The true position is simple. In all persons there is an exhalation of ammonia by the breath, varying in amount. In uræmic persons, in their ordinary health, there is, I believe, always an excess of ammonia in the breath; for in them the lungs are supplementing the kidneys. If, then, in any case there be sudden suppression of the excretory power of the kidneys, there may be an excess of ammonia in the breath. I have unmistakably seen examples where this excess was clearly manifested-so clearly that the exhaled vapour gave distinct fumes to the hydrochloric acid rod, and even changed the colour of reddened litmus. On the other hand, there are cases where the very cause of the development of the acute symptoms lies in the fact that the compensating eliminative function of the lungs has become suppressed: in such state there will be no ammonia found in the breath; it would be a saving clause if the alkali were there. I have but one word more to say respecting the absolute diagnosis. It relates to the degree of consciousness manifested by uræmic patients in the ex treme state. There are periods when the coma is so profound that nothing arouses the sufferer. There are, again, other times when he arouses of himself, or is quite capable of being aroused, and of speaking or attempting to speak, and of sitting up, and of swallowing foods or medicine, and of acting altogether with a considerable amount of intelligence. The symptoms above described, taken in all their entirety, are sufficient to give a correct picture of uræmic disease. But it is worthy of remark that there are special symptoms in different cases which, without removing the idea of the general fact that the arrest of the function of the kidneys is the cause of the symptoms altogether, suggest forcibly either that the poison is different in certain instances, or that, being the same in all, it acts variously in different persons, by difference of dose, or by peculiarity of effect on the individual organism. Thus in one case the pupil may be dilated, in another natural in size; in one patient there shall be active convulsions, in another no convulsion whatever; in one there shall be marked derangement of the bowels, in another no intestinal irritation shall be presented; in one there shall be vomiting as an early symptom, in the next no indication of such an effect. These distinctions, all of import, are nevertheless secondary; since, in every case, they are included in two common symptoms-excretion of albuminous urine, and coma. Differential Diagnosis. Uræmia simulates in some particulars so many of the diseases in which coma is the leading symptom, that an attempt to enter into the distinctions that mark it off from every analogous disorder would be interminable. In some instances, too, the task would be an exceedingly difficult one, unless considerations relating to the previous existence of albuminuria were admitted into the argument. Thus, for example, the diagnosis between uræmic poisoning and belladonna poisoning is so difficult, that, in a case where the history of the patient was unknown until the occurrence of coma, I for one, after having witnessed both classes of toxæmic disease, would scarcely be able to note a trustworthy sign on which to build a decided opinion. It is obvious, in fact, that the poisons producing the two classes of symptoms are well nigh identical in regard to their effects. Here, therefore, we must rest on the course which the symptoms take, and on such occurrences as the vomiting of suspicious matters, for a guide to diagnosis, rather than on any particular or exclusive symptom. From epilepsy, uræmia is distinguished by the tendency to diarrhœa, and, above all, by the suppression of urine. Distinctions may also be drawn at the time of the acute paroxysm; for the convulsion of uræmia is not of the same tonic character as in epilepsy; the asphyxia is not so marked, and the coma is more prolonged. At one time in the history of medicine, uræmia constituted one of the varieties of coma called generically "apoplexy." The unlearned as yet call uræmia apoplexy. From true cerebral apoplexy, however, uræmia is distinguishable by the facts that the skin is less hot, the stertor less marked, the blowing expiration less frequent, the convulsion more defined, determinate, and paroxysmal, and the suppression of urine more certain. From poisoning by opium, uræmia is to be distinguished by the following particulars. In uræmia, the pupils are generally dilated; the patient may become quite sensible during the acute attack, and then profoundly relapse; the bowels are often free; the urine is scanty or absent; the breathing is free from stertor; and the convulsions are active. In opium poisoning the pupil is contracted; the patient remains unconscious, or, recovering his consciousness, remains conscious; the breathing is stertorous; the urine free; and the muscles paralytic rather than convulsed. In fine, in establishing, in a doubtful case, a differential diagnosis between uræmic intoxication and its analogues, we must depend most on the previous history of the patient, and on a correct recollection of the absolute symptoms by which uræmia is manifested. The careful practitioner will then rarely be misled. If, however, a preceding history cannot be gleaned, if the symptoms be obscure, and if urine be not passed by the patient, it is an excellent point of practice to draw off by a catheter the urine that may be contained in the bladder, and test for albu men. The presence of ammonia in the breath, looked on by many as a definitive indication of uræmia, is not, according to my mind, of any peculiar diagnostic value; inasmuch as ammonia is presented in the breath in the natural condition, and is expired in excess in many other diseased states than uræmia: thus, in the coma of typhus and of typhoid fevers, an excessive ammoniacal exhalation from the breath is a common symptom. Further, there are examples of acute uræmia where the ammoniacal exhalation, common to the patient antecedently to the attack, is suspended during the comatose state. Without going so far, therefore, as to say that the presence of ammonia in excess in the breath is not to be taken with other indications as a corroborative sign of uræmia, I should not let it rank as a positive symptom for differential purposes. COMPLICATIONS OF URÆMIA. I have tried, so far, to give the diagnostic history of uræmia in its simple form; but it happens often that there are certain complications which present symptoms delusive in character, and calculated greatly to deceive him who has not his eye on the unities of diseased action. These complications consist generally of inflammatory or pseudo inflammatory outbreaks, ac |