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mutual attraction. On January 11th, a dose of half a drachm of the carbonate was given, and proved final. A few minutes afterwards, the animal rolled on his side, became convulsed, with opisthotonos, and died.

In another experiment, conducted by myself, a female guinea-pig was placed in a chamber containing 3,350 cubic inches of space, the air of which was kept constantly charged with ammonia vapour. The symptoms produced were very remarkable, and indicated, perhaps as clearly and succinctly as can be desired, the influence of the long continued effects of the volatile alkali on the animal organism.

The experiment commenced on January 19th, 1857; provision was made for the easy introduction of food into the chamber, and also for renewal of the air in a steady stream. From the 19th to the 21st, the animal lived in the vapour without presenting any signs of distress or danger. The only peculiarity was, that her craving for food increased, and that she devoured ravenously all vegetable matter. On the evening of the 21st she was removed from the chamber. She was warm and lively. A little blood drawn from her nose was rather more dusky than natural; and the corpuscles were irregular in form, some being serrated at the edge, others many-sided. They continued for a long time in motion between the glasses, and their force of aggregation was feeble. The blood coagulated in two minutes.

The animal was again placed in the chamber. The

times of supplying the ammonia were made the same; but the amount of ammonia supplied was increased doubly. At first the vapour excited some irritation of the nostrils, but this effect soon wore off. On January 23rd, the animal became restless, and her breathing was quick and feeble. She took her food ravenously, and seemed as if she wished to be constantly eating; the instinctive desire for vegetable food was predominant. The blood, examined day by day, showed further modification of the corpuscles. A perfect corpuscle was not to be met with. The blood rather dried on the glass than coagulated; and the fibrous net-work was scantily developed. The experiment was rigidly carried on for several days: the ravenous appetite continued, the animal slept well, and there was little variation in the other signs until January 30th. At this date she became very feeble; she reclined on the side in part, and was for the first time unusually sensitive to sounds. The merest noise, a scratch on the side of the chamber, or any rustling sound, at once startled her and made her uneasy. This day she refused milk, but sought more ravenously after green food. In the evening of this day her sight also must have become disturbed; for when food was put into the chamber, instead of going to it at once in her usual way, she

sought about for it, When it was placed

without being able to find it. under her nose, she ate cabbage leaf with great eagerness. Left quiet, but watched at a little distance, she was seen to recline a little on the left side, and to remain for several hours in a half comatose

state with the ears involuntarily twitching, the limbs occasionally starting, and the breathing sharp and spasmodic, as in singultus. On removing her from the box, the tongue was found dry, the breathing hurried, and the heart-beat feeble, quick, and irregular. When the hand was placed over the back, all the muscles were felt to be tremulous, and now and then the body was momentarily drawn up by a feeble spasmodic movement.

The blood-corpuscles were now so much modified, that it seemed a marvel how the animal could exist. On the ammonia vapour being removed, however, the serious symptoms quickly passed off. The ammonia was given less frequently, but was occasionally repeated in full dose for two or three days, and always with a repetition of the same train of symptoms. Once I carried on the administration till complete coma was produced, and afterwards exposed the animal freely to air. At the end of two hours the signs of recovery commenced.

On February 28th, the administration was altogether withdrawn, and the animal was allowed to run about as usual. The desire for food, especially for green food, was most extraordinary. In a week she seemed as lively and as well as ever, but the bloodcorpuscles did not lose their irregularity for several weeks. It was as curious as instructive to watch the process of repair in those little floating cells. Their restoration was coincident with, if not dependent on, a restoration of the plasticity of the liquor sanguinis. Towards the end of April, but not until then, the

blood assumed its normal attributes. The corpuscles were natural in size, shape, and power of aggregation; the colour of the blood was bright on exposure to air; and the fibrous net-work was well defined.

The extreme effects of the volatile alkali on the human subject are not commonly seen in this day. I think I have once observed toxic symptoms from the administration of carbonate of ammonia, and they certainly were not the symptoms of uræmia. Referring back, however, to the past history of medicine, we are enabled largely to widen our experience on this point; for soon after the carbonate of ammonia came into use as a medicine, its virtues, in a variety of cases extremely unlike in character, were so lauded that it was pushed to an extreme degree, and even dangerous effects resulted from its employment. The justly distinguished Huxham was amongst the first to criticise these proceedings, and to indicate that, as the tendency of the volatile alkaline salts, and indeed of all alkaline bodies, is to the dissolution of the blood-corpuscles and the establishment of fluidity, so in cases where the tendency of the disease is to the production of identical changes, the use of the alkaline salts as the remedies can be but an addition of evil to evil. In corroboration of his judgment in this respect, he quotes various examples of the toxic influence of the alkalies; one of which, as unique in its kind, and as bearing directly on our present studies, I shall quote.

A young gentleman of fortune came under the care of Dr. Huxham, owing to symptoms he had in

duced on himself by a singular fancy. He had habituated himself to the use of great quantities of the volatile salt, such as ladies use for smelling at, and at length would eat the salt as other people, quoth our author, "eat sugared carraway seedsa Apiμvpayeia, with a vengeance!"

The result was that he brought on a hectic fever, with severe hæmorrhages from the intestines, nose, and gums; every one of his teeth fell out; he could eat nothing solid; he wasted greatly in his flesh; his muscles became soft and flabby; he broke out all over his body in pustules, which itched intolerably; and his urine was excessively high coloured, turbid, and fœtid. With difficulty he was at length persuaded to leave off his pernicious habit; and under the influence of fine and generous wines, asses' milk, and acidulated juices, he lived for several months, but died ultimately as from marasmus."

We have thus traced, on direct evidence, the chronic symptoms excited by ammonia on the inferior subject and on the human subject. Comparing these with the symptoms of uræmia, we fail in tracing the identity as signally as we failed to trace an identity between the acute symptoms of ammoniacal poisoning and those of uræmia. Briefly to sum up the facts, the chronic effects produced by the ammoniacal poison are those of typhus or yellow fever, rather than of uræmia; there is no paroxysmal convulsion of muscle, but jactitation; there is hæmor

* A Dissertation on the Malignant Ulcerous Sore-Throat. By John Huxham, M.D., F.R.S. London: 1757. J. Hinton.

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