Imagens das páginas
PDF
ePub

urine was not ammoniacal, but had often a feebly acid reaction. The other fact is, that where ammonia is largely administered, its removal by the breath is so rapid and immediate, that no argument as to its elimination or non-elimination by the urine can be satisfactory in the absence of observations as to the condition of the air thrown off in expiration, and of the exhalations from the cutaneous surface. So rapid, indeed, is the elimination of ammonia by the pulmonary membrane, that in an experiment performed and recorded by Mr. Blake, where a drachm of liquor ammonia was thrown into the jugular vein, ammonia was detected in the breath by the acid rod test a few seconds after the operation.

When the serous cavities, as the peritoneal cavity, of the body of an animal are opened directly after death, there is, for a few minutes, a free watery exhalation, which, according to my observation, always contains ammonia. In oxen, after a small opening has been made into the peritoneum, I have several times introduced a microscope glass moistened with acid, protected by a cylinder, (as in the cylinder в, p. 281), into the cavity, and, after withdrawing the cylinder, and carefully drying it and the contained glass slip, have found distinct evidence of the crystalline deposit on both. The coagulation after death of the serous fluid in these cavities may possibly be connected with this evolution.

I infer, then, as will be seen from the preceding, that ammonia is a normal excrete of the animal body. The inference is significant, apart from the mere consideration of the animal organism. It embraces the idea of a further and more intimate connexion between the

animal and the vegetable worlds. We have long recog nized the carbonic acid excrete from man, and the water vapour which he exhales, as deposits in the air bank for the use of plants, and for elaboration by them into new food for the animal itself. To the magic circle ammonia may be introduced, not only as resulting from the decomposition of effete animal matter, but as given off directly from the animal organism.

In the transformations of the animal body, the evolution of ammonia is as necessary an act as its production; and the freedom of its evolution is secured by its volatility, equal diffusion, and easy excretion from every excretory surface. Had a fixed alkali been the blood` solvent, not only would the required amount have been considerable, but the diffusion would have been less subtle, and the elimination less secure, since the arrest of the function of but one organ would lead to accumulation and to the dangers incident thereto.

The consideration of the evolution of ammonia by the body as an excrete, leads also to one or two observations bearing on practical concerns. I have shown that in consumption there is at times an abnormal exhalation of ammonia by the skin, while in some other diseases of a chronic nature there is also an equally abnormal elimination of the alkali by the breath. These cases must be carefully separated from those of the low fever class, in which the free elimination is but the result of superalkalinity. This separation made, the question naturally suggests itself, whether in those chronic cases where the elimination is so free, the fact of the elimination may not be intimately connected with the fact of the debility and waste of substance by which such exhaustive diseases are specially character

ized. It is clear that an evolution of the two elementary representatives, nitrogen and hydrogen, cannot occur in excess, and over above their normal standard, without waste of substance, if the position be correct that such evolution is direct from the blood; and this position seems at once possible and obvious.

Lastly, the evolution of ammonia by diseased persons is suggestive of various hygienic points bearing on the treatment of disease. A number of A number of healthy persons cannot be long entombed in an ill ventilated place, without respiring an air charged, not only with carbonic acid, but with the alkaline emanation in addition. An historian of the Calcutta black hole tragedy, himself one of the sufferers, tells us that what added intense suffering to the prisoners, was the intolerable irritation produced by the inspired air: the sensation being, as he said, as though the face were held over a vessel of hartshorn. In this catastrophe, one hundred and forty-six men were shut up in the dungeon, which was eighteen feet square, open to the west only by two small windows, which were strongly barred, and admitted but a feeble current of air. The difficulty of respiration commenced within an hour after this living interment; and in two hours, fifty were dead. In the morning, only twenty-three remained alive; and it is a matter of great interest, that nearly the whole of these suffered afterwards from putrid fever-evidently our malignant typhus, and many of them died.

Dr. R. D. Thomson has also shown that, in the air of ill ventilated cholera wards, sulphide of ammonium is one of the constituents. I have already indicated that the effect of sulphide of ammonium on animals is to produce symptoms strictly analogous to typhus; and

B B

it is fair to presume that this gas is present not only in the air of cholera wards, but in all badly ventilated hospitals. In a wretched workhouse infirmary, which I had occasion to visit a few times during last year, the roofs of the wards being low, and the whole place a dungeon, the presence of ammonia in the air required no other test than the sense; and I understood that this was a common condition. The treatment of disease in this place was always unsatisfactory.

In these facts, we have set before us, in fuller light, the importance not only of providing free ventilation, but, in fever cases specially, of carefully isolating the patients, and of securing a rapid and complete removal of the emanations from their bodies. In the absence of these precautions, if nature, busy on her part in relieving the system of the poison which is destroying it, be not seconded by the practitioner, treatment must needs be a farce, and a farce the more solemn, as it apes the more profound.

EXPERIMENTS SHOWING

III.

THE EFFECT OF LACTIC ACID

ON ANIMAL BODIES.

WHILST my attention was being directed to the effects of the alkalies, I thought it would be a point of great interest to change the line of experiment, and to inquire into the influence of the acids as administered in moderate and continued doses. I selected for experiment primarily the lactic acid; first, because it is a feeble acid; secondly, because it is an acid of the tissues; and, thirdly, in consequence of the theory advanced by Dr. Prout, and supported afterwards by the arguments of Drs. Todd, Williams, Fuller, Headland, and Mr. Spencer Wells, that lactic acid is the probable materies morbi of acute rheumatic fever.

I premise by stating, that the acid solution used in all the coming experiments contained ten per cent. of the acid itself.

In the first experimental attempts, the acid was given by the mouth, but the results were unsatisfactory; there was a difficulty in the administration, and the effect of the acid was, as I think, destroyed by the digestive process.

I followed up these attempts by trying to throw the acid into the system by the veins; but here two objections came in the way. As the acid came into contact with the blood, it formed with it a slimy semicoagulated mass which prevented injection; and at the same time I foresaw that any effect on the endocardial surface, after such injection, might be reasonably construed as resulting from the direct action of an irritant.

In this dilemma, I turned to the experiment of injecting the fluid, well diluted with water, into the peri

« AnteriorContinuar »