URINE IN DISEASE.
With respect to the urine of the human subject, it has been shown that considerable variation occurs in health according to the modifications which may have been made in diet. The urine of the lower animals is doubt less, to a certain extent, amenable to the same rule. We observe also striking differences in the urine of herbivora fed on similar diets, as has been noticed above in the case of the horse and the ox, both graminivorous animals and fed nearly alike for experiment, but whose urine showed, on analysis, very marked and important differences. This variation in the result of the digestive process would appear, in such case, to depend upon the internal arrangement of the chylopoietic organs, and should perhaps more especially be attributed to differences in the minute anatomy of the mucous secreting surfaces. Certain fixed variations, then, are to be observed in the constitution of the urine as results of differ ence in healthy anatomy ; and so in the same way, when certain organs are affected by dis ease, we find a set of changes occurring in the urine quite as marked in character ; and it is of especial moment to the physician that he should be able easily and accurately to appreciate them. While studying those conditions, it is however of the highest im portance that the changes which diet, the temperature to which the body may have been exposed, the amount of moisture in the air, &c., should be considered, and that the physician should be able to separate in his mind those phenomena which are indicative of morbid change in important organs, from such as may merely be the results of actions occurring in perfect health, and consistent with its preservation.
Many pathological conditions of the urine are indeed closely simulated by the unim portant changes to which I have alluded. Thus the urine of diabetes insipidus, often a most severe and unmanageable disease, can scarcely be distinguished from that occasionally secreted by healthy persons exposed to cold or moisture, or both, without sufficient exer cise to maintain the full amount of cutaneous exhalation. Such a specimen, were it ex amined carelessly, or allowed to guide the judgment without due attention to con comitant circumstances and previous history, might lead (and I may say has led) to mis takes both injurious to the patient and vexa tious to the practitioner. .
In studying the pathology of the urine, it is also especially important that we should not give undue regard to chemistry, nor be led astray by theories and generalisations such as that fascinating science so constantly would tempt us to enter upon. It must be
remembered that in most cases chemistry as yet only assists us in the detection of symp toms, and in the present state of our know ledge can only thus far serve us, but must fail as a guide to a true knowledge of diseased action or appropriate methods of treatment. This consideration, however, is far from de pressing to those who regard the subject in a truly philosophical spirit; for be it remem bered that when we have detected sugar or albumen in the urine, and when the modes of examination are rendered both easy and exact by chemical labour, we have reaped a most va luable advantage by becoming acquainted with a symptom, without which, we should have been left in such a position that we might have despaired of ever obtaining an insight into the pathology of two most important diseases. A knowledge of symptoms thus acquired by chemistry at once enables us to make use of a large amount of valuable information derived from experience, and to bring to our assistance remedies which would not other wise have suggested themselves, or perhaps have been considered inapplicable. It has unfortunately too often been attempted to push chemical reasoning to the uttermost in considering urinary diseases ; and there is a class of persons, greatly increasing in the present day, who have thus inflicted much mischief on a science which requires great labour in its prosecution, and consequently is the more eagerly condemned as useless by the idle or ungifted practitioner. If we con fine the application of chemistry, in urinary disease, merely to symptotnatology, it is easy to show that we are deeply indebted to the science, and it is the especial duty of those who are most conversant with it to regard its further application with great jealousy.
I shall now proceed to describe the urine as it appears in various diseased conditions of the body, beginning with those from healthy constitution characterised by the existence of deposits of various kinds known as urinary deposits. It is not, how ever, within the province of this article to enter upon any pathological considerations relating to these abnormal conditions.