In the microscopical examination of urinary deposits, the observer often meets with substances whose nature and origin cannot readily be determined. This is due in many instances to the presence of bodies which have fallen in accidentally, or which have been placed in the urine for the express purpose of deceiving the practitioner. The importance of recognising matters of an extraneous origin can scarcely be sufficiently dwelt upon, for until the eye becomes familiar with the characters of these substances, it will be obviously quite impossible to derive such information from a microscopical examination of the urine, as will enable the observer to distinguish between those substances whose presence denotes the existence of certain morbid conditions, from certain matters which have accidentally found access, and may therefore be entirely disregarded. Practitioners who use the microscope for investigating the nature of urinary deposits, will derive advantage from subjecting many of the substances referred to in the present communication to microscopical examination, by which their general appearance will soon become familiar to the observer, and he will then be able to recognise them without difficulty should they be met with in the course of an examination of urine.
As most of the undermentioned substances are readily obtained, a brief notice of their characters will be sufficient; the chief object of this communication being to direct the notice of practitioners to the fact of the frequent occurrence of many of them in urine, and to draw attention to those characters in which they resemble, or are liable to be mistaken for, any insoluble constituent of the urine. I may remark that among many substances whose presence is accidental in urine, the following are some of the most important that have fallen under my own notice:—Human hair, cats’ hair, blanket hair, coloured worsted, fibres of cotton, flax, and silk, small portions of feathers, fibres of wood swept from the floor, starch, globules of various kinds, fragments of potato, bread-crumbs, portions of tea-leaves, common house sand, oil globules. Once, a specimen of urine, which had been sent to Dr. Todd for examination, was found to contain several white bodies about half an inch in length, which upon microscopical examination I found to contain tracheae, and they ultimately proved to be larva of the blowfly, although it had been stoutly affirmed that these had been passed by the patient. A few days since Dr. Stewart informed me that a man had brought some urine to him for examination with a thick bright red deposit, which was analyzed by Mr. Taylor, and proved to consist of sesqui-oxide of iron. The urine containing this deposit was of specific gravity 1011, and, upon the addition of ammonia, a broWn flocculent precipitate (hydrated sesquioxide of iron) was thrown down. Dr. Stewart tells me that a considerable quantity of the powder remained suspended in the urine after it had stood for many hours, and that the fluid was still turbid after having been passed through a double filter. The man who brought this urine has also been endeavouring to impose upon my friend Dr. Weber, of the German Hospital.
Hair of various kinds is very frequently found amongst urinary deposits, but, as its microscopical appearance is so well known, it is not necessary to enter into a description of the characters by which it may be distinguished. The varieties of hair most commonly met with are human hair, blanket hair, and cats’ hair; not unfrequently portions of coloured worsted will be found, but the colour alone will often remove any doubts with reference to the nature of the substance. Portions of human hair are sometimes liable to be mistaken for narrow casts of the uriniferous tubes —such as are quite free from epithelium or granular matter, and which present throughout a homogeneous appearance. The central canal in many cases will be sufficient to distinguish the hair from every other substance likely to be mistaken for it, but sometimes this cannot be clearly made out, and the marks on the surface may be indistinct, when attention must be directed to its refracting power, well-defined, smooth outline, and also to the sharply truncated ends, or to its dilated club-shaped extremity in the case of the hair bulb. In these points small portions of hair will be found to differ from the cast, for this latter does not refract so strongly, the lines on each side are delicate but well defined, and the ends are seldom broken so abruptly as in the case of the hair. Cats’ hair can scarcely be mistaken for any urinary deposit with which I am acquainted, and its transverse markings will serve at once to distinguish it with certainty.
Cotton and flax fibres are very often found in urine. When broken off in very short pieces they may be mistaken for casts, but the flattened bands of the former, and the somewhat striated fibres of the latter, will generally be found sufficiently characteristic.
Portions of feathers are often detected in urinary deposits upon microscopical examination, and are derived, no doubt, from the bed or pillow. Their branched character will always enable the observer to recognise them with certainty.
Pieces of silk are not unfrequently present, but these can scarcely be mistaken for any substances derived from the kidney. Their smooth, glistening appearance and small diameter at once distinguish them from small portions of urinary casts, and their clear outline and regular size from shreds of mucus, &c.
Fibres of deal from the floor. Of all the extraneous matters likely to be met with in urine, and calculated to deceive the eye of the observer, none, perhaps, is more liable to be mistaken for a portion of a transparent cast, than a short piece of a single fibre of deal. In hospitals, where the floor is uncovered and frequently swept, portions of the fibres of the wood are detached, and, being light, may be very readily blown into any vessel which may be near. In fact, these fibres enter largely into the composition of the dust which is swept up. I became familiar with the appearance of these bodies for a long time before I ascertained their nature, for, although the peculiar character of coniferous wood is sufficiently well marked, when only very small portions are present, and in a situation in which they would scarcely be expected to be met with, their nature may not be so easily made out. Often only two or three pores may be seen, and not unfrequently these are less regular than usual, in which case they may be easily mistaken for a small portion of a cast with two or three cells of epithelium contained within it. I have very frequently met with these fibres amongst the deposit of various specimens of urine which have been obtained from patients in King’s College hospital.
Starch granules are very commonly found in urinary deposits; usually their presence is accidental, but large quantities of starch have often been added for purposes of deception, in which case their true nature may be discovered, either by their becoming converted into a jelly-like mass on being boiled with a little water in a test tube, by their behaviour upon the addition of free iodine, or by their well defined microscopical characters. The three kinds of starch most likely to be met with in urine, are potato starch, wheat starch, or rice starch. They are readily distinguished by microscopical examination. Small portions of potato, or pieces of the cellular network, in which the starch globules are contained have been occasionally met with. Under the head of starch, may also be included bread-crumbs, which are very commonly present in urine, and have a very peculiar appearance, which may be so easily observed, that a description would appear superfluous. Many of the starch globules will be found cracked in places, but their general characters are not otherwise much altered.
Portions of tea-leaves are occasionally found in urine. The beautiful structure of the cellular portions, and the presence of minute spiral vessels, distinguish this from every other deposit of extraneous origin. A small piece of a macerated tealeaf will be found to form a most beautiful microscopic object.
Milk is sometimes purposely added to urine, in which case there is danger of mistaking the specimen for one of the so-called chylous urine, from which, however, it may be easily distinguished by the presence of small oil-globules, with a well defined dark outline, while the fatty matter in chylous urine is in such a minute state of sub-division, that it only presents a granular appearance under the microscope.
Fatty Matter. The existence of fatty matter in urine is a subject of so much importance to the practitioner, and its accidental presence so frequent, that it may be well to consider the different forms in which it occurs, instead of simply describing the manner in which fat of accidental origin may be distinguished from oily matter, which has been excreted by the kidney. Upon the presence or absence of this deposit often depends the prognosis of a case, and hence it is of the utmost importance to recognise that form which is charateristic of fatty degeneration of the kidney with certainty.
Fatty matter occurs in urine in at least three distinct forms. The first form which I shall notice, is that in which it is met with in certain specimens of chylous urine, and the peculiar milky appearance of the secretion is entirely due to the existence of fatty matter in an exceedingly minute state of division. Upon microscopical examination of such a specimen, all that can be detected is a multitude of minute granular particles, not unlike those of amorphous lithates, scattered all over the field. Upon carefully focussing, it will be observed that each particle is in constant motion, and the movements resemble those met with in chyle and certain other fluids. That these particles are really composed of fatty matter in a minute state of division is shown, by the addition of ether to the urine, which immediately becomes clear; and by the evaporation of the etherial solution, the fatty matter may be obtained in its usual form. From a remarkable specimen of the so-called chylous urine, for which I am indebted to the kindness of my friend Mr. George Cubitt, I obtained as much as 13’9 grains of fatty matter from 1000 of urine; the whole of this large quantity having previously existed in the urine in the minute state of division to which I have just alluded. In such instances, it is clear that from microscopical examination alone, it would be quite impossible to determine the nature of the substance to the presence of which the peculiar character of the urine was due.
The second form in which fatty matter is found in urine is that of globules, each globule consisting of one portion of fatty matter, which either floats freely upon the surface of the urine, or is carried to the bottom in consequence of becoming entangled in some heavier deposit, as for instance mucus, or cells of epithelium. In this case, the oil particles will probably not be very numerous, and they are too large to give to the urine the opalescent appearance, which results from the suspension of fatty matter in a molecular state. The globules appear in the microscope as highly refractive particles, of a perfectly circular form, with a dark and well defined outline. The more minute of these globules present the appearance of a perfectly round black spot. It is in the form of distinct and separate globules that fatty matter is found in urine, when it finds access into that fluid accidentally, as, for instance, if a small particle of butter or a little oil fall into the urine; or if urine drawn off by an oiled catheter be subjected to examination, the oil globules will present this character, and usually they vary very much in size, some being often of considerable diameter.
The third form in which fatty matter is met with in urine, differs from the preceding in this essential particular, that many distinct and separate oil globules, often varying much in size, will be found collected together in the interior of a cell; at the same time, a certain number of free oil-particles may be observed. In a collection of oil particles invested with a cell-membrane, the term “ fat cell ” has been applied, and it is to these cells found in the deposits, and entangled in casts of the uriniferous tubes, that so much attention has been directed of late, in reference to the indications of the existence of fatty degeneration of the kidney afforded by the presence of these bodies in the urine.
Hence by carefully observing the particular character which the oily matter assumes, there is little danger of being mistaken in reference to its origin.
Infusoria and fungi.—After urine has been kept for some time, various forms of fungi, and not unfrequently some infusorial animalcules may be present—vibriones, vorticellæ, and monads are among those most commonly met with, but many other forms are frequently present. The period of time which elapses previous to the development of vibriones and fungi is found to vary very much in different cases; these bodies being sometimes found in urine within an hour after it has been passed, while in other cases the urine may be kept for many days without the development of any animal or vegetable organisms whatever.
Many other matters of extraneous origin frequently forming part of an urinary sediment might be here described, but as most of these will doubtless occur to the mind of every observer, and as their nature is often easily determined, it is unnecessary to enter into further description, which would prolong this paper to too great a length. It is hoped, however, that enough has been said to draw the attention of observers to the importance of the subject, and to point out the necessity of rendering the eye familiar with the characters of many other substances than those which really enter into the formation of urinary deposits, before the microscopical examination of urine can be successfully employed in clinical investigation.
