ABSTRACT
We suppose at the present day that there are few properly-educated medical men who would deny the value of the stethoscope as a means of ascertaining the presence of disease. The man who would be hardy enough to forego its use would run the hazard of even popular neglect for his temerity. This is not, perhaps, the case at present with the microscope, but we feel sure that whatever argument could be advanced in favour of the stethoscope, as a means of diagnosis, might be urged with tenfold force in favour of the microscope. The stethoscope, in fact, only facilitates the use of the organ of hearing; whilst the microscope widens and extends the power of vision, and creates a new world of observation. By it that which the unaided mind could only imagine, or vaguely indicate, as a probable existence, is demonstrated, and the structure, which was a puzzle and a mystery, becomes perfectly understood. This instrument has now become a necessity for the anatomist and physiologist ; no structure can be truly investigated, no function perfectly understood, without its aid. If, therefore, a knowledge of disease can only be obtained by a knowledge of the structure and functions of the body in health, it is necessary that those who undertake to treat disease should be conversant with the results of microscopic research. The microscope, in fact, should be put into the hands of every medical student, and he should be expected to be as well acquainted with the results of its use as he is of the scalpel, the test-tube, the stethoscope, or any other means of investigation. We fear this is not the case, and that many a young man passes his medical curriculum without even the inquiry being made as to whether he is acquainted with the powers of this mighty instrument of research. We are glad, however, to find that the means of microscopic instruction are multiplying. In many of our medical schools demonstrations with the microscope are given, our medical journals devote some portion of their space to micrological discussions, and here we have a professor in one of our metropolitan medical colleges, writing a book on the microscope especially adapted for medical students. We give Dr. Beale’s remarks on the value of the microscope as a means of diagnosis, entire.
“It may be well ‘here briefly to refer to a few of those instances in which the microscope is known to have afforded valuable aid to the practitioner in the diagnosis of disease.
“Diseases of the Kidney.—There is no class of diseases in which its powers have been more advantageously brought to bear by the practical physician, than in those of the kidney. By a microscopical examination of the urine, we are frequently enabled to ascertain the nature of certain morbid changes which are going on in the kidney, and even to distinguish, during life, the existence of certain well-defined pathological conditions of that organ. The laborious researches of Dr. Johnson have shown us how, by the peculiar character of the casts (fig. 1) of the uriniferous tubes, which are found in the urine, we can ascertain whether the epithelium be desquamating, or, on the other hand, whether it presents no such tendency, but remains firmly attached to the basement membrane of the tube. If the epithelium be undergoing that peculiar change termed fatty degeneration, we shall often be able to ascertain the fact by examining a specimen of the deposit from the urine by the microscope. So again, by the presence of certain other deposits, and a knowledge of the symptoms usually associated with them, the physician is enabled to direct his attention, as the case may be, to the existence of local changes, affecting some part of the genito-urinary mucous membrane, or to more general disturbance, in the changes which take place in primary and secondary assimilation.
“Fatty Degeneration.—Of late years, the remarkable changes which take place, and which have been described under the name of fatty degeneration, in some of the highly complex textures of the body, in consequence of which their properties become changed, and their functions impaired, or altogether destroyed, have been undergoing careful investigation by a vast number of highly-talented investigators.
“The recent discovery of a state of fatty degeneration affecting the arteries of the brain (fig. 2), in the majority of cases of apoplexy, by which the strength of their coats becomes deteriorated, and their elasticity entirely destroyed, would tend to lead us to infer, that this disease is dependent rather upon complicated changes affecting nutrition, than upon the presence of a condition of plethora or hyperæmia, as was formerly supposed, and acted upon.
“The connexion between fatty degeneration of the margin of the cornea (arcus senilis), and similar changes taking place in the muscular tissue (fig. 3), of the heart (a been carefully investigated by Mr. Canton), or in the cerebral vessels, must be regarded with great interest by every practitioner.
“The microscopical examination of the matters vomited in certain cases, has proved to us that the presence of minute fungi, originally discovered by Professor Goodsir, and named by him Sarcinæ Ventriculi (fig. 4), occurs in connexion with certain morbid conditions of the stomach. These remarkable cases are much more frequently met with than was formerly supposed, and form an exceedingly interesting class of diseases.
“Tumours and Morbid Growths.—The microscope has many times afforded important aid in the diagnosis of tumours, although it has certainly failed in many instances ; which circumstance has been brought forward by some as an argument against its employment altogether. After careful microscopical examination, the best observers have failed in deciding as to the nature of a particular tumour submitted to examination ; and they have been unable to pronounce as to its malignant or non-malignant character. On the other hand, not unfrequently this question has been positively and correctly answered in the affirmative or negative, and therefore it would surely not be right altogether to discard the use of an instrument which, although eminently useful in many instances, is not infallible ; for it would appear to be the opinion of some, that the use of the microscope ought to be altogether abandoned, in the diagnosis of tumours. We shall have to return to this important question at a future time.
“For the discovery of Imposition, the microscope is invaluable, as it almost necessarily follows that, in consequence of the frequency with which urine is subjected to minute investigation, patients often resort to various expedients to deceive the practitioner. Perhaps flour, starch (fig. 5), sand, and milk, are more frequently employed for this purpose than any other substances. The microscope will obviously enable any one to detect the first three. If milk be added to urine, the mixture may very readily be mistaken for a specimen of the so-called chylous urine. Although a considerable quantity of fatty matter is present, in either case, this fatty matter exists in a very different state. In milk, we find the oil-globules (fig. 6), so characteristic of this fluid, while, in true chylous urine, not a single oil-globule can be found, although the specimen may contain a large quantity of fatty matter in a molecular state (fig. 7).
“Larvas of the Blow-fly in Urine.—A specimen of urine containing several bodies of about half an inch in length, and of a rounded form, was once sent to Dr. Todd for examination. The bodies in question looked not unlike the larvæ of some large fly, but, as it was confidently affirmed that they were passed by the urethra of a gentleman, the accuracy of this view of their nature was doubtful.
“Upon placing a portion of one of them under the microscope, tracheæ (fig. 8)—(the air-vessels characteristic of the class of insects) were observed in considerable numbers ; and this circumstance alone enabled me to say positively that they were not entozoa, and that they could not have been passed in the manner stated. They were afterwards proved to be the larvæ of a fly.
“The claws of echinococci and portions of hydatid cysts have on several occasions been discovered in the urine, sputa, &c., upon submitting portions of these fluids to microscopical examination, proving beyond a doubt the existence of hydatids.
“Substances passed by the Bowels.—If the practitioner have a good knowledge of the use of the microscope, he can often ascertain the nature of substances passed from the alimentary canal ; and, by the aid of this instrument, he can often at once decide as to the nature and origin of substances, which, to the unaided eye, only present most doubtful characters. Considerable perplexity has arisen from the presence of bodies in the stools of patients, which afterwards proved to be portions of almonds, gooseberry skins, portions of potato, the testa of the tamarind, husks of wheat, &c. : not many years ago the uredo of wheat was mistaken for, and described as, a peculiar fungus, to which it was supposed the phenomena observed in cases of cholera were due.
“Portions of vessels which, unlike the other constituents of the food, have resisted the process of digestion, have been met with in the fæces, and mistaken for small intestinal worms, which they much resemble when examined by the unaided eye. Upon being subjected to microscopical examination their true nature was readily discovered.
“In Medico-legal Inquiries the microscope has often afforded valuable aid. The distinction between blood spots and red stains produced by fluids resembling blood in colour,—between human hair and that of animals,—and the detection of spermatozoa in cases of rape, need only be adduced as examples of the importance of the microscope in such investigations.
“Far detecting Impurities in Food and Drugs the microscope has afforded important aid, and there are several other purposes to which it may be applied, some of which will come under consideration in a subsequent chapter.”
These are some of the positive uses of the microscope in the investigation of disease, uses which ought at once to arrest the attention of the mere “practical man,” but its importance is even greater in those instances where it corrects our theories of life and disease, and thus becomes the means of modifying a whole system of practice. It is thus that it lays the axe at the root of spurious systems of medicine, and is certain to bring about the destruction of all absurd generalizations, whether they go by the name of homœopathy, hydropathy, or more legitimate terms.
We give one other extract as a specimen of Dr. Beale’s book. It relates to a class of substances, of which there is, at present, much to learn both in health and disease :—
“Creatine—Creatinine.—Creatine exists only in very small quantity in muscular fibre. According to Dr. Gregory, it is most readily prepared from the flesh of the cod-fish ; from 25 lbs. of which, in one experiment, he obtained 164 grains of creatine. The flesh is to be chopped in small pieces, and well kneaded with water. After all the fluid has been expressed by powerful pressure, it is very carefully raised, to the boilingpoint, and the coagulated matter removed by filtration. The phosphatic salts are precipitated by caustic baryta. The solution must be again filtered, and evaporated at a gentle heat (130°-140°) to about one-twentieth of its volume, or to the consistence of syrup ; any scum which forms being, from time to time, removed from the surface. This concentrated solution may then be set aside. On cooling, it forms a thin jelly, and, after standing for some time, crystals of creatine are deposited.
“Crystals of creatine are represented in fig. 216, and those of creatinine in fig. 217, which have been copied from M. Robin’s Atlas (see 272).
“Liebig obtains creatine and creatinine from urine, by evaporating the fluid, after the precipitate produced by the addition of lime-water and chloride of calcium has been separated by filtration. During evaporation, the greater part of the salts are deposited, and the mother-liquor is treated with 1-24th of its weight of chloride of zinc : after some days round granules separate; these are composed of a compound of chloride of zinc and creatinine, with which the creatine is mixed (fig. 218). The granules are dissolved in boiling water, and treated with hydrated oxide of lead, until the reaction becomes alkaline. The fluid is next filtered, decolorized with animal charcoal, and evaporated to dryness. The residue consists of creatine and creatinine, the latter of which may be removed by boiling alcohol, in which creatine is almost insoluble.”
We cannot speak more highly of Dr. Beale’s book than to say that we should be glad to see a copy in the hands of every medical student and every medical practitioner in the kingdom. Those who have employed the microscope will find it of great assistance, whilst those who have not yet commenced the use of this instrument cannot fail, we should think, by the perusal of a volume like the present, to be convinced of its importance in the investigation of disease. The work abounds with beautifully executed wood-cuts, and is got up in the best possible style.
