MICROSCOPE, USES OF THE. 



MICROSCOPE, USES OF THK. 



content* ; while, on the other hand, It placed in water, they become 

 sph'rica] from endotmosis, and ultimately bunt. It u not difficult 

 to make a rotation of similar density to that in the interior of the 

 oorptucle ; and in thu manner, as Dr. Rees expresses it. We may take 

 the specific gravity of a blood-corpuscle, if we ascertain the specific 

 gravity of the solution which baa been added to the blood. 



Acetic acid causes the membrane of the corpuscle to become more 

 transparent and clear, and to swell up from endosmosis. After the 

 application of thii reagent the blood corpuscle maybe scarcely visible, 

 but the membrane U not dissolved by it Strong hydrochloric and 

 nitric acids do not dissolve the globules ; with the latter reagent the 

 outline is often rendered darker and thicker, while the entire globule 

 becomes smaller. The corpuscles are entirely soluble in ammonia 

 and alkalies. They are rendered darker, and the walls corrugated, by 

 the acid of the gastric juice, and after remaining in acid urine for 

 some time a similar change occurs ; hence the black colour of blood 

 which has been effused into the stomach, and the dark smokey hue of 

 acid urine containing blood. 



We have before spoken of the crystals to be obtained from the 

 blood. These crystals are very readily 'obtained by diluting blood 

 with water. A drop of blood may be placed upon a glass slide, and 

 after the addition of a drop of water, alcohol, or ether, the whole 

 should be lightly covered with thin glass. A hair, or a small piece of 

 thin paper or wood, may be placed between the glasses, in order that 

 a stratum of fluid of sufficient thickness may be retained. Whenever 

 it is possible, it is preferable to use defibrinated blood. Often the 

 corpuscles and a little serum may be removed from the clot by firm 

 pressure, and from this very perfect crystals may frequently be 

 obtained. The blood-corpuscles become ruptured by endosmosis, 

 their contents escape, and crystallise as the solution gradually becomes 

 concentrated. The time which elapses before crystallisation takes 

 place varies from an hour to several hours or days in different speci- 

 mens of blood. Crystals may also be obtained in a similar manner 

 from the coagulum of blood. 



The form of the crystal often varies slightly in the same specimen, 

 but the blood of different animals yields crystals of very different 

 forms. The prismatic form is that most commonly obtained from the 

 blood of man, the Carnirora, and fishes. Tetrahedral crystals appear 

 most common in some of the Rodentia, as the guinea-pig, while six- 

 sided tables are formed in the blood of the squirrel, mouse, and some 

 others. Teichmanu has succeeded in obtaining crystals from frog's 

 blood by the addition of a very large quantity of water at a very low 

 temperature. 



The crystals form more readily in daylight than in the dark, but 

 most rapidly when the slide is exposed in the light of the sun. 



Guinea-pig's blood crystallises in the course of half an hour, or even 

 sooner, if it be diluted with a little water or alcohol. Dog's blood 

 also crystallises in the course of a short time upon the addition of a 

 little alcohol. Human blood crystallises after the addition of water, 

 slowly if only just removed from the body, but more quickly if the 

 blood has been drawn a few hours. 



It is obvious from what has been said above that the microscope 

 is one of the most important instruments of research that has been 

 placed in the hands of man. Its practical value has not however been 

 yet fully recognised. It U employed by the medical man in the 

 diagnosis of diseases, but in medico-legal investigations in the detection 

 of adulterations in food, in ascertaining the value of fibrous materials 

 in the arts, and in many departments of industry, it has yet to 

 find its way. Dr. Beale gives the following instances of its utility as 

 a means of diagnosis : 



" 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 eren 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 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 pre- 

 sence of certain other deposit*, and a knowledge of the symptoms 

 usually associated with them, the physician is enabled to direct his 

 attention, as the casn 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. 



" Th recent discovery of a state of fatty degeneration affecting the 



arteries of the brain, 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 hyperacmh, as was 

 formerly supposed and acted upon. 



" The connection between fatty degeneration of the margin of the 

 cornea (arcus smilis), and similar changes taking place in the muscular 

 tissue of the heart (a subject which has 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 Ooodsir, and named by him Sarcina Yen- 

 Iriculi, 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. [ENTOPHYTA.J 



" 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 sub- 

 mitted to examination ; and they have been unable to pronounce as to 

 its malignant or non-malignant character. 



" On the other bond, 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." 



" 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, 

 . 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, 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. 



" Larvae 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 larva: of some large fly, but, as it was con- 

 fidently 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, 

 trachea: (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 Jintozoa, and that 

 they could not have been passed in the manner stated. They were 

 afterwards proved to be the larvae of a fly. 



Thn claws of Echinococci and portions of hydatid cysts have on 

 several occasions been discovered in the urine, sputa, &c., upon sub- 

 mitting portions of these fluids to microscopical examination, proving 

 beyond a doubt the existence of hydatids. [KNTOZO.V.] 



"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 por- 

 tions of almonds, gooseberry-skins, portions of potato, the testa of 

 the tamarind, husks of wheat, 4c. ; not many years ago the uredo of 

 wheat was mistaken for, and described as, a peculiar fungus, to 

 which it was supposed tho phenomena observed in coses 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 fteces, 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 iu cases of 

 rape, need only be adduced as examples of the importance of the 

 microscope in such investigations. 



" For Detecting Impurities in Food and Drugs the microscope has 

 afforded important aid, and there are several other purposes to which 

 it may be applied." 



