EXAMINATION OF ANIMAL FLUIDS. 689 



Microscope, the following table of the most common extraneous 

 matters constantly met with in urinary deposits. 



Fragments of human hair. Fragments of tea-leaves, or separated 



Cats' hair. spiral vessels and cellular tissue. 



Hair from blankets. Fibres of coniferous or other wood 



Portions of feathers. swept off the floor. 



Fibres of worsted of various colors. Particles of sand. 



Fibres of cotton of various colors. Oily matter in distinct globules, aris- 



Fibres of flax. ing from the use of an oiled cathe- 



Potato starch. ter, or from the accidental presence 



Rice starch. of milk or butter. 

 Wheat starch, bread crumbs. 



Great care, therefore, should be exercised in the collection and 

 preparation of urine for microscopic examination. It is a very 

 good practical rule to examine a portion of the urine an hour or 

 two after it is voided ; and another portion after standing a day, 

 or in some instances two days. Occasionally it will be necessary 

 to institute the examination immediately upon the passage of 

 the secretion, as in those instances where there is a strong and 

 rapid tendency to decomposition upon exposure to the atmo- 

 sphere, or where this change has already taken place in the 

 bladder. Urine containing lithic acid or oxalate of lime should 

 be allowed to stand for some time in order that it may be de- 

 posited. 



Perfectly healthy urine, after standing for about twelve hours, 

 exhibits a slight cloudy deposition, consisting of epithelial scales, 

 some crystals of the triple phosphate, and granular fragments of 

 the urate of ammonia. 



Urinary deposits are best obtained for examination by pouring 

 the fluid into a tall wine-glass, or wide-mouthed bottle, capable 

 of containing several ounces, and allowing it to stand for a few 

 hours. The clear supernatant liquid should then be poured 

 off, and the thick turbid under-stratum of urine, containing the 

 deposit, emptied into a small test-tube. The sediment will thus 

 be obtained in a small bulk, and can readily be examined by 

 being deposited upon a glass slide after the liquid portions have 

 been removed by means of a pipette. 



Large crystals of uric acid require an inch object-glass to be 

 seen distinctly; when very small a fourth of an inch glass is 

 necessary, as is the case also with the octohedral crystals of the 

 oxalate of lime, epithelium, casts of the uriniferous tubes, &c. 

 The eighth of an inch object-glass is best adapted for the exami- 

 nation of spermatozoa. 



In examining the deposits small portions should be brought 

 into the field of the microscope at a time, and in this careful 

 manner the different constituents, and their relation to each 

 other, may first be studied to considerable advantage with the 

 lower magnifying powers. Afterwards the nature and structure 

 of each object may be more minutely investigated by subjecting 

 it to the higher glasses. Sometimes it will be found advisable 



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