272 



PRACTICAL PHYSIOLOGY 



below it, is obtained. 1 Now add the reagent up to the mark E. 

 Close the tube with a tightly-fitting cork and invert several times, so 

 as to mix the fluids thoroughly. Allow to stand in an upright 

 position for twenty-four hours, and then read off the graduation 

 corresponding to the top of the precipitate. This gives the number 

 of gr.ammes of dried albumin per litre of urine used. If the urine has 

 been diluted the necessary calculation must be made in order to 

 obtain the percentage in the original urine. 



For more accurate estimation of albumin, Scherer's method is employed. 

 EXPERIMENT. Place 50-100 c.c. urine (according to amount of albumin 



in it) in a large-sized evaporating dish, and, while stirring, bring to the boil. 



Carefully add a few drops of dilute acetic acid, and allow the coagulum to 

 settle down. If the supernatant fluid is opalescent, add a 

 little more acetic acid, and bring again to the boil. (It is 

 very important to use as little acetic acid as possible, so that 

 acid abumin may not be formed.) The coagulum must then 

 be collected on a small ash-free filter paper which has been 

 dried between watch-glasses at 120 C. After being collected 

 on the filter, wash the coagulum with boiling water, followed 

 by alcohol and ether, and dry it at 120 C. until the weight is 

 constant. Since the coagulum contains considerable ash, the 

 filter and coagulum must now be transferred to a weighed 

 crucible, incinerated, and the weight of ash deducted from 



B 



5 



the weight of dried coagulum. 



Mucus, Pus, and Casts in Urine. When the kidneys 

 or urinary passages are diseased, besides protein 

 there may be a considerable deposit of mucus in the 

 urine. This body has the general properties and solu- 

 bilities of mucin (see p. 201), but may consist largely 

 of nucleo-protein. Casts also occur in the deposit 

 from the urine. When these come from the urinary 

 passages, they consist of groups of flattened epithe- 

 lial cells. When they come from the kidney tubules, 

 they are tubular and consist of polyhedral cells, 

 showing various stages of degeneration. When the 

 kidneys or urinary passages are infected by micro- 

 organisms, pus cells occur in the urine and form 

 Strong potash dissolves the pus, forming a viscid 

 solution. Pus also gives a guaiac test as for blood, but much 

 more slowly and not after boiling, which destroys the oxidases to 

 which the test is due. The only certain test for pus, however, is to 

 examine the urine or deposit with the microscope. The pus cells 

 appear as colourless, spherical, highly refractive granular bodies, 

 about 9 11 in diameter, the nuclei of which can be stained by adding 

 dilute methylene blue. The urine is usually acid when the pus 

 comes from the kidney, and alkaline when the pus comes from the 

 bladder, due to the decomposition of urea and ammonium carbonate. 

 Haemoglobin in Urine. This may be due to bleeding from the 

 kidneys or urinary passages, when it is called hcematuria, or to 



1 These corrections should be made before the urine is measured into the 

 Esbach's tube. 



FIG. 193. 



Esbach's 



albumin o- 



meter. 



a deposit. 



