148 



PRACTICAL PHYSIOLOGY. 



[XXIV. 



(a.) Donne's Test. Filter off the fluid, and add to the deposit a small 

 piece of caustic potash, or a few drops of strong solution of caustic potash : 

 the deposit becomes ropy and gelatinous, and cannot be dropped from one 

 vessel into another due to the formation of alkali-albumin ; the deposit is 

 pus. The same reagent with mucus causes the deposit to become more fluid 

 and limpid, to clear up, and look like unboiled white of egg. 



FIG. 75. Hand Centrifuge made by Muencke, Luisen Strasse, 58, Berlin, N.W. 

 Cost, ^ 3 , io/. 



(b.} With the microscope numerous pus-corpuscles are seen, which, when 

 acted on by acetic acid, show a bi- or tri-partite nucleus. This test is not 

 absolutely conclusive. 



(c.) Urine containing pus gives the reactions for albumin, while, if mucus 

 alone be present, it gives only those for mucin. 



