200 URINARY SEDIMENTS. 



red blood-corpuscles. They appear granular, but when 

 brought in contact with acetic acid the granulation dis- 

 appears and the nuclei, of which there are two or three, 

 become visible. (Plate III, 13.) When the urine becomes 

 alkaline, either by fermentation or by the addition of a 

 fixed alkali, the corpuscles disappear and the mass be- 

 comes very sticky and gelatinous, so that it can be drawn 

 out by a glass rod into long threads. The turbidity of 

 urine which contains pus resembles that from urates or 

 from the earthy phosphates. It does not disappear, how- 

 ever, like the former, by warming, nor, like the latter, upon 

 the addition of acids. 



The source of the pus in the urine may be anywhere 

 in the urinary tract. When it is from the kidney the urine 

 is apt to be acid in reaction, and round-celled epithelium 

 or casts may be present. When it is from the bladder the 

 urine is usually alkaline. It may be due to simple inflam- 

 mation or to some deep-seated affection of the tissues. 



416. Examine microscopically urine containing pus. 

 Remove the excess of liquid around the cover-glass by 

 means of a piece of filter-paper. Put a drop of acetic acid 

 on the slide and let it run under the cover-glass. Notice 

 the change in the appearance of the corpuscles. 



417. Show that the turbidity does not disappear 

 upon warming or upon acidifying. 



418. Make Donne's test for pus by allowing it to 

 settle, then, after decanting off the urine, making it alka- 

 line with sodium hydrate. The mass becomes extremely 

 viscid, as is shown by stirring or pouring. 



419. Show that the pus responds to the albumin re- 

 actions. 



Mucus as a sediment is in the form of a slimy, viscid 

 liquid, sometimes showing the mucous corpuscles. Its sig- 



