124 BACTERIOLOGICAL DIAGNOSIS. 



staphylococci form an even film like a streak of paint ; 

 and the tubercle bacillus does not develop. Films 

 should be made from the cultures, stained and exam- 

 ined. The cultural examination is of great value, but 

 much can be made out by the examination of stained 

 films made directly from the pus. 



FLUIDS FROM JOINTS. 



The technique of the process of withdrawing these 

 fluids is exactly the same as in the case of pleurisy ; the 

 needle will naturally be inserted at a point where there 

 is definite evidence of the presence of fluid, and where 

 it lies near the surface. 



The bacteriological examination is conducted on 

 exactly similar lines. A few drops of the fluid should 

 be allowed to flow on to the surface of a sloped tube 

 of agar, and the culture obtained after twenty-four 

 hours' incubation examined in the manner already de- 

 scribed. Films should also be made directly from the 

 fluid and some stained by Gram's method and others 

 by a simple stain such as carbol-thionin. 



A great number of organisms may be present ; the 

 streptococci, staphylococci, the pneumococcus, gono- 

 coccus, and tubercle bacillus are the most important. 

 The coccus which has been described by several ob- 

 servers as the cause of acute rheumatism cannot be 

 considered as of diagnostic importance at present ; the 

 same remark applies to the bacillus which is probably 

 the cause of rheumatoid arthritis. 



Streptococci are readily distinguished on microscopi- 

 cal examination and may be present even if the fluid 

 is perfectly clear. When they are present in a joint 



