126 CLINICAL BACTERIOLOGY AND HiEMATOLOGY 



The microscopical examination is made in the manner described 

 for pus, a simple stain and also Gram's stain, with dilute carbol 

 fuchsin as a counterstain, being used. The presence of strepto- 

 cocci, staphylococci, and pneumococci will be revealed ; bacilli 

 may be present, and in this case it should not be forgotten that 

 the tubercle bacillus stains by Gram's method. If no organisms are 

 found in these films, or if there are organisms which resemble the 

 tubercle bacillus in general appearance, another specimen should 

 be submitted to prolonged staining in hot carbol fuchsin and de- 

 colorization in dilute sulphuric acid, and thoroughly searched for 

 the tubercle bacillus. If the result is negative, several other films 

 should be searched. 



The cultures are to be examined after twenty-four hours' incu- 

 bation. The pneumococcus will produce tiny colourless colonies 

 on the surface of the agar ; the streptococcus forms similar small 

 colourless colonies, but these are distinctly more opaque in the 

 centre ; staphylococci form opaque white or yellowish colonies 

 which, after longer incubation, spread out, coalesce, and cover the 

 surface of the agar with an even film like a streak of paint ; and 

 the tubercle bacillus does not develop. Films should be made 

 from the cultures, stained and examined. The cultural examina- 

 tion 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 described. 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, gonococcus, and tubercle bacillus, 

 are the most important. The coccus which has been described 

 by several observers as the cause of acute rheumatism cannot be 

 considered as of diagnostic importance at present ; the same remark 



