144 CLINICAL BACTERIOLOGY AND HiEMATOLOGY 



that occasionally very few of the organisms appear to grow into 

 colonies, as far as can be judged by a comparison between the 

 numbers of cocci present in the films and of colonies on the tubes. 

 This indicates that the majority of cocci are dead, and this makes 

 the prognosis better. The prognosis is also good in cases in which 

 very few cocci are present, and in those in which the cocci that 

 are present are largely contained in the leucocytes ; in this case 

 they may lose their power of retaining Gram's stain. 



The streptococcus is also readily demonstrated by a simple micro- 

 scopical examination ; it grows readily on agar, forming small 

 round colonies, which do not tend to coalesce and are more opaque 

 in the centre than at the periphery. 



The pus is not generally very thick, and has a yellow colour. 

 It separates into two layers, the upper transparent layer being 

 much more abundant than is the case with pneumococcic pus. 



This form of empyema is rare in children, but is perhaps, on 

 the whole, the commonest one in adults. The prognosis is much 

 worse than in the pneumococcic cases, and thorough drainage and 

 resection of the ribs is essential. 



Staphylococcic empyemata, according to Netter, are very rare ; 

 the single case in which he found the staphylococcus alone was 

 secondary to ulcerative endocarditis. He also states that when 

 this organism is found in the pus tubercle bacilli are often present as 

 well. The prognosis of these cases, therefore, appears to be bad. 



The tubercle bacillus is responsible for a comparatively small 

 number of cases, and the results of operative interference are 

 not gratifying. The prognosis is worse than in any other form of 

 the disease. 



The pus is usually white in colour, and thin and watery. It 

 may contain small masses of white caseous material. The leuco- 

 cytes which it contains are nearly all lymphocytes, unless a 

 secondary infection with pus organisms has taken place. 



The diagnosis may be made from a careful microscopical 

 examination, but to this end it must be careful, as the bacilli are 

 often present in but scanty numbers. 



If no organisms are found after a thorough microscopical 

 examination, the inference is that the case is tuberculous. If 

 a cultural examination is also negative the inference becomes 

 almost a certainty. 



The empyemata arising from rupture of the cesophagus, stomach 

 intestine, etc., into the pleura, in those due to an external wound 



