254 MANUAL OF BACTERIOLOGY. 



The diplococci can readily be demonstrated in sections of 

 pneumonic lung, which are best stained by carmine and 

 gentian-violet, by the Gram method. Although the exudate 

 at first contains many red blood-cells and the solid lung 

 appears red, subsequently it becomes decolorized and pre- 

 sents a gray color. Many leucocytes will now be found to 

 have migrated into the air-vesicles, and the lung will have 

 become relatively anemic, instead of hyperemic. Finally, 

 the fibrinous exudate and the cells entangled in it become 

 softened and liquefied. Some of this liquefied exudate is 

 absorbed into the lymphatics in the walls of the air-vesicles ; 

 part of it is expectorated. 



The micrococcus lanceolatus can be detected in large 

 numbers, sometimes almost unmixed with other bacteria, 

 in the rusty sputum of lobar pneumonia, often showing the 

 peculiar unstained capsule. On account of its liability to 

 be mixed with other forms of bacteria, its presence in the 

 sputum of cases suspected of being pneumonia is not of 

 very great value in differential diagnosis, especially con- 

 sidering that it is so commonly present in the normal mouth. 

 In a suspicious case its appearance in sputum in nearly pure 

 culture may be significant. 



Cultures from the blood of cases of pneumonia, where a 

 large amount of blood is taken, have shown the presence 

 of the pneumococcus in a considerable proportion of the 

 cases, especially when severe or fatal. 



The micrococcus lanceolatus is often also the cause of 

 broncho-pneumonia and of meningitis. It produces inflam- 

 mations in other situations as well, the most important be- 

 ing pleuritis, pericarditis, endocarditis and arthritis. The 

 micrococcus lanceolatus may produce pseudomembranous 

 inflammation 1 and also ordinary suppuration, although not 

 very commonly. 



1 Gary and Lyon, American Journal Medical Sciences, Vol. 122, 1901. 



