

THE PNEUMOCOCCUS AND PNEUMONIA 441 



met with under artificial cultural conditions. This may be chiefly 

 due to the cultural conditions or may be a prominent characteristic 

 of certain strains. Apparently the capsules of organisms making 

 up the chains are continuous ; wavy indentations are usually present, 

 however, in the capsule of chains, and at times distinct divisions 

 are observed. 



The chief variations from the typical morphology consist either in 

 the assumption of a more distinctly spherical coccus type, or in an 

 elongation approximating the bacillary form. Under certain condi- 

 tions of artificial cultivation a distinct flattening of the organisms, 

 particularly of those making up chains, may be seen, and even the 

 impression of a longitudinal line of division, characteristic of many 

 streptococcus cultures, is not infrequently gained. 



The capsules under certain conditions, especially in artificial 

 media, may be absent or not demonstrable, and in certain strains 

 capsules apparently may not be present under any conditions. 

 Practically any of the described variations may dominate one and 

 the same culture under different or even apparently the same con- 

 ditions of cultivation, and all grades may occur in capsule develop- 

 ment, from its typical formation through all variations, to its total 

 and apparently permanent absence. 



The presence or absence of capsules depends, to a large extent, 

 upon the previous environment of the pneumococci under observa- 

 tion. The most favorable conditions for the development or preser- 

 vation of the pneumococcus capsule are found in the body fluids of 

 man and animals suffering from pneumococcus infection. For 

 instance, capsules may be demonstrated with ease by the usual 

 capsule-staining methods in the blood, serum, and inflammatory 

 exudate of the infected rabbit and white mouse. Capsules may be 

 equally well marked in the fresh sputum of pneumonia patients, 

 especially in the early stages of the disease and in the exudate accom- 

 panying such pneumococcus infections as meningitis, otitis media, 

 and empyema. In sputum and the exudates of various localized 

 infections, the organisms are, however, frequently degenerated or 

 under chemical conditions unfavorable for capsule staining, and 

 satisfactory results are not then easily obtained. The same is often 

 true of the scrapings from lungs of patients dead of pneumonia, 

 even in the stage of red hepatization. 



In artificial cultivation, if the nutrient medium is not milk or 

 does not contain serum, capsules cannot usually be demonstrated by 



