488 A MANUAL OF BACTERIOLOGY 



late been much on the increase, in Chicago the mortality 

 having reached as high as 20 per 10,000 inhabitants. 

 Acute croupous pneumonia sometimes occurs in epidemic 

 form and has decimated the native labourers in the Rand 

 mines. The serum of the Rand native has an opsonising 

 power for the pneumococcus lower than that of the serum 

 of the European. 1 



Besides acute croupous pneumonia, more than half 

 the cases of broncho-pneumonia, both primary and 

 secondary in the course of other diseases, are due to the 

 S. pneumonice, which is also associated with a number of 

 other important pathological conditions in man. It is a 

 pyogenic organism, producing abscesses when inoculated 

 into a relatively insusceptible animal such as a dog, and 

 is met with in abscesses, empyema, suppuration in the 

 antrum, and purulent arthritis. It is also found in about 

 half the cases of purulent meningitis, sometimes causing 

 a cerebro-spinal meningitis, in about a third of the cases 

 of otitis media and infective endocarditis, sometimes in 

 purulent pericarditis, and occasionally in peritonitis. The 

 pneumococcus is also frequent in chronic bronchial and 

 other catarrhs of the respiratory tract. An agglutination 

 reaction with patient's serum on the pneumococcus is only 

 very irregularly obtained, and normal serum rarely exerts 

 any bactericidal effect upon the organism. 



Toxins. Auld separated a proteose and an organic acid 

 from the blood and organs of infected animals, and from 

 cultivations of the S. pneumonice in alkali-albumin the 

 same products were apparently obtained, the alkaline 

 medium soon becoming permanently acid. The proteose 

 on subcutaneous or intravenous injection produced some 

 fever ; on intrathoracic injection fever and dyspnrea, and 

 post-mortem pleurisy and consolidation of the lung were 

 found. The organic acid produced slight rise of tempera- 



1 Wright, Lancet, 1914, vol. i, pp. 1 et seq. 



