498 Pneumonia 



Metabolic Products. Hiss * found that the pneumococcus 

 produces acid with ease from monosaccharids, disaccharids, 

 and such complex saccharids as dextrin, glycogen, starch, 

 and inulin. The fermentation of inulin is most important as 

 a means of differentiating pneumococci from streptococci, 

 which cannot ferment it. 



Toxic Products. Nothing definite is known about the 

 metabolic toxic products of the pneumococcus. That the 

 symptoms of pneumonia are not entirely dependent upon 

 the disturbance of respiration is clearly shown by the fact 

 that the patients suffer from high fever and have marked 

 leukocytosis with enlargement of the spleen. The cases in 

 which the cocci invade the blood are usually more serious 

 than those in which their operations are restricted to the 

 lung. 



The toxin must be purely or almost purely intracellular, 

 however, as filtered cultures are scarcely at all toxic. 



Auldf found that if a thin layer of prepared chalk were 

 placed upon the bottom of the culture-glass, it neutralized 

 the lactic acid produced by the pneumococcus, and enabled 

 it to grow better and produce much stronger toxin. Mal- 

 fadyenj found that by freezing cultures of the pneumococcus 

 with liquid air and then destroying them by trituration in the 

 frozen state and then extracting the fragments with i : 1000 

 caustic potash solution, a toxin whose activity corresponded 

 fairly well with the virulence of the culture could be secured. 

 This toxin killed rabbits and guinea-pigs in doses varying 

 from 0.5 to i c.c. 



Pathogenesis. If a small quantity of a pure culture 

 of the virulent organism be introduced into a mouse, rabbit, 

 or guinea-pig, the animal dies in one or two days. Exactly 

 the same result can be obtained by the introduction of a piece 

 of the lung-tissue from croupous pneumonia, by the intro- 

 duction of some of the rusty sputum, and frequently by the 

 introduction of human saliva. Postmortem examination 

 of infected animals shows an inflammatory change at the 

 point of subcutaneous inoculation, with a fibrinous exudate 

 similar to that succeeding subcutaneous inoculation with 

 the diphtheria bacillus. At times, and especially in dogs, 

 a little pus may be found. The spleen is enlarged, firm, and 



* "Jour. Exp. Med.," vn, No. 5, Aug. 25, 1905. 

 f "Brit. Med. Jour.," Jan. 20, 1900. 

 J Ibid., 1906, ii. 



