TOXINS OF THE PNEUMOCOCCUS. 219 



fore we cannot say whether any similar pneumonic effects are 

 produced by it in partly susceptible animals. The organism 

 appears to be present alone in a small number of cases of 

 pneumonia, and the fact that it also appears to have been the 

 only organism present in certain septicsemic complications of 

 pneumonia, such as empyema and meningitis, render it possible 

 that it may be the causal agent in a few cases of the disease. 



In the septic pneumonias the different pyogenic organisms 

 already described are found, and sometimes in ordinary pneu- 

 monias, especially the catarrhal forms, other organisms, such as 

 the B. coli or its congeners, may be the causal agent. 



The Toxins of Fraenkel's Pneumococcus. — Pneumonia in its 

 commonest types is a disease which presents in many respects 

 the characters of an acute poisoning. In very few cases does 

 d^ath take place from the functions of the lungs being interfered 

 with to such an extent as to cause asphyxia. It is from car- 

 diac failure, from grave interference with the heat-regulating 

 mechanism, and from a general nervous depression that death 

 usually results. These considerations, taken in connection with 

 the fact that in man the pneumococci are usually confined to 

 the lung, suggest that they may produce their general effects by 

 means of toxins. The subject has been investigated by Em- 

 merich and Fowitsky and by G. and F. Klemperer. The latter 

 isolated from recent bouillon cultures, by the methods of Brie- 

 ger and Fraenkel (p. 172), bodies having the reactions of the 

 toxalbumins obtained in the case of other bacteria. When 

 injected, these toxalbumins (which they called " pneumotoxin ") 

 produced symptoms in rabbits, and when they were derived not 

 from bouillon cultures but from the blood of animals dead of the 

 disease, they could produce fatal effects. This work was done 

 before media had been devised on which the pneumococcus can 

 live for a number of weeks, and therefore only the toxins 

 resulting from a few days' growth were used. Of the nature of 

 the poisons which were obtained we know nothing. Carnot 

 describes a toxin which, when introduced into an animal's lung, 

 gave rise to pneumonic conditions, and also secondarily produced 

 changes in the heart and symptoms of cardiac affection similar 

 to those occurring during the disease in the human subject. 



Immunisation against the Pneumococcus. — Animals can be 

 immunised against the pneumococcus either by inoculation with 



