220 ACUTE PNEUMONIA. 



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

 the disease. 



The Toxines of Fraenkel's Pneumococcus. Pneumonia 

 is a disease which presents in many respects the characters 

 of an acute poisoning. In very few cases does death take 

 place from the functions of the lungs being interfered with 

 to such an extent as to cause asphyxia. It is from cardiac 

 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 toxines. The subject has 

 been investigated by Emmerich and Fowitsky and by G. 

 and F. Klemperer. The latter isolated from recent bouillon 

 cultures, by the methods of Brieger and Fraenkel (p. 154) 

 bodies having the reactions of the toxalbumins obtained in 

 the case of other bacteria. When injected, these tox- 

 albumins (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. We have seen 

 that ordinarily the pneumococci rapidly lose their virulence 

 in artificial media, and therefore instead of letting bouillon 

 cultures go on for a month, as in the case of diphtheria, 

 the Klemperers had to be content with two days' growth to 

 obtain the maximum effect. We can say little of the true 

 nature of these toxines. Their activity is interfered with 

 by an hour's exposure at 60 C., but, as in the case of 

 other toxines, whether they are really proteids, or non- 

 proteid bodies carried down with the latter in the methods 

 of precipitation used, we do not know. 



Immunisation against the Pneumococcus. Animals can 

 be immunised against the pneumococcus either by inocula- 

 tion with attenuated cultures or by the injection of toxic 

 bodies derived from cultures. The former can be effected 

 by cultures which have become attenuated by growth on 

 artificial media, or by the naturally attenuated cocci which 



