TREATMENT. 513 



serum. According to Collins, pneumococci fall 

 into different groups, depending on their agglu- 

 tinable properties; the same author determined 

 the presence of group agglutinins in an immune 

 serum. Neufeld states that avirulent strains were 

 not agglutinated by the serum of pneumonic pa- 

 tients. 



Beginning with Fraenkel (1886), many have vaccine 



, .,.,., v . '> ? , Treatment. 



shown the possibility of increasing the resistance 

 of susceptible animals to the pneumococcus by in- 

 jecting first dead or avirulent and then virulent 

 cultures; in this way the subjects can be made to 

 withstand many multiples of the minimum fatal 

 doses. Eosenow has been able to separate, by a 

 process of autolysis, the more toxic part of the 

 pneumococcus, and the bodies of the organisms. 

 By the use of the non-toxic part as antigen, a 

 more rapid development of antibodies can be 

 obetained, experimentally, than can be accom- 

 plished with whole pneumococci; Eosenow has 

 made this fact the basis of treatment of pneu- 

 monia by means of injection of the autolyzed bod- 

 ies of pneumococci and has obtained encouraging 

 results. It is hoped that this procedure will be a 

 valuable aid in hastening the crisis. 



OTHER INFECTIONS BY THE PNEUMOCOCCUS. 



Complicating infections by the pneumococcus 

 during the course of pneumonia were mentioned 

 above. They may occur by way of the lymph 

 channels, as in pleuritis, pericarditis and peritoni- 

 tis (through the diaphragm), by continuous exten- 

 sion, as in infection of the bronchi, nose and, per- 

 haps, the middle ear, or as metastatic infections 

 following the invasion of the blood stream by the 



