32 INFECTION AND IMMUNITY. 



curve), streptococcus infection of tubercular cavi- 

 ties, and the development of acute tuberculosis 

 during measles these are important examples of 

 secondary infections. 



We should naturally expect that the presence of 

 a severe secondary infection might embarrass at- 

 tempts at serum therapy and vaccinal therapy 

 Experience regarding the former is limited prac- 

 tically to diphtheria, and there is no lack of evi- 

 dence to show that the disease when complicated 

 by severe streptococcus infection sometimes can- 

 not be controlled by antitoxin treatment; and in 

 vaccinal therapy (injection of micro-organisms or 

 their products) it is emphasized from all sides that 

 in the presence of mixed infection it is advisable 

 to inject preparations of the secondary as well as 

 the primary organisms concerned. 



