BACTERIAL VACCINES 173 



immunity. In these cases it is necessary to first 

 prepare the way by the use of dead or of attenuated 

 cultures. 



Treatment with Vaccines. The treatment of 

 infections by means of active immunization has 

 been greatly stimulated by the work of Wright, 

 who has published favorable results in a large 

 number of infections. Already several hundred 

 thousand persons have been actively immunized 

 against cholera, and large bodies of troops have 

 been immunized against typhoid fever. Until 

 recently the method found application particu- 

 larly in the prophylactic immunization of persons 

 liable to be exposed to infection. At the present 

 time, however, owing largely to the efforts of 

 Wright, the method has come to be used for cura- 

 tive purposes, i.e., for infections already in progress. 

 This author has clearly formulated the conditions 

 in which he thinks this form of treatment is indi- 

 cated, and he has also devised methods for the 

 more exact determination of doses than were 

 formerly in use. 



In the employment of bacterial vaccines, one 

 must constantly keep in mind the nature of the 

 bacterium with which one is working, and the kind 

 of immunity one wishes to bring about. Every- 

 thing depends on the way in which the vaccine is 

 prepared. With bacteria making considerable 

 quantities of a toxin, it will be necessary, if we 



