106 BACTERIOLOGY 



in from twelve to twenty-four hours, when the patient 

 feels as well as ever. 



The use of the vaccine is becoming a routine measure 

 in the armies of the world, where it is proving most suc- 

 cessful, it having been found that less than half as many 

 vaccinated men have the disease as those not vaccinated, 

 while the mortality among those vaccinated who do not 

 contract the disease is less than one-fourth that among 

 the unvaccinated. There is no question but that it will 

 soon become a common procedure among nurses, doc- 

 tors, travellers, and others whose duties lay them liable 

 to infection. 



Tuberculin. While tuberculin differs in its constitu- 

 ents from the other bacterial vaccines, the principle 

 upon which it acts is practically the same, that is, the 

 increase of the opsonic index and of the resistance of 

 the individual to the tubercle bacillus and its toxins. 



The discovery of tuberculin by Koch in 1890 antedates 

 the development of the principle of opsonic therapy by 

 many years. Unguided by subsequent knowledge of 

 this form of treatment, the early advocates of tuberculin 

 in treatment met with disaster in its use, and its employ- 

 ment became restricted to its use as a diagnostic measure. 

 The knowledge gained in the use of bacterial vaccines 

 and opsonic index has enabled us to use tuberculin with 

 advantage in the treatment of tuberculosis. 



The method of employing tuberculin as a remedy con- 

 sists of the administration in the beginning of very 



