IMMUNITY 



71 



of a broth culture of typhoid bacilli, and this mixture 

 of diluted blood and typhoid culture then examined by 



Fig. 23. Typhoid bacilli unagglutinated (Jordan). 



means of the hanging-drop method under the micro- 

 scope. If complete agglutination takes place within 



Fig. 24. Typhoid bacilli partially agglutinated (Jordan). 



twenty to thirty minutes, one speaks of having obtained 

 a positive Widal reaction. This means that the patient 



