142 THE ACUTE SELF-LIMITED INFECTIONS 



The blood acquires some resistance to dysentery 

 bacilli during an attack, comparable closely to the 

 changes in cholera , that is bacterioly tic substances and 

 agglutinins are to be found. Advantage of this is taken 

 in immunizing the lower animals with toxins obtained 

 in laboratory cultures. In order to discover if dysen- 

 tery bacilli be present, laboratory cultivation of the 

 stools is undertaken, using as material the bloody 

 parts, mucus or shreds of membrane, in any and all 



, 



* 



-. f 



FIG. 39. Dysentery bacilli. X 1000 diameters. (Park.) 



of which the germs abound. The development in the 

 laboratory is comparatively simple, but to identify 

 the species or variety is anything but easy. The 

 agglutinins in the patient's blood may be tested 

 against pure laboratory cultures of known varieties, 

 and thus a bacteriological diagnosis as to the type 

 .may be made. Thus, for diagnosticating dysentery 

 we have only the feces culture and agglutination test. 

 Since the bacilli are not in the blood, cultures of this 

 are not made. 



