THE DYSENTERY GROUP 



219 



tilizer and the frequent infection of the small streams and wells, 

 is over 20 per cent. 



Immunity. Bacteriolysins and agglutinins are abundantly 

 produced in the immune serum of both human beings and animals. 

 Since there are so many strains of dysentery bacilli it is customary 



FERMENTATION REACTIONS OF THE PRINCIPAL MEMBERS 

 OF THE COLON-TYPHOID GROUP 



m = motility 

 4- + = acid and gas production 



+ =acid production only 

 C = coagulation 



to inject animals with an individual strain and so produce a " mon- 

 ovalent " serum or to inject them with mixed strains and so give 

 rise to a " polyvalent " serum, the former for therapeutic use when 

 the type of organism causing the disease has been determined and 

 the latter when the strain is unknown. In mild cases doses from 

 10 c.c. to 30 c.c. are given twice daily according to the weight of 

 the patient ; in severe cases as much as 100 c.c. may be given. 



