498 INFECTION AND IMMUNITY. 



protective powers, it is of less value when used for 

 curative purposes. It produces no effect after the 

 blood stream has been invaded by the bacilli. Its 

 greatest value is for the protection of herds when 

 anthrax has declared itself. In man it has been 

 used chiefly in the treatment of malignant pustule 

 in which the prognosis, even without specific treat- 

 ment, is not unfavorable. The best known serums 

 are those of Sclavo, prepared from the goat and ass, 

 of Mendez and Deutsch. The properties on which 

 the value of the serums depends are unknown. So- 

 bernheim is very positive in stating that the bac- 

 tericidal power of an animal's serum is not in- 

 creased by immunization or infection, and the ex- 

 istence of an antitoxin is not recognized. As in 

 some other instances immunization may cause an 

 increase in opsonins which would render the serum 

 effective by its power to cause increased phagocy- 

 tosis. 



Mixed im- The method of Sobernheim, that of mixed active 

 and P assive immunization, seems to be successful 

 ation. as a prophylactic measure. The vaccine consists 

 of a mixture of antiserum and bacilli. Immune 

 and even normal serums at times may agglutinate 

 the anthrax bacillus, but the reaction is inconstant, 

 and the ability of an immune serum to cause ag- 

 glutination is no index of its protective power. Ag- 

 glutination is somewhat difficult of determination 

 because of the tendency of the bacillus to grow in 

 the form of chains. 



II. MALTA FEVER. 



Malta, Mediterranean or undulant fever, discovered 

 in the Island of Malta, also occurs among British 

 troops at Gibraltar, and cases have been discovered 



