364 INFECTION AND IMMUNITY. 



products (the bacterial proteins, as Koch's old 

 tuberclin and mallein; the soluble toxins; 

 products of bacterial autolysis). When toxins 

 are injected antitoxins are formed. The 

 autolytic products of some organisms, e. g., 

 typhoid and dysentery, cause the formation of bac- 

 tericidal amboceptors and agglutinins, but not 

 antitoxins. 



B. Passive immunization: the prophylactic in- 

 jection of antibacterial and antitoxic serums. 



C. Mixed active and passive immunization : the 

 simultaneous injection of an immune serum with 

 the corresponding organism, which may be killed 

 or living. The serum causes immediate, though 

 temporary, resistance, and, in the meantime, an 

 active, more permanent immunity develops as a 

 consequence of the injection of the organ.'sms. 

 This method has been practiced with swine plague, 

 swine erysipelas, rinderpest, and experimentally 

 in typhoid, cholera and plague. 



II. CURATIVE INJECTIONS. 



A. Active immunization. 



1. Injection of killed micro-organisms in small 

 doses with the intention of hastening antibody for- 

 mation, as suggested by Fraenkel in the treatment 

 of typhoid fever ; value not yet demonstrated. 



B. Passive immunization. 



1. With antitoxic serums: diphtheria, tetanus, 

 snake bites, plague, tuberculosis (?), typhoid (?), 

 streptococcus infections (?), etc. 



2. With antibacterial serums: typhoid, cholera, 

 plague, dysentery, streptococcus (?), staphylococ- 

 cus (?) and pneumococcus (?) infections. 



