562 IMMUNITY 



3. The separating of the well animals from the sick ones 

 and from the infected stables, pens; yards, or fields is not 

 usually an expensive procedure. The stables and yards can 

 be disinfected and the infected fields can be utilized for other 

 purposes until the virus has been destroyed by its own limited 

 life cycle. In this connection, it is well to call attention to 

 efforts that are being put forth to eliminate the cattle tick from 

 the Southern States and thus prevent Texas fever. 



REFERENCES. 



1. Ernst. Modem theories of Bacterial Immunity. Boston, 1903. 



2. Metchnikoff. Immunity in Infective Diseases. Cambridge. 

 1905- 



3. NuTTAi,!,. Blood Immunity and Blood Relationship. Cam- 

 bridge, 1904. 



4. Sobernheim. Deutsche Med. Wochenschrift. 1904, No. 26, S. 

 27. 



5. STERNBERG. Immunity, Protective Inoculations in Infectious 

 Diseases and Serum- Therapy. New York, 1895. 



6. WaSSKRMann. Immune Sera, Hsemolysins, Cytotoxins, and 

 Precipitins. Nev? York, 1904. 



7. Vaughn and Novy. Cellular toxins or the Chemical Factors 

 in the Causation of Disease. 



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