BACILLUS ANTHRACIS AND ANTHRAX 575 



extremely high degree in order to obtain any appreciable protective 

 power in the serum. This is accomplished by preliminary treatment 

 with Pasteur's or other attenuated vaccines, followed by gradually 

 increasing doses of fully virulent cultures. Treatment continued at 

 intervals of two weeks, for two or three months, usually produces an 

 effective serum. Horses and cattle may also be used for the process, but 

 they are believed by Sobernheim to give less active sera than sheep. 

 Bleeding is done about three weeks after the last injection. The sera 

 are stable and easily preserved. 



Injections of 20 to 25 c.c. of such a serum have been found to protect 

 animals effectually from anthrax and to confer an immunity lasting 

 often as long as two months. Animals already infected are said to be 

 saved by treatment with 25 to 100 c.c. of the serum. 



Neither specific bactericidal nor bacteriolytic properties have, so 

 far, been demonstrated in these immune sera. In fact, these properties 

 are distinctly more pronounced against Bacillus anthracis in the normal 

 sera of rats and dogs. Agglutinins have not been satisfactorily demon- 

 strated in sera, partly because of the great technical difficulties en- 

 countered in the active chain-formation of the bacillus in fluid media. 

 An increase of opsonic power of such serum over normal serum has 

 not been satisfactorily demonstrated. 



Bacteria Closely Resembling Bacillus anthracis.^In most laboratory 

 collections there are strains of true anthrax bacilli so attenuated that 

 they are practically non-pathogenic. These do not differ from the 

 virulent strains in any morphological or cultural characteristics. 

 Besides such strains there are numerous non-virulent bacteria culturally 

 not identical with Bacillus anthracis, but resembling it very closely. 



B. ANTHHAcoiDBS {Hueppe and Wood ') . — A Gram-positive bacillus, 

 morphologically different from B. anthracis in that the ends are more 

 rounded. Culturally, somewhat more rapid in growth and more rapid 

 in gelatin fluidification. Non-pathogenic. Otherwise indistinguishable 

 from B. anthracis. 



B. RADicosus (Wurzel Bacillus) . — Cultivated from water — city water 

 supplies. Morphologically somewhat larger than Bacillus anthracis, and 

 the individual bacilli more irregular in size. Very rapid fluidification of 

 gelatin and growth most active at room temperature. Non-pathogenic. 



B. suBTiLis {Hay Bacillus). — Although not very closely related to 

 the anthrax group, this bacillus is somewhat similar and conveniently 



" Hueppe und Wood, Berl. klin. Woch., xvi, 1889. 



