PATHOGENIC BACTERIA. 129 



Agar. The gases develop more strongly in this medium, and 

 the odor is more prominent. 



Guinea-Pig Bouillon. In an atmosphere of hydrogen cloud- 

 ing of the entire culture medium without any flocculent pre- 

 cipitate until third day. 



Staining. Arc stained with the ordinary dyes, but Gram's 

 method is not applicable. 



Pathogenesis. When experiment animals, mice or guinea- 

 pigs, are injected with a pure culture under the skin they die in 

 8 to 15 hours, and the following picture presents itself at the 

 autopsy : In guinea-pigs from the point of infection, spreading 

 over a large area, an oedema of the subcutaneous tissues and 

 muscles, which are covered and saturated with a clear red 

 serous exudate free from smell. This contains great quantities 

 of bacilli. 



The spleen is enlarged, especially in mice. The bacilli are 

 not found in the viscera, but are present in great numbers on 

 the surface, i. 6., in the serous coverings of the different organs ; 

 though when any length of time has elapsed between the death 

 of the animal and the examination, they can be found in the 

 inner portions of the organs, for they grow well upon the dead 

 bod}'. In man they have been found in rapidly spreading gan- 

 grene. They are present in the soil, in putrefactions of various 

 kinds, and in dirty water. 



Immunity. IK produced by injection of the sterilized cul- 

 tures, and also the filtered bloody serum of animals dead with 

 the disease. 



Spirillum of Relapsing Fever. (Obermaier.) 



Syn. Spirocheete Obermaieri. 



Origin. Found in the blood of recurrent fever patients, 

 described in 1873. 



Form. Long, wavy threads (16 to 40 ^ long), a true spiril- 

 lum ; flagella are present. 



Properties. Very motile. Has not been cultivated. 



Staining. Ordinary aniline stains. Bismark brown best for 

 tissue sections. 



Pathogenesis. Found in the organs and blood of recurrent 

 fever. Man and monkeys inoculated with blood from one suf- 



