PATHOGENIC BACTERIA. 165 



Tuberculin is prepared by concentrating with heat the glycerine- 

 bouillon, containing an old growth of tuberculosis, and filtering 

 through unglazed porcelain. It is used for the detection of tuber- 

 culosis in animals. The suspected animal is injected with the 

 tuberculin,, and a sudden rise of temperature, or suppuration of 

 tubercular formations, may be considered as proof that the ani- 

 mal is infected with the disease. 



II. Bacillus Typhosus. 



The bacillus of typhoid fever is a motile parasite found in the 

 urine and fecal discharges of typhoid patients. The rods have 

 rounded ends, and sometimes grow out into long filaments. It pro- 

 duces a whitish growth on agar, growing best at 35 degrees Centi- 

 grade. Spore-formation has not been observed. It may be stained 

 with aqueous solutions of fuchsin, methylene blue and gentian- 

 violet. 



The detection of typhoid in a patient may be made by adding to 

 some serum obtained from his blood a 'quantity of pure culture. It 

 the patient has the disease, the motile germs will soon cease their 

 movements. Flagella may be demonstrated by method No. 13. 



III. Bacillus Pyocyanus. 



This species is an actively-motile aerobic parasite, presenting 

 very short, slender staves. It is found in green pus, and produces a 

 greenish- white growth on agar-agar at the room temperature. It 

 may be stained with aqueous fuchsin. 



IV. Bacillus Anthracis. 



This bacillus is the specific cause of anthrax in cattle and the 

 so-called " wool-sorter's disease " in men. It occurs in rods, which 

 have truncate ends (slightly indented), and generally grow out 

 into long filaments. It produces a dry, easily-detached growth on 

 agar, and readily liquefies gelatin. Its movements are rotary. The 

 spores are ovoid, may be central or polar, and are very resisting, 

 having been known to live twenty years. It stains well with aque- 

 ous fuchsin or gentian- violet. 



