75O MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



The ointment is vigorously rubbed on a small portion of the skin of the 

 abdomen. A positive reaction is evidenced by the appearance of a 

 distinct granular or papular eruption at the point of application after 

 about twenty-four hours. 



For the diagnosis of tuberculosis in cattle, the intradermal test is 

 generally regarded as next in importance to the older subcutaneous test. 

 In conducting this test o.i to 0.3 c.c. of a 50 per cent solution of tuber- 

 culin is injected into the cuticle layer of the skin at the base of the 

 tail. A positive reaction is present when, twenty-four to seventy-two 

 hours after the injection of tuberculin, the localized area of skin shows 

 a circumscribed cedematous swelling. 



Tuberculin (old) is usually distributed in small vials, sealed and 

 labeled. The labels should indicate the amount and dosage and the 

 date of preparation. Under the influence of light and heat the fluid 

 product may slowly deteriorate; therefore, when possible, it should be 

 kept in the refrigerator until needed. 



Other Tuberculins. Koch introduced tuberculin "T. R." (tuber- 

 culin residuum) in 1897 and tuberculin "B. E." (bacillary emulsion) in 

 1901. The former is prepared by repeatedly centrifugalizing a suspen- 

 sion of the dried and ground tubercle organisms in water. The super- 

 natant fluid "T. O." after the first centrifugalization is discarded and 

 the final product consists of the constituents of the bacteria which are 

 insoluble in water. One cubic centimeter of the tuberculin "T. R." 

 should contain the equivalent of 2 mg. of the dry tubercle solids. 

 Tuberculin B. E. is composed of a suspension of crushed or thoroughly 

 ground tubercle organisms in 50 per cent glycerin solution. Each 

 cubic centimeter should contain the equivalent of 5 mg. of tubercle 

 solids. Tuberculin T. R. and tuberculin B. E. are used as therapeutic 

 agents, the latter probably being regarded with more favor by clini- 

 cians. The material is administered by subcutaneous injection, the 

 time intervening between successive treatments varying from three to 

 ten days. The initial dose recommended by most investigators, 

 is o.oooi mg. or less. 



MALLEIN. Mallein is prepared from cultures of Bact. mallei by 

 practically the same methods as those employed in manufacturing 

 tuberculin from Bact. tuberculosis. The product is used for the diag- 

 nosis of glanders. A few hours after mallein is injected, subcutaneously, 

 into glandered horses a severe local reaction and a rise of temperature 



