144 JOHNKS DISEASE 



due, no doubt, to coincident tuberculosis in the cow 

 from which the infected material was obtained. 



Inoculation Experiments with Pure Cultures of the 

 Bacillus. — When in 1910 the present writers obtained 

 pure cultures of Johne's bacillus on a special medium 

 (see Chapter VL), a series of animal experiments was 

 started. Care was taken to subculture the growths 

 for several generations, in order that cultures might 

 be obtained free from the diseased tissue that was 

 placed on the original tubes. The strain used was the 

 first that we isolated, and was obtained from the gland 

 of the naturally infected case No. 2 (see p. 71). In the 

 first instance we inoculated a cow and five calves, all 

 of which were obtained from a herd of cattle that had 

 been under the observation of a veterinary surgeon 

 for three years, during which period no case of Johne's 

 disease or any similar condition had occurred. One 

 calf died seventeen days after the inoculation, and need 

 not be considered further. Of the remaining cases, 

 each is described below individually and in detail. 

 Bovines Nos. i, 2, 4, and 5 are also referred to on p. 122. 



Bovine No. i. — A shorthorn cow about eight years 

 old and six weeks pregnant was tested in October, 

 1910, with ordinary tuberculin, and was found to be 

 free from tuberculosis. On November 19, 1910, the 

 animal was inoculated with a pure culture of Johne's 

 bacillus. The growth was eight weeks old, and the 

 third subculture distant from the original culture from 

 the mesenteric gland. The growth was made into an 

 emulsion with sterile o'8 per cent, sodium chloride, and 

 the whole given by the mouth to the cow, which had 

 had no food for twelve hours. No immediate symptoms 

 followed. From the time of feeding with the bacilli the 

 temperature of the animal was taken twice daily, and 

 it remained within normal limits, the averages for the 



