1889.] PUBLIC DOCUMENT— No. 4. 403 



facts have been well demonstrated by Koch in his numerous 

 experiments. Animals that are not susceptible to this dis- 

 ease will succumb to the direct inoculation of large numbers 

 of the bacilli. The period of incubation is an uncertain one, 

 as will be seen from the results of the experiments made by 

 Koch, varying as regards the amount of virus entering the 

 system, and the susceptibility of the animal. 



By artificial means this bacilli has been cultivated for eigh- 

 teen months, through twenty-six successive breedings, and 

 then found, by inoculation, to produce the morbid phenomena 

 of tuberculosis, the same as when taken from an infected 

 animal. This organism may gain its entrance into the system 

 by circulation, from the mother, respiratory or digestive 

 tracts, or through wounds on any part of the body. It has 

 been well said that contagious diseases in general, iind tuber- 

 culosis in particular, are very infrequent in habitations to 

 which strange cattle are not admitted, and where vacancies 

 are filled up by the home stock. 



The development of the disease depends upon the surround- 

 ings, condition of the animal, the organ or tissue involved, 

 and the amount of virus taken into the system. The first 

 evidence of infection is an elevation of temperature, which 

 often passes away in a few days unnoticed. 



The general condition of the animal will depend on the 

 progress that the disease has made so as to interfere with the 

 functions of the body. This will vary from the appearance 

 of perfect health to emaciation, with a rough, stary coat, and 

 hide-bound. Among other symptoms, there is an enlarge- 

 ment of the external lymphatic glands of throat, neck and 

 flank, and usually associated with disease in some of the 

 internal organs. Again, there is lameness without any evi- 

 dence of external cause, swelling of the joints, contraction of 

 muscles of the neck, and abscesses along the bones. 



Cases often present themselves with a cough, more or less 

 discharge from nostrils, hurried and labored respiration, or 

 even difficult . and audible respiration with a grunt. When 

 the digestive organs are the seat of the disease, capricious 

 appetite, bloating, tenderness on pressure, faeces soft or 

 constipated, and in last stages thin and foetid. The first 



