CONCLUSIONS. 



This paper is intended as a preliminary report and as more data is 

 obtained, these conclusions may be modified somewhat. They arc 

 given merely as a summary of results thus far obtained. 



(1) Bovovaccine fails to protect calves until two and one-half 

 years old, under California conditions. Some immunity seems to be 

 produced. 



(2) Tuberculosis will sometimes spread rapidly in cattle under 

 strictly outdoor conditions. 



(3) The retesting of cattle within six weeks, even when Vallee's 

 method is used, is unsatisfactory. Some tubercular cattle will not 

 react to tuberculin on retesting even after three months. 



(4) Numerous microscopic examinations, by Rosenberger's 

 method, of blood sediments from twenty tuberculous cattle, failed to 

 give evidence that tubercle bacilli existed in the circulating blood. 



(5) In one instance tubercle bacilli were recovered from blood 

 drawn twenty-five minutes after inoculation of the arterial blood- 

 stream. 



(6) Guinea- pig inoculations with the blood sediments of twenty 

 tuberculous cattle failed to produce tuberculosis. 



(7) Tubercle bacilli which have been experimentally thrown into 

 the blood-stream are rapidly removed from the circulation. Experi- 

 ment suggests that the capillaries of the lungs are more efficient in 

 arresting bacilli than the peripheral capillaries. 



(8) Judging from two instances only, cattle affected with chronic 

 tuberculosis seem much more resistant to acute tuberculosis from 

 inoculation than one-tubercular cattle. Chronic tuberculosis in 

 cattle appears to produce a partial immunity against fresh inocula- 

 tion with bovine tubercle bacilli. 



University Farm, Davis, California. 



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