BOVINE TUBERCULOSIS. 63 



tubercular complicates the matter of determining whether or 

 not tubercle bacilli are found in milk from a healthy udder. 

 In the light of facts recently brought to attention, the discus- 

 sion of this matter of the udder in its relations to milk inspec- 

 tion is not very profitable../ 



{ I The manure of cattle contaminated with tubercle bacilli is 

 regarded as an important source of tubercle bacilli in milk. 

 Reacting tuberculous dairy cows that retain the appearance of 

 health, may actively expel tubercle bacilli in the feces (41, 42, 

 43, 46). A very small percentage of such cases in a herd could 

 bring about a very extensive infection of the milk. Among 

 the possible sources of the bacilli, understood at present, are 

 sputum swallowed, and open tubercular lesions of the intes- 

 tines. Feces constitute the most common contamination of 

 milk as demonstrated by observation of dairy practice, and by 

 the microscopic examination of milk sediments. The presence 

 of tubercle bacilli in human feces in early cases has been noted 



s^ and suggested as a means for the early diagnosis of the disease 



Xsi). 



r~~Tuberclc bacilli in market milk. Anderson (1) found in 

 /Washington, D. C., that 6.72% of 223 samples examined con- 

 I tained tubercle bacilli. The results analyzed according to the 

 source of the samples showed that about 11 $> of the dairies 

 whose milk was examined showed tubercle bacilli. His meth- 

 ods were such that he believes the results understate the true 

 conditions. 



Schroeder (43) refers to the examination of 350 samples of 

 milk in Washington by different workers with the result that 

 about 5.5% showed tubercle bacilli. About one dealer out of 

 every ten was intermittently selling tuberculous milk. Hess 

 (9) examined 107 samples of milk in New York and found 

 tubercle bacilli in 16% of the samples. Trask (Ref. 33, Chap. 

 Ill) has collected the results of the work on tubercle bacilli in 

 done by a large number of investigators. ^ 



Human and bovine types of tubercle bacilli. .( The original 

 ideas of the complete unity of tuberculosis in cattle and in 

 man were based upon the identity of the lesions in gross and 

 microscopic appearance. TUp to 1896, the identity of the 



