140 BuKEAu OF Farmers' Institutes. 



told, and as we rise above mere assumption and scan closely every 

 bit of evidence, giving credence to nothing that is not warranted 

 by scientific investigation, indefatigably pursued to the end, that 

 truth may be established. Dr. Smith has demonstrated that 

 human bacilli grow more vigorously from the start than do those 

 from the bovine; that the length of the human bacillus is about 

 two to three times that of the bovine, in cultures; also other mor- 

 phological and biological characters in which they differ. More 

 convincing are the divergencies in their physiological effects, as 

 shown by his experiments, in which there was more rapid death 

 of all guinea pigs inoculated with bovine bacilli than those in- 

 oculated from human sputum. Experiments on rabbits con- 

 firmed those of the guinea pigs. His experiments on cattle by 

 the inoculation of bovine tubercle bacilli and human bacilli in 

 some ten cases shows " slight local lesions at the point where 

 the syringe was inserted when human sputum bacilli were used, 

 the disease not spreading. When the bovine bacilli were intro- 

 duced there was disseminated tuberculosis of the lungs, tuber- 

 cular deposits in lungs, ribs, pericardium and diaphragm, exten- 

 sive tuberculosis of nearly all the lymph glands of the thorax, 

 and slight tuberculosis of the spleen, liver and kidneys." These 

 differences are so great that comment is unnecessary. Dr. Smith 

 summarizes them in the following language: " The foregoing ex- 

 periments, while they show unmistakably the close relationship 

 existing among the various cultures studied, nevertheless justify 

 us, if only to guide and stimulate further study in establishing a 

 distinctively human, or sputum, and a bovine variety of the 

 tubercle bacillus." These modern experiments are infinitely 

 more reliable than those so often quoted of earlier investigators, 

 because our knowledge is greater, our facilities are better. I will 

 presently offer some practical evidence from the everyday lives 

 of people who are constantly exposed to the infection from bovine 

 tuberculosis. I know the cattle, know the percentage of diseased 

 animals in the herds, and have been aware of the existence of 

 disease in the herds for from several to eighteen years. I have 

 visited the people, dined with them when there were plenty of 



