No. 4.] CATTLE COMMISSIONERS. 565 



upon the public health, authorized me to use its laboratory facil- 

 ities, without which aid a further pursuit of the subject would 

 have been impossible. Some of the work was also done in the 

 newly established laboratory of comparative pathology of the 

 Harvard Medical School. 



A full report of this work, including a description of the method 

 employed for cultivating the bacilli of tuberculosis, the prelimi- 

 nary experiments upon small animals (rabbits and guinea-pigs) 

 and the microscopic study of the diseased tissues of the animals 

 experimented upon, will be given at another time. In this report 

 I shall restrict myself to that portion of the work having reference 

 to the immediate relationship and differences between human 

 (sputum) and bovine tubercle bacilli, as determined by experiments 

 upon cattle. 



Inasmuch as up to the time of the first experiment nothing was 

 known of the effects of bovine tubercle bacilli inoculated into 

 cattle, and very little, if anything, of the effects of tubercle bacilli 

 from man inoculated into the same species, the methods of deal- 

 ing with this subject had to be, as it were, developed during the 

 course of the work. One thing, however, was deemed essential. 

 The tests to be made with human and with bovine bacilli upon 

 cattle must be conducted under as uniform conditions as were pos- 

 sible, under the circumstances. Only by showing differences in 

 the action of tubercle bacilli from these two sources under the 

 same conditions can we prove any actually existing differences in 

 the bacilli themselves. Absolute uniformity was unattainable, but 

 I think the records will show with few exceptions a uniformity in 

 all important details. 



In all cases the various cultures of tubercle bacilli were isolated 

 by me. Cultures of unknown age and source, borrowed fi*om 

 others, were not employed. Products of the disease, tuberculous 

 tissue from cattle, in one case from swine, and sputum from human 

 subjects were inoculated into guinea-pigs, and from them, after 

 three to six weeks, cultures on dog's serum were obtained. These 

 were tested subsequently upon rabbits and guinea-pigs, and lastly 

 on cattle. 



The mode of testing the cultures upon cattle deserves a brief 

 description. In all cases the growth on blood serum was stirred 

 up in sterile bouillon until a clouded suspension was obtained, 

 which corresponded in depth to a bouillon culture of typhoid or 

 hog-cholera bacilli about twenty-four to thirty-six hours old. 

 This was injected with a hypodermic syringe into the thoracic 

 cavity through the right chest wall, the intent being to deposit at 

 least a portion of the suspension in the lung tissue. This method 



