No. 6. DEPARTMENT OF AGRICULTURE. 319 



bacilli in the emulsion tlian those injected with the sputum, we are 

 led to conclude lluit the result in the latter was due (o a mixed in- 

 fection which operated to the advauta^e of the tubercle bacillus. 



The attempt to infect calves with human sputum by the digestive 

 tract failed wholly. Two young calves (Table V, Nos. 8074 and 8096) 

 were given from 30 to 00 c.c. of sputum containing many tubercle 

 bacilli on eleven days. Some disturbance of digestion resulted at 

 the time, but when killed no trace of tuberculosis was detected.* 



Indications for Further Investigation.— In the further elucidation 

 of this question, cultures should be isolated from as many cases of 

 primary intestinal tuberculosis, and especially those cases in which 

 there is reason to suspect infection by meat or milk. Having ob- 

 tained the cultures, it may well be asked whether or not we are in a 

 position to determine positively the origin of the offending organ- 

 isms. Are the differences which have been noted in culture, mor- 

 phology and virulence, sufficiently marked and persistent to make 

 dift'erentiation possible? This 1 doubt. In ray judgment much 

 more work must be done before we shall be able to determine the 

 origin of a given culture of the tubercle bacillus by examination of 

 it in cultures. At present we know practically nothing of the in- 

 fluence of the human body on the tubercle bacillus, nor what changes 

 may be induced in its morphology, cultural peculiarities and viru- 

 lence by residence in the human tissues, nor what length of time is 

 necessary to induce such chasiges, if induced at all. In my studies I 

 have, as shown in Table III, recovered the tubercle bacillus, both 

 human and bovine from horses, dogs, swine, goats, and in one in- 

 stance had the rare if not unique opp)ortuuity of recovering the 

 bovine organism from man after accidental inoculation. These re- 

 covered cultures have all been carefully compared with the originals, 

 and while some differences have been observed, and noted in the 

 remarks following the table, with possiblj' one exception, they have 

 not been of a marked or distinguishing character. In the case of 

 the man the bacillus remained in his tissues from January 1 to Feb- 

 ruary 27, fift^-eight days. The recovered culture was practically 

 identical with the original. This is, however, a shorter time by a 

 great deal than elapses between intestinal infection in children 

 through food and their death, and does not enable us to draw con- 

 clusions as to these cases. Like the culture recovered from animals, 

 it indicates that the tubercle bacillus is quite tenacious of its char- 

 acteristics, as a rule. "We have noted constantly that the bacilli 

 found in scrapings from the various organs of the animals inoculated 

 with bovine cultures have been long and beaded though the culture 

 used was of the short and unbeaded type. The recovered cultures, 

 however, on blood-serum have always resembled the original. In 



*This experiment was conducted by Dr. W. G. Shaw, to whom all the credit 

 is due. 



