322 ANNUAL REPORT OF THE Off. Doc. 



tion under what may be considered more or less natural conditions. 

 The list of animals in which tuberculosis has been observed in parks 

 and zoological gardetis is appalling, the discoveries of Dubard^ and 

 others showing that not even the coldblooded animals are exempt 

 from this universal scourge. While it may be said of the tubercle 

 bacillus that in cultures in the laboratory it is unusually tenacious of 

 its characteristics, it is certain that in nature it has a wide range 

 of adaptability as a pathogenic agent. Hence for the tubercle 

 bacillus, perhaps more than for any other knov>'n microbe, we are 

 justified in believing that an exaltation of virulence for practically 

 all experimental animals will hold good in the case of man also. 



The question can be determined definitely only by direct inocula- 

 tion of man. To do this experimentally is of course impossible, con- 

 sequently we are forced to rely for evidence of this nature on those 

 accidental cases which occur from time to time. It has been my 

 fortune to have three such cases come utider my observation, in 

 each of which the infecting organism was known positively to be of 

 bovine origin.^ Similar cases have been reported by Tscherning'^ and 

 rfeiffer,* the latter ending in general infection and death. To these 

 may be added two cases observed by Dr. M. B. Hartzell,^ of the Uni- 

 versity of Tennsylvania, though in both, absolute proof of the bovine 

 origin of the offending organism is lacking. Both occurred in 

 h.ealthy men employed by one of our large American railways to 

 clean and repair cars used in the transportation of cattle. In both 

 a well-developed tuberculosis of the skin followed slight wounds of 

 the back of the hand inflicted by broken timbers. In one case the 

 local disease was soon cured and no further trouble resulted. The 

 other, however, ended fatally after about a year, through the infec- 

 tion becoming generalized, with involvement of the lungs. This 

 patient was a robust man, forty-four years old, weighing 175 pounds, 

 with good family and personal histories. Dr. Hartzell felt able to 

 exclude with reasonable certainty any other source of infection. 



Cases such as these permit us to deny with authority the claim 

 which has been made by certain persons that by long residence in 

 animals of the bovine species the tubercle bacillus becomes so 

 changed as to render it incapable of successful residence in the 

 tissues of man. In all of these instances the bovine bacillus grew 

 and multiplied under conditions known to be most unfavorable to 

 it, with (he production of characteristic lesions, and in two of the 

 seven cases gained access to the internal organs, causing death, a 

 result which is unusual when the local lesion is due to infection from 

 human sources. While the number of cases is too small to enable 

 us to di-aw sweeping conclusions, the indications are that by this 

 mode of inoculation the pathogenic power of the bovine bacillus is 

 at least as great as that possessed by its human congener. 



Infection through Food. — It will not be necessary here to review 



