Licence: Public Domain Mark
Credit: State control of tuberculosis. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![satisfuctorih prove or disprove the point at issue, ))ut, altli(nigh several hundred cases were reported, it was sliown in an ahle pjiper l)y Langstaff that they were not much more numerous than the coincident affection of the two persons could be expected to occur, accord- ing to the law of chance. It has, how^ever, been proved beyond question that among animals the dis- ease ma}^ be and is transmitted from one individual to another. The identity of the lesions in man and animals, and the fact of the universal presence of the bacillus in these lesions renders it certain that tuber- culosis in man also is a contagious disease.- There can be no question that tuberculosis is only caused hy the tubercle bacillus, and that the tubercle bacillus does except under extraordinary conditions, not, grow out- side of the human body. In order to grow tlie tubercle bacillus, it is necessary to exercise great care in the preparation of the culture medium. Furthermore, growth will very rarely take place except at the temperature of the body. The conditions are such that it can be said to Ije strictly ])arasitic in its habits of life. If any animal becomes infected, the germs must have been derived mediately or immediately from some other animal. While the bacilli do not grow outside of the l^ody, they may re- main alive for a considerable length of time. They are not, however, so resistant to destructive agencies as are many bacteria. Exposure to sunlight very speedily destroys them, sometimes in a few minutes. Drying, however, does not destroy them. Dried sputum has been shown to retain its virulence for three months, and doubtless, at times, will retain it for a much longer period. The bacillus is readily](https://iiif.wellcomecollection.org/image/b21226209_0013.jp2/full/800%2C/0/default.jpg)
