The regions of the body which are usually the seat of a primary tuberculosis are unquestionably the respiratory and intestinal tracts. With regard to the first of these regions, the one most frequently affected, there can be no doubt that in most instances the inhaled air carries the bacilli or their spores, or both. Their constant presence in the sputum of the frequent cases of tuberculous phthisis suggests a ready means for their escape into the atmosphere. The well recognized infective qualities of the sputum, as demonstrated by the various experiments before the bacillus was discovered, demand the thorough disinfection of phthisical sputa, since these are in all probability the chief source of the dissemination of the disease. The tuberculosis of the intestine in like manner is to be regarded in the main as the result of an absorption from its surface of the specific agent. An obvious direct means of the approach of the bacilli is offered in the sputum, which, when swallowed, is likely to retain its virulent properties. The frequent coexistence of chronic pulmonary and intestinal tuberculosis is thus most readily explained. To what extent the presence of the bacilli in the pearly distemper of cattle and in the tuberculosis of other edible domesticated animals, as fowls and swine, may lead to an infection of the intestinal wall, still remains an unsolved problem. It is not yet determined at what temperatures the bacilli are destroyed, although their growth takes place only between 30° C. (86° F.) and {105} 41° C. (105.8° F.). The inoculation of pearly masses produces tuberculosis in certain animals, yet the effect of cooking in destroying the bacilli and their spores is likely to prove of great importance. Aufrecht's[76] attempts at inoculating rabbits with cooked pearly masses proved unsuccessful. Schottelius[77] publishes an interesting series of observations relating to the prolonged use of meat from cattle affected with the pearly distemper, and shows that after a period of years no disease of the nature of tuberculosis occurred among the one hundred and thirty individuals included in the families concerned. Whatever may be the value of this negative testimony, there is, as yet, no evidence on the other side which satisfactorily determines the point in question--viz. that the flesh of animals affected with pearly distemper produces tuberculosis in the human consumer. [Footnote 76: _Op. cit._, 51.] [Footnote 77: _Virchow's Archiv_, 1883, xci. 129.]