This section of the book is from the "Household Companion: The Family Doctor" book
The contagion of tuberculosis is always contained in broken down tissue given off by the person who has the disease. Usually this tissue is thrown off in the form of spit but sometimes it is given off in the form of matter. When a consumptive coughs he may spray out some of this matter in his cough and he may do the same when he sneezes. The contagion is not in the breath, however. A tuberculous subject is not contagious until he begins to give off broken down matter, because there is no contagion except in this broken down matter. A tuberculous subject who gives off broken down matter can make himself non-contagious by properly disposing of that matter immediately when it is given off. The dangerousness of the consumptive, therefore, depends upon his habits. If he spits around promiscuously or if he spits into handkerchiefs or rags and smears himself all over with the sputum he is a dangerous person to have around, but if he spits into a sputum cup which he holds close to his mouth, and if he always holds a paper napkin to his mouth when he coughs and sneezes and puts that paper napkin into a bag where he cannot smear anything, he is entirely safe.