How the germ of tuberculosis was discovered
About thirty years ago, Dr. Robert Koch discovered that all consumptives have in their sputum a long, slender germ which he called the tubercle bacillus. Some of these germs he injected into guinea pigs, and he found that they caused the pigs to have consumption. Then he made many other experiments, and proved beyond question that it is this very germ that causes tuberculosis, and that no one has consumption unless he has this germ in his body.
Evidence that consumption is not inherited
Then the question arose, "Is the baby whose parents have consumption born with this germ in its body?" This question could not at first be answered; but tests were made by taking the children of consumptive parents away from their parents, and keeping them in homes where there were no consumptives. It was found that these babies did not develop the disease. From these and many other tests, it has been proved that consumption is not inherited, and that the reason the child of the consumptive so often has consumption is because he lives with people having the disease.
Evidence that consumption is a house disease
Consumption seems to be confined to certain families, and this has led many people to think that the disease is inherited, regardless of the proof that it is not. When we carefully study the facts in various cases, we find that the disease is not confined to a certain family, so much as it is to the house in which the family lives.
The record of a single house will illustrate how tuberculosis sticks to the house rather than to the family. From 1880 to 1901, a particular house was occupied by a father, mother, and six children, of whom four died of consumption. From 1902 to 1903 the house was occupied by another father and mother with eight children. They moved away because of the great amount of sickness in the family. At present this father and one of his children have tuberculosis. In 1904 the house was occupied by still another family, consisting likewise of a father, mother, and eight children. Now it is known that four of the children have tuberculosis, and it is feared that three others have also contracted the disease. In 1905 a son of the first occupant, with his wife and two children, returned to live in the house. The father of this family died of tuberculosis. Up to 1906 the total results from this house, scattered through four families, were as follows: five deaths, six cases in people still living, and three suspected cases.
Fig. 66. The constant danger of infection in railway cars, where germs can live as well as in a house.
Why consumption is a house disease