This section of the book is from the "Household Companion: The Family Doctor" book
Tuberculosis is the implantation and growth of the tubercle bacillus in the tissues of a human being or an animal. The tubercle bacillus as a living entity conforms more nearly to the laws governing the vegetable kingdom than those governing the animal kingdom. It is rod-shaped about one six-thousandth of an inch in length and about one hundred-thousandth of an inch in thickness. It grows on the tissue as a parasite and ordinarily does not grow except upon the tissue of some living thing. It can be grown artificially in a laboratory on boiled potato, in beef tea and on agar, but it is difficult to grow in this way. It is only when it grows upon a living thing that the phenomena which it produces are called tuberculosis. The word tuberculosis is derived from the Latin word "tuber" which means a little root or lump. The name was given to the disease because the first stage of it is the production of little lumps.