This section of the book is from the "Household Companion: The Family Doctor" book
These are all very minute, and only visible by the microscope, and their presence on or in the body is only judged from the diseases which they set up. They attack either the external or internal parts of the body. They may be all included under the one head of germs or micro-organisms. These are small, generally microscopic organisms of the lowest forms of vegetable life.