Germ

that which germinates or grows. In medical science the term is used to mean a minute plant or animal, or a spore of the same. According to the germ theory, a large number of diseases, practically all contagious, are due to the poisonous influence of colonies of these organisms. A plant of this sort is a bacterium, plural, bacteria. An animal is a protozoon, plural, protozoa. Yellow fever and smallpox are, it is well believed, caused in this way; the former by a plant, the latter by animal colonies. A disease of this sort can be acquired only by taking germs into the system. Yellow fever or smallpox without germs are as impossible as a yield of wheat or chickens without seed or eggs. It has long been customary to speak of sowing the seeds of death and disease. The discovery of the actual germs of illness gives added force to the expression.

A careful farmer aims to keep foul seeds out of his fields. Preventive medicine, represented by boards of health and health officers, aims to keep the germs of disease out of the human system. Any agency that kills germs is a germicide. All germs are killed by heat. Some are killed by light, a few are ended by freezing, others live in ice. X-rays, radium, and electricity check, and possibly kill, certain microbes. Among chemical agencies that kill germs of one kind or another, chloride of lime, carbolic acid, alcohol, ammonia, formaldehyde, creosote, iodine, mercury, oils, mustard, cinnamon, peppermint, pennyroyal, quinine, borax, and salt may be named.

Under VACCINATION an account is given of the way in which the serum of the blood may be fortified against the germs of smallpox. The presence of weak germs seems to fill the blood with an antigerm element which prevents the future growth of germs of that sort. If soil be saturated with certain substances, as kerosene, seeds planted in it will decay instead of sprouting. It is possible, in the same way, to impregnate the blood with such an element that the germs of a specific disease will die instead of multiplying. This process is called inoculation. It consists in giving a person a mild form of the disease.

See Bacterium; Vaccination; Disinfectants, and articles on the various contagious diseases.