Bacterium, a minute and exceedingly low vegetable form or monad, liable to appear in any fluid or solid substance containing vitalized matters. It is a mere point of organized matter, highly refractive, spherical in form, and moves with considerable activity. The first forms of living organisms, which M. Bechamp called microzymas, have been found in chalk, and are among the smallest living beings that can be seen. They are found also in concentrated alkaline solutions, in all the tissues of organic beings, in various morbid products, in the sugar-producing cells of the liver, in the blood of man and animals, in the liquids of the eggs, larvre, and perfect form of insects, in the sap of plants, and very extensively, if not universally, in the vegetable and animal kingdoms. They act as powerful organic ferments, as vegetable cells, in the transformation of cane sugar and fecula into glucose. They are derived from the air, in which the germs are in suspension, and undergo various degrees of development before they begin to act as ferments.

They undoubtedly play a very important part in both healthy and morbid processes; they assist in the ripening of fruits, in elabor rating certain matters for the nourishment of germs, in the constant regeneration of animal and vegetable organs, and in the formation and action of cells. They may, according to Bechamp, develop themselves and grow equally well in an acid, alkaline, or neutral menstruum. The normal microzymas, or organic granules, or molecular granulations, as they are called, in plants and animals, may develop into bacteriums, and many forms of both may exist in the same plant. The inoculation of bacterium in a plant or animal causes their increased number, not by multiplication, but by so modifying the medium that the normal microzymas more readily develop themselves into bacterium. Many of the phenomena of spontaneous generation find their explanation in these all-pervading and minute organisms. According to Bastian, while some of these monads originate by subdivision of preexisting individuals (homogenesis), others originate de novo, just as crystals by certain chemical laws.

He thus goes further than those advocates of spontaneous generation who believe that bacteriums originate by transformation of living matter (heterogenesis); for his mode of spontaneous generation he proposes the name of archebiosis. Torula) are very similar bodies, and are the germs of the yeast of fungus. Some bacteriums also may develop into fungi. (See Yeast Plant).