BACTERIA

or germs, are microscopic fungi. The number of species already known is so great that there are obably as many ies in nature as there are different finds of flowering ~ Bey Just as in flowering plants we find some adapted to the water, the mountain, the valley, the equator or the poles, so amongst bacteria we find tho same range of habitat, the samo varicty of usefulne or harmfulne to man, the same wide range from extreme vitality to comparative delicacy. Air, earth and water, our skin, our clothes, and our mouths are all tenanted by bacteria of this species or that. Fortunate indecd is it that most of them are harmle , for the few specially adapted for preying on man cause more suffering and premature death than almost anything else. Boils, gangrene, festering wounds, erysipelas, lockjaw, consumption, and the various infectious fevers are each caused by the ravages of (Lowe species of germ. Indeed so great a danger is only kept in check by a most elaborate system of defence; the — as they gain entrance to the body are attacked by the white corpuscles, and their poisons are neutralised are formation within the body of antidotes specially pted to each. This means of defence extends far down the animal scale, becoming simpler and le efficient as tho lower forms of animal life are reached. Plants enjoy a comparative immunity from the attack of Hacterlag teh only to fall a ready prey to numberle parasitic moulds. ao ioreapery of disease, however, is the work of only a section of the bacteria, of in fact a few aberrant forms specialised to a parasitic life. The chief work of bacteria is to cause putrefaction, without which life would soon be papomitle, as we should be buried beneath the dead leaves the dead animals of a former age. Another group Bap to make soil by fixing the nitrogen of the atmosphere changing it to nitrates, which are a valuable manure. This kind live attached to the roots of clover and other leguminous are a fact which the farmer now turns to account in the rotation of crops. Others again tan leather, make vinegar and ripen cheese, though others turn milk sour and butter rancid, whilst yet others live in our intestines and aid in the digestion of food and in the removal of any exce that may be taken. In short, bacteria are good servants but bad masters. [Refer to Disinfection] [s. 334]