. The human body and health : an elementary text-book of essential anatomy, applied physiology and practical hygiene for schools . isease-producing bacteria, after gaining en-trance to the body, sliall cause disease or not, depends upon the ability of the tissuesto destroy them. How Bacteria produceDisease. — Bacteria mustget into the tissues andmultiply in order to causedisease. They may findentrance through the ali-mentary canal, the lungs,or the skin. Germs likethose of tuberculosis andtyphoid fever may reachthe intestine with food orwater, and penetrate thecells there, and even passthrougl
. The human body and health : an elementary text-book of essential anatomy, applied physiology and practical hygiene for schools . isease-producing bacteria, after gaining en-trance to the body, sliall cause disease or not, depends upon the ability of the tissuesto destroy them. How Bacteria produceDisease. — Bacteria mustget into the tissues andmultiply in order to causedisease. They may findentrance through the ali-mentary canal, the lungs,or the skin. Germs likethose of tuberculosis andtyphoid fever may reachthe intestine with food orwater, and penetrate thecells there, and even passthrougli the walls of tlieintestine into the bloodto be carried to any partof the body. Throwingdead animals or waste matter into a stream of water is acrime, because the bacteria in them may cause disease anddeath to persons living along the stream and using thewater for drinking. With the air, bacteria enter thelungs when some of the ciliated cells lining the air tubesare injured. A break in the skin or even a faulty skingland may permit bacteria to reach the tissues beneathand produce a running sore; or blood poison may result. Fig. 29. — Germs that cause tuberculosisor consumption growing in clusters ap-pearing as white spots on a piece ofpotato smeared with glycerine. THE USEFUL BACTERIA 61 if they are carried through the system. Knives, needles,and dressings used in any operation, such as removinga splinter, or vaccination, should first beboiled to kill the germs on them. O Q (?) Bacteria injure the body in two ways. ©^OO They consume the tissue, and they give ^O off poisons. The bacteria causing boils fi^, 30.— Bacteriaeat away the tissues so as to form little ^^^^ cause boils. , Magnified. holes, but they do not give on muchpoison. The diphtheria bacilli do not destroy muchtissue, but excrete a great deal of poison, affecting theheart and other organs. The Useful Bacteria. — The souring^ of 0 c\L cream for churning, the flavor of some ^e\^0 cheese, the manufacture of
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