Anatomy, physiology and hygiene for high schools . hese organisms are alive and growand multiply. Many of them are every-where about us, in the air and soil andwater, and within our own , like most of those bacteria whichcause special diseases, as typhoid feveror smallpox, are not generally distribu-ted, but are found only in regions wherethese diseases have been, or in substanceswhich have come from such regions. The manner of action of bacteria is that of fermentation,described on page 267 and also in Chapter VII. When the bacteria act upon the dead plants or deadanimal tissues
Anatomy, physiology and hygiene for high schools . hese organisms are alive and growand multiply. Many of them are every-where about us, in the air and soil andwater, and within our own , like most of those bacteria whichcause special diseases, as typhoid feveror smallpox, are not generally distribu-ted, but are found only in regions wherethese diseases have been, or in substanceswhich have come from such regions. The manner of action of bacteria is that of fermentation,described on page 267 and also in Chapter VII. When the bacteria act upon the dead plants or deadanimal tissues lying about on the ground, they break upthese substances into simpler substances. So also when thebacteria of disease enter and effect a lodgment in our bodies,they break down our tissues in the same manner. Some of the common diseases caused by these bacteriaacting in this way are diphtheria, consumption, scarlet fever,measles, whooping cough, typhoid fever, smallpox, andprobably influenza. In diphtheria (Greek diphtJiera, parchment—membranes. SpirilH Bacteria. 270 PHYSIOLOGY AND HYGIENE resembling parchment are formed in the throat in this dis-ease), for instance, the httle rod-shaped bacilli which causethis disease lodge in the membrane of the pharynx orlarynx, and feeding upon the body substances, grow andmultiply. Thus feeding, they irritate and decompose the tis-sues and set up inflammation and necrosis (that is, death ofthe tissue cells) therein, so that the membrane of the throatbecomes swollen and disintegrated. The throat becomesvery sore, and the passages are often obstructed by the in-flammatory products formed. At the same time, in thusfeeding upon and disintegrating the tissues, the bacteria pro-duce or bring about the production of poisonous substances(toxines), which are absorbed into the system and make thepatient very ill with fever, headache, nausea, and othersymptoms. All these processes, the inflammation in the throat andthe absorption of the poison, may
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