BACTERIA 



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BACTERIA 



Each kind reproduces its kind. Typhoid fever 

 and tuberculosis are caused by bacilli; Asiatic 

 cholera by spirilla; and pneumonia by micro- 

 cocci (pneumococci) . 



Kinds of Bacteria. It is because bacteria 

 growing in our bodies result in many diseases 

 that people now hear so much about bacteria. 

 There are really two kinds. One kind or group 

 feeds on dead animal or vegetable matter, the 

 other kind only on living matter. Bacteria of 

 the second class (see PARASITES) are the more 

 harmful. Although the former may be malig- 

 nant, they are doing good in that they are 

 destroying dead matter and decomposing it 

 into its elements. But bacteria which live on 

 living things destroy other lives to nourish 

 their own; they are doing harm. Nearly all 

 infectious diseases are known to be caused by 

 bacteria. The few, including measles and scar- 

 let fever, not known to be caused by bacteria, 

 are believed to be caused by them, but the 

 specific germ in each case has not yet been 

 discovered. This is probably due to the fact 

 that the germs in question are too small to 

 be seen even under a powerful microscope. See 

 DISEASE, subhead Germ Theory of Disease. 



How to Kill Bacteria. Strong sunlight is a 

 powerful germ killer, provided it acts long 

 enough. Its power is lessened when it passes 

 through glass; it is therefore best to sun things 

 out-of-doors. Freezing and drying are uncer- 

 tain methods of killing bacteria, for the organ- 

 isms supposedly dead may be only lying quiet 

 in their latent form. Heat, especially moist 

 heat, is a sure way to destroy germs. Boiling 

 milk or water or cooking meats and vegetables 

 always destroys these harmful organisms and 

 prevents any possible infection. This is the 

 reason why health authorities should always 

 warn people to boil their drinking water if 

 the source of supply has been infected in some 

 way. As a rule, milk which has been carefully 

 handled from the start need not be boiled 

 so long that its character and taste are affected, 

 as ordinary germs are destroyed with moderate 

 heat. Long-continued boiling, however, which 

 greatly changes both its taste and nutritive 

 qualities, is the only sure way of rendering 

 milk absolutely sterile. Certain so-called 

 germicides or disinfectants, such as alcohol and 

 carbolic acid, also put an end to germs, but 

 many advertised proprietary germicides are 

 worthless. See ANTISEPTIC; ANTITOXIN. 



Bacteriology. Bacteriology is the study of 

 the character, development and effects of bac- 

 terial growth, with especial reference to human 



Outline and Questions on 

 Bacteria and Bac- 

 teriology 



I. Characterititioa 



(1) Vegetable organisms 



(2) Size 



(3) Flagella 



(4) Classes 



(a) Bacillus; rod-shaped 



1. The germ of typhoid fever 

 and tuberculosis 



(b) Spirillum; long, curved or 



spiral 

 1. The germ of Asiatic cholera 



(c) Micrococcus ; spherical 



1. The germ of pneumonia 



(5) Where found 



II. K in, is of Bacteria 



( 1 ) Those feeding upon dead animal or 



vegetable matter 



(2) Those feeding upon living matter 

 (a) Germs of most infectious dis- 



III. The Destruction of Bacteria 



(1) By strong sunlight 



(2) By moist heat 



(3) By disinfectants 



IV. Bacteriology 



(1) The study of bacteria causing 



human diseases 



(2) Methods of studying these organ- 



isms 



(3) Means of getting a "pure culture" 



(4) Ways of determining the kind of 



germ 



Questions 



What do the bacteria that cause 

 typhoid fever look like? 



Why does not milk taste the same 

 after it has stood for several days? 



Can all kinds of bacteria be grown 

 in the same substance? 



What characteristics led scientists to 

 suppose at first that bacteria were ani- 

 mal organisms? 



Do different kinds live together in a 

 single colony? 



What advantage has the back yard 

 over the sun-parlor as a place for sun- 

 ning things? 



Can ' any physician tell what the 

 germs of scarlet fever and measles 

 look like? 



How are bacteria specimens mounted 

 for study? 



What method may be used to render 

 milk perfectly sterile? 



