144 BIOLOGY FOR BEGINNERS 



pp. 343-353; Scientific Features of Modern Medicine, Lee, pp. 86-109; 

 Community Hygiene, Hutchinson, pp. 233-247; Handbook of Health, 

 Hutchinson, pp. 286-313; Immune Sera, Bolduan and Koopman, look 

 through; Infection and Immunity, Sternberg, look through; General 

 Biology, Sedgwick and Wilson, pp. 192-201; General Science, Caldwell 

 and Eikenberry, pp. 79-101 



SUMMARY 



Definition: minute, one-celled, parasitic, fungous plants. 

 Kinds, coccus (round); bacillus (oblong); spirillium (spiral). 



" Germ or microbe" may be either plant or animal forms. 



" Bacteria" applies only to plants. 



Characteristics: 



Size. 



Rate of reproduction (why limited). 



Favorable conditions: food, moisture, warmth. 



Occurrence. 



Methods of Study. 



1. Sterilization of apparatus (why necessary). 



2. Making of "culture medium" (a sterile, moist food supply). 



3. Inoculation with forms to be studied. 



4. Growth of bacterial "colonies," on the medium. 



5. Selection, and making of " pure cultures." 

 (Explain precautions taken in canning fruits.) 



Useful forms of Bacteria. 



1. Nitrogen fixers on clover roots (why useful). 



2. Scavengers and decay producers (why useful). 



3. Forms necessary in following processes: 



Souring of milk, making of cheese. 

 Fermentation of alcohol, vinegar, etc. 

 Tanning leather. 

 Preparing hemp and flax. 



Harmful forms of Bacteria. 



(See list of bacterial disease in text.) 



One-half all deaths, one-seventh by tuberculosis. 



Those causing food decay. Plant blights. 



Natural defences against bacteria, etc. 



1. Skin and mucous membranes (clean, whole and healthy). 



2. Natural bodily resistance, secured by 



General good health. 

 White corpuscles (destroy germs). 

 Antitoxins (oppose bacterial poisons). 

 Opsonins. 



