152 PLANTS WITHOUT CHLOROPHYLL 



part of the food tube. Some in the food tube are believed to be 

 useful, some harmless, and some harmful ; others in the mouth 

 cause decay of the teeth, while ^a few kinds, if present in the 

 body, may cause disease. 



It is known that bacteria, like other living things, feed and give 

 off organic waste from their own bodies. This wa.ste, called a toxin, 



Tubercles on the roots of the soy bean. They contain the nitrogen-fixing bacteria. 

 (Fletcher's Soils.) Copyright by Doubleday, Page and Company. 



is poison to the host on which the bacteria live, and it is usually 

 the production of this toxin that causes the symptoms of disease. 

 Some forms, however, break down tissues and plug up the small 

 blood vessels, thus causing disease. 



Diseases caused by Bacteria. It is estimated that bacteria 

 cause annually over 50 per cent of the deaths of the human race. 

 As we will later see, a very large proportion of these diseases 

 might be prevented if people were educated sufficiently to 

 take the proper precautions to prevent their spread. These pre- 

 cautions might save the lives of some 3,000,000 of people yearly 

 in Europe and America. Tuberculosis, typhoid fever, diphtheria, 

 pneumonia, blood poisoning, diarrhea, and a score of other germ 

 diseases ought not to exist. A good deal more than half of the 

 present misery of this world might be prevented and this earth 

 made cleaner and better by the cooperation of the young people 

 now growing up to be our future home makers. 



How we take Germ Diseases. Germ or contagious diseases 

 either enter the body by way of the mouth, nose, or other body 



