242 



Nature-Study Agriculture 



Flies as 

 carriers 

 of germs 



Fungi and 



bacteria 



compared 



consumption, another kind multiplying in the throat 

 produces diphtheria, and still another variety whose 

 natural home is in the digestive organs is the cause of 

 typhoid fever. Disease germs are often carried on the 

 feet of flies from filth upon which the flies have rested, 

 to food upon the table, and it is for this reason prin- 

 cipally that flies should be exterminated (page 183). 



Fungi. Fungi are plants that lack chlorophyll, and 

 therefore, like most bacteria, they are dependent on ani- 

 mal or vegetable matter for food. As with bacteria also, 

 there are beneficial and harmful forms of fungi. Some of 

 them aid in the process of decay or cause mold. Others 

 grow upon the bodies of insects such as chinch bugs, grass- 

 hoppers, and flies, causing the death of untold numbers 

 of these pests. The yeast that is so important in bread- 

 making is a fungus, and it is different varieties of fungi 

 that give the distinctive flavors to various kinds of 

 cheese. Though many fungi are so small that we need 



the aid of a microscope to 

 study them, others, as the 

 mushrooms and puff balls, grow 

 to considerable size. We have 

 seen that bacteria are tiny 



FIG. 193. Bread mold, showing the rootlike parts that absorb food from the 

 material on which the mold grows, the filaments by which the mold spreads, and 

 upright filaments on which spores have formed. 



