228 



AGRICULTURE 



during a few weeks of damp weather, which makes most 

 germs of plant diseases grow more rapidly. No matter 

 how damp the weather, there will be no peach-rot unless 

 the spores or seed bodies are first sown. A few fungi are 

 useful. Some kinds sour milk so that it can be churned 

 into butter ; others, called yeasts, cause flour bread to rise ; 

 while still other kinds are necessary in making vinegar. 



EXERCISE. Secure some half-ripe sound peaches and place two or 

 three of these under tumblers. At the same time find one which is de- 

 cayed and shows upon the surface tufts of a gray mold. Now with a 

 pocket knife touch the mold tufts of the diseased fruit and make cuts 

 in the healthy peaches. Wrap the scratched peaches in a damp news- 

 paper and put them under a can or cup in a warm place. Do they rot? 



FIG. isj.-^- 



APPLES, THE RESULT OF THOROUGH SPRAYING 



