98 AGRICULTURE FOR BEGINNERS 



The little plants which make up these molds are called 

 fungi. Some fungi are quite large, as, for example, the 

 toadstools, puffballs, and Devil's snuff-box ; others very 

 small, as the molds ; and others even smaller than the 

 molds. Fungi never have the green color of ordinary 

 plants, always reproduce by spores, and feed on living 

 matter or matter that was once alive. Puffballs, for 

 example, are found on rotting wood or dead twigs or 

 roots. Some fungi grow on living plants, and these 

 produce plant disease by taking their nourishment from 

 the plant which they grow upon; the latter plant is then 

 called the host. 



The same blue mold that grows on bread often attacks 

 apples that have been slightly bruised; it cannot pierce 

 healthy apple skin. You can plant the mold in the bruised 

 apple, just as you did on bread, and watch its rapid spread 

 through the apple. You learn from this the need of pre- 

 venting bruised or decayed apples from coming in contact 

 with healthy fruit. 



Just as this fungus lives in the apple or bread, so other 

 varieties live on leaves, bark, etc. Fig. 83 represents the 

 surface of a mildewed rose leaf very greatly magnified. 

 This mildew is a fungus. You can see its creeping stems, 

 its upright stalk, and numerous spores ready to fall off and 

 spread the disease with the first breath of wind. You must 

 remember that this figure is greatly magnified, and that 

 the whole portion shown in the figure is only about one 

 tenth of an inch across. Fig. 84 shows the general appear- 

 ance of a twig affected by this disease. 



This mildew on the rose or on any plant so affected may 

 be killed by spraying the leaves with a solution of liver of 



