DEPENDENT PLANTS 



109 



for example, the heaths, oaks, apples, and pines. It is 

 probable that the fungous threads perform some of the 

 offices of root-hairs to the 

 host. On the other hand, 

 the fungus obtains some 

 nourishment from the 

 host. The association 

 seems to be mutual. 



Saprophytes break 

 down or decompose or- 

 ganic substances. Chief 

 of these saprophytes are 

 many microscopic organ- 



FiG. 135. — Bacteria of Several 

 Forms, much magnified. 



isms known as bacteria (Fig. 135). These innumerable 

 organisms are immersed in water or in dead animals and 



plants, and in all manner of 

 moist organic products. By 

 breaking down organic 

 combinations, they produce 

 decay. Largely through 

 their agency, and that of 

 many true but microscopic 

 fungi, all things pass into 

 soil and gas. Thus are the 

 bodies of plants and animals 

 removed and the continuing 

 round of life is maintained. 

 Some parasites are green- 

 leaved. Such is the mistle- 

 toe (Fig. 136). They anchor 

 themselves on the host and 



absorb its juices, but they 

 Fig. 136. — American Mistletoe ' ■' 



GROWING ON A WALNUT BRANCH. also appropriate and use 



