286 GENERAL BOTANY 



green plants, on account of their chloroplasts, are able to con- 

 vert the simple elements of the air and the soil into organic 

 food. For this purpose they are able to draw on the energy of 

 the sun through the agency of their chlorophyll pigment. Such 

 plants are thus able to secure an unlimited supply of outside 

 energy, which makes them the great food makers and accumu- 

 lators for the rest of organic nature. The colorless fungi and 

 the animals are dependent upon the green plants for organic food 

 and are therefore food destroyers and energy producers in the 

 organic world. Many of the green plants also serve directly as 

 food for animals and for parasitic fungi of various sorts, but 

 other green plants are not edible, or they die before they are 

 devoured by animals or by plant parasites. The food stored in 

 the cell walls and in the special storage organs of such plants 

 would be lost to the living organic world if it were not for the 

 saprophytic fungi. These saprophytes, as we have learned, are 

 able to secrete ferments which decompose by fermentation or 

 digestion the tissues of all lifeless organisms, and the result of 

 such decomposition is that all lifeless organic matter is ulti- 

 mately reconverted into the gases of the air and the salts of the 

 soil from which green plants obtain their raw food materials. 

 There is, therefore, a continuous cycle taking place in the world's 

 food supply, in which the green plants, the fungi, and the animals 

 are mutually interdependent and necessary factors. In this cycle 

 green plants are the great food producers and energy storers ; 

 animals and parasitic fungi are food users and energy pro- 

 ducers; and the saprophytic fungi are the great scavengers 

 and reconverters of lifeless organic matter into new compounds, 

 which can be used over again by the food-building green plants. 

 It is difficult to see how any one of the members of this triple 

 alliance of organic forms could exist for long without the pres- 

 ence of the other two members of the organic world. When we 

 take this larger view of nature, therefore, we see that the fungi 

 are, on the whole, useful plants. 



