FUNGI 



1«T 



host organisms. The great work of fungi in nature is thus to 



break down organic matter and return the elements to Mother 



Earth, that they niay be caught up in tlie circle of food supply 



and live ac^ain. Without this beneficent work of the funo-i 



all the animals and plants 



that have died since the 



beGfinnino-s of life in the 



world, if they had not been 



eaten or burned, would still 



cumber' the earth ; that is, 



the food of the world would 



be locked up in dead forms. 



Burnincf returns the nitro- 



gen 



to the air. 



a most 



wasteful process, — while 

 the decay of the dead bod- 

 ies and Avaste matters of 

 animals and plants caused 

 by fungi holds this most 

 precious of all foodstuffs 

 in chemical combination as 

 nitrates, ready again to be 

 built up into the grains, 

 seeds, fruits, and other food 

 products of green plants 

 (see Chapter IX). Thus, 

 in burnino- wheat straw the 

 farmer may rob liis land 

 of twenty-five pounds of 

 nitrogen in combination, Avorth $3.75 per acre per year, and 

 an acre of corn stover or cotton stalks may contain respec- 

 tively $7.50 and $15.30 worth of nitrogen. Where it is cus- 

 tomary to burn these materials is it any wonder .that the wheat, 

 cotton, and corn fields are worn out? 



A7TR4TES 



Fig. 00. Circulation of protein food 

 materials in nature 



Nitroijenons food (protein) is tlio one essen- 

 tial food of both aiiiiiials and i>lants. The 

 green plants build up this entire food sup- 

 ply from the cheuiii-al elements by the 

 energy of suidiulit AAorking tlirough leaf 

 green, or chlorophyll; nn repri'sents free 

 nitrogen from the air, drawn into combi- 

 nation by symbiotic bacteria in the root 

 tubercles of clovers, beans, etc. The non- 

 nitrogenous foods — starches, sugars, gums, 

 fats, and oils — are built up along Avith the 

 proteins .and are tinally oxidized to carbon 

 dioxide and water. MJietljer in tbe animal 

 or plant body or by rotting or burning 



