Influence of Mushrooms on Growth of Some Plants. 321 



all the Basidiomycetes becomes available as food for autotrophic green 

 plants. This was anticipated since it is well known that in many proc- 

 esses of decay decomposition products are formed by the nutrient and 

 physiological action of micro-organisms, some of which are at once avail- 

 able as food for the autotrophs, while other decomposition products be- 

 come the prey of successive micro-organisms with different nutritive and 

 physiological demands so that the final products themselves become avail- 

 able. But it is rather surprising that the decomposition products from a 

 heterotrophic plant should form so nearly a perfect food for an auto- 

 troph. The decomposition of the larger fungi thus is seen to proceed 

 along the same general physiological lines as that of other organisms 

 which have been studied, the final products entering again into circulation 

 in the organic world. There is also probably a greater conservation of 

 the ammonia nitrogen in the decomposition of the mushrooms in nature 

 than in the case of the putrefaction of animal bodies because of the alka- 

 linity of the products of the latter compared with the acidity of the 

 products of the former. 



The chief ecological function of the mushroom is to disintegrate 

 leafy and woody structures without which action the world would in time 

 be choked with a deep layer of debris. These disintegrated remnants after 

 serving as food for many successive kinds of organisms with different 

 nutritive and physiological demands become available as food for auto- 

 trophs again, much of it in the meantime playing an important role in 

 improving the physical condition of the soil. But while this is their chief 

 ecological function they themselves are subject to similar decomposition 

 stages and again enter into the general nutritive circulation in the organic 

 world. 



It would be interesting to know if the symbiosis observed in the case 

 of certain fairy ring fungi growing in grass, where the grass in the ring 

 of mushrooms is greener than that on either side of the ring, has any 

 relation to available simple ammonia compounds formed by the mycelium 

 of the fungi. These might be obtained either from old portions of the 

 mycelium which have died and fermented, or through absorption by the 

 roots of the grass from living mycelium in contact. The results of this 

 study may also help to explain the method of nutrition of mycorhiza, 

 where the fungus symbiont from the humus and other organic matter 

 produces simple ammonia compounds as well as certain carbon com- 

 pounds, mineral substances, etc., which are passed on to the higher plant 

 whether a green plant or a chlorophylless one. In the latter case nearly 

 all the food may be supplied by the fungus symbiont. In the case of the 

 so-called saprophytic seed plants a similar relation may exist between 

 fungus mysilia not in contact, but within the area of root action pro- 

 21 



