94 RESEARCHES ON FUNGI 



good to eat as wild ones and were even more satisfactory for the 

 table on account of their larger size. The swollen stipes of the 

 abnormally large fruit-bodies were perfectly palatable and there- 

 fore did not need to be discarded when the fruit-bodies were being 

 prepared for the pot. 



J. S. Bayliss made an investigation upon the fairy rings of 

 Marasmius oreades and came to the conclusion that the fungus 

 is a parasite. She states that the mycelium attacks the young 

 roots of grasses and kills them by means of some toxic excretion. 1 

 On the other hand, Shantz and Piemeisel, who made an extended 

 study of a number of very large fairy rings produced by several 

 species of fungi in Colorado, are disinclined to believe that the 

 mycelium of fairy-ring fungi is in any sense parasitic, and hold that 

 the death of the grass-plants and other herbs in the bare zones 

 of the rings in dry weather is simply due to excessive local drought 

 caused by the resistance of the subjacent mycelium-infected soil 

 to the absorption of water and the passage of water into the roots. 2 

 Unfortunately, these observers did not examine the living plants 

 among which the mycelium was growing in order to find out whether 

 or not their roots were being entered and killed by the hyphae. 

 Now it is known that there are a number of soil-fungi (Imperfecti) 

 which do, as a matter of fact, attack and kill some of the roots 

 of cultivated Gramineae such as Wheat and Maize. It seems to 

 me not unlikely, therefore, that the mycelium of certain fairy-ring 

 fungi, such as Marasmius oreades, should kill roots also, and it 

 need be no matter for surprise if the observations of Bayliss should 

 be confirmed and extended. I wish to point out here, however, 

 that Marasmius oreades, whether parasitic or not in pastures, can 

 certainly live as a pure saprophyte under artificial conditions, 

 for as such a pure saprophyte it lived for five years in the bed of 

 manure at Winnipeg. The bed, as already mentioned, was kept 

 free from weeds so that the mycelium of the fungus never once had 

 the chance of developing at the expense of living grass-plants. 



1 Jessie S. Bayliss, " Observations on Marasmius oreades and Clitocybe gigantea 

 as Parasitic Fungi," Journal of Economic Biology, 1911, vol. vi, pp. 120, 130. 



2 H. I. Shantz and R. L. Piemeisel, " Fungus Fairy Rings in Eastern Colorado 

 and their Effect on Vegetation," Journal of Agricultural Research, 1917, vol. xi. 

 pp. 236-237. 



