4-0 



THE PLANT WORLD. 



vestigation, however, the assigning- of a reasonable cause for this 

 curious phenomenon was demanded, and among the first attempts 

 was one very ingenious explanation. According to this theory the 

 ring marked the spot where a lightning stroke had" descended into the 

 earth. It was assumed that the lightning bolt was of the same 

 diameter as the ring, and that only where the lightning bolt came in 

 contact with the air, namely, along its surface, did combustion take 

 place. Therefore as the bolt descended into the ground it burned a 

 ring of grass, and this dead vegetable matter, acting in following years 

 as a fertilizer, stimulated the new grass to a dark green growth. So 

 great indeed, according to this theory, was the fertilizing elTect that a 

 certain kind of mushroom very often grew along the dark green 

 band. This theory, however, did not explain why it was that the 

 same fairy-ring increased in size from year to year. 



It is now well established that fairy-rings are caused by the mycel- 

 ium of various kinds of fungi, the best known species being the common 

 fairy-ring mushroom [Marasiuius arcades). (See fig. i. ) The mycelium, 



starting at a central point, grows out- 

 wardly in all directions and at a remark- 

 ably uniform rate. Soon the older and 

 central portion dies. Thus a small circular 

 band is formed which each year increases 

 in size, growing regularly on the outside 

 and dying as regularly on the inside. The 

 width of the band is commonly about six 

 inches, while the diameter of the ring 

 often reaches six and eight feet, some- 

 times even twenty feet. Seldom is a ring 

 complete after the first few years of its 

 life, an opening almost invariably develop- 

 Sometimes 



FIG. 



ing on the down-hill side. 



such a large part of the ring dies as to 



leave only a crescent. 



A few days after a soaking rain, fol- 

 lowing a drier period, the mushrooms 

 themselves push their way up through 

 the grass and expand their caps. The 

 stem and upper surface of the cap have a 

 pinkish buff color, while the gills are of 

 a lighter shade of the same, varying in 

 the younger stage to warm cream-color. 

 The spores are white. It should be noted 

 (See figs. 2 and 3) that the stem does 



FIG. 3. 



