80 BRITISH EDIBLE FUNGI. 



moles, which loosened the soil and caused a more 

 fertile growth. Others have attributed them to 

 lightning, and others again to subterranean vapours ; 

 but the most feasible theory is that which is set forth 

 by the Rev. M. J. Berkeley, in the following words : 

 " These rings are sometimes of very ancient date, and 

 attain enormous dimensions, so as to be distinctly 

 visible on a hill side from a considerable distance. 

 It is believed that they originate from a single fungus 

 whose growth renders the soil immediately beneath 

 unfit for its reproduction. The spawn, however 

 spreads all around, and in the second year produces 

 a crop whose spawn spreads again, the soil behind 

 forbidding its return in that direction. Thus the 

 circle is continually increased, and extends indefinitely 

 till some cause intervenes to destroy it. If the spawn 

 did not spread on all sides at first, an arc of a circle 

 only is produced. The manure arising from the dead 

 fungi of the former years makes the grass peculiarly 

 vigorous round, so as to render the circle visible 

 even when there is no external appearance of the 

 fungus, and the contrast is often the stronger from 

 that behind being killed by the old spawn. This 

 mode of growth is far more common than is sup- 

 posed, and may be observed constantly in our woods 

 where the spawn can spread only in the soil, or 

 amongst the leaves and decaying fragments which 

 cover it." * 



* " Outlines of British Fungology," p. 41. 



