222 AUGUST. 



coming larger, have, of late years, been the 

 subjects of various theories. They have been 

 attributed to lightning, to fungi, which every 

 year grow upon the outer margin of the circle, 

 and then perishing, cause, by the rich remains, 

 a fresh circle of vivid green to appear, somewhat 

 wider of course than the former one. They 

 have also been attributed to insects. The least 

 plausible theory is that of lightning ; the most 

 plausible that of fungi. Insects are a conse- 

 quence of the fungi, rather than a cause of the 

 circle ; for where there are fungi there will be 

 insects to devour them. Fungi are also always 

 found more or less about them. I have seen 

 them of so large a species that, in their growth, 

 they totally destroyed the grass beneath them, 

 dividing the green ring into two, and leaving 

 one of bare rich mould between them. The 

 origin of these circles too, which hitherto has 

 escaped the eyes of the naturalist, but which 

 is nothing more than a small mushroom-bed, 

 made by the dung of cattle lying undisturbed 

 in the grass where first deposited, till it be- 

 comes completely incorporated with the soil 

 beneath, favours, more than all, the theory of 

 the fungi. Every one knows that where this 

 occurs, a tuft of rank grass springs up, in the 

 centre of which a crop of fungi sometimes ap- 

 pears, and again perishes. There then is the 



