VEGETABLE EXCRETION. &1 



of luxuriance of the grass follows as a natural con- 

 sequence ; for the soil of an interior circle will 

 always be enriched and fertilized with respect to 

 the culture of grass, by the decayed roots of fungi 

 of the preceding year's growth. It often happens, 

 indeed, during the growth of these fungi, that they 

 so completely absorb all nutriment from the soil 

 beneath, that the herbage is for a time totally de- 

 stroyed, giving rise to the appearance of a ring 

 bare of grass, surrounding the dark ring; but after 

 the fungi have ceased to appear, the soil where 

 they had grown becomes darker, and the grass 

 soon vegetates again with peculiar vigour. When 

 two adjacent circles meet, and interfere with each 

 other's progress, they not only do not cross each 

 other, but both circles are invariably obliterated 

 between the points of contact ; for the exhaustion 

 occasioned by each obstructs the progress of the 

 other, and both are starved. It would appear that 

 different species of fungi often require the same 

 kind of nutriment; for, in cases of the interference 

 of a circle of mushrooms with another of puff-balls, 

 still the circles do not intersect one another ; the 

 exhaustion produced by the one being equally de- 

 trimental to the growth of the other, as if it had 

 been occasioned by the previous vegetation of its 

 own species. 



The only final cause we can assign for the series 

 of phenomena constituting the nutritive functions 

 of vegetables is the formation of certain organic 

 products calculated to supply sustenance to a higher 

 order of beings. The animal kingdom is altogether 

 dependent for its support, and even existence, on 

 the vegetable world. Plants appear formed to bring 



