VICTORY AND REST 169 



and manners strove to show how the entire existence of 

 vegetable mould the ordinary covering of fertile soil 

 upon the face of the earth is due to the long but un- 

 obtrusive action of these little-noticed and ever-active 

 architects. By the acids which they evolve, they appear 

 to aid largely in the disintegration of the stone beneath 

 the surface ; by their constant practice of eating fallen 

 leaves, which they drag down with them into their 

 subterranean burrows, they produce the fine castings of 

 soft earth, so familiar to everybody, and thus reinstate 

 the coating of humus above the bare rock as often as it is 

 washed away again in the course of ordinary denudation 

 by the rain and the torrents. It is true that subsequent 

 investigation has shown the possibility of vegetable 

 mould existing under certain conditions without the 

 intervention of worms to any marked extent ; but, as a 

 whole, there can be little doubt that over most parts of 

 the world the presence of soil, and therefore of the vege- 

 table growth rooted in it, is entirely due to the unsus- 

 pected yet ceaseless activity of these humble creatures. 

 The germ of the earthworm theory appears to me to 

 have been first suggested to Darwin's mind by a passage 

 in a work where one would little have suspected it 

 White's ' Natural History of Selborne.' ' Earthworms,' 

 says the idyllic Hampshire naturalist, 'though in ap- 

 pearance a small and despicable link in the chain of 

 nature, yet, if lost, would make a lamentable chasm. 

 For to say nothing of half the birds, and some quad- 

 rupeds, which are almost entirely supported by them, 

 worms seem to be the great promoters of vegetation, 

 which would proceed but lamely without them, by 

 boring, perforating, and loosening the soil, and rendering 



