VII. 



FIELD-LABOURERS — Continued. 



* The plough is one of the most ancient and most 

 valuable of man's inventions; but long before he 

 existed the land was, in fact, regularly ploughed, and 

 still continues to be thus ploughed, by earthworms.' 



Earthworms are continually busy about this work 

 over pretty nearly the whole world, * reversing the 

 earth's crust, turning it over and over, from year to 

 year,' as the ploughman does, * only much more 

 slowly, and much more thoroughly, spadeful by spade- 

 ful, foot by foot, and even grain by grain.' And the 

 earthworm's work has another great advantage over 

 that of the ploughman. It is not only more thorough, 

 but it can be, and is, carried on even while the crops 

 are growing, and that without any material injury to 

 them. 



We have learnt much about the earthworm of late 

 years, thanks to Mr. Darwin; but long before 'Vege- 

 table Mould and Earthworms' was written — more 

 than a hundred years ago, in fact— Gilbert White, the 

 naturalist of Selborne, had a ver}' good idea of the 

 worm's importance as one of nature's field labourers. 

 *A good monography of worms,' he wrote, 'would 



