170 CHARLES DARWIN 



it pervious to rains and the fibres of plants, by drawing 

 straws and stalks of leaves into it ; and, most of all, by 

 throwing up such infinite numbers of lumps of earth, 

 called worm-casts, which, being their excrement, is a 

 fine manure for grain and grass. Worms probably 

 provide new soils for hills and slopes where the rain 

 washes the earth away ; and they affect slopes, probably, 

 to avoid being flooded. Gardeners and farmers express 

 their detestation of worms ; the former, because they 

 render their walks unsightly, and make them much 

 work; and the latter, because, as they think, worms 

 eat their green corn. But these men would find, that 

 the earth without worms would soon become cold, hard- 

 bound, and void of fermentation ; and, consequently, 

 sterile.' 



If Darwin ever read this interesting passage, which 

 he almost certainly must at some time have done, it 

 would appear that he had overlooked it in later life ; 

 for he, who was habitually so candid and careful in the 

 acknowledgment of all his obligations, however great 

 or however small, does not make any mention of it at 

 all in his ' Vegetable Mould,' though he alludes inci- 

 dentally to some other observations of Gilbert White's 

 on the minor habits and manners of earthworms. But 

 whether Darwin was originally indebted to White or 

 not for the foundation of his theory on the subject of 

 mould, the important point to notice is really this, that 

 what with the observant parson of Selborne was but a 

 casual glimpse, the mere passing suggestion of a fruit- 

 ful idea, became with Darwin, in his wider fashion, a 

 carefully elaborated and powerfully buttressed theory, 

 supported by long and patient investigation, ample 



