TTILITT Ain) DESTRUCTIOH" OF EEPTILES. 129 



that the worms had greatly increased in number, and that their 

 bores descended quite to the level of the pipes. Many worm- 

 bores were large enough to receive the little finger. A piece of 

 land near the sea in Lincolnshire, over which the sea had broken 

 and killed all the worms, remained sterile untU the worms again 

 inhabited it. A piece of pasture-land, in which worms were in such 

 numbers that it was thought their casts interfered too much with its 

 produce, was rolled at night in order to destroy the worms. The 

 result was, that the fertility of the field greatly declined, nor was 

 it restored until they had recruited their numbers, which was 

 aided by collecting and transporting multitudes of worms from 

 the fields. 



" The great depth into which worms will bore, and from which 

 they push up fine fertile soil and cast it on the surface, have been 

 well shown by the fact that in a few years they have actually ele- 

 vated the surface of fields by a large layer of rich mould several 

 inches thick, thus aJfording nourishment to the roots of grasses, 

 and increasing the productiveness of the soU." 



It should be added that the writer quoted, and all others who 

 have discussed the subject, have, so far as I know, overlooked one 

 very important element in the fertilization produced by earth- 

 worms. I refer to the enrichment of the soil by their excreta 

 during life, and by the decomposition of their remains when they 

 die. The manure thus furnished is as valuable as the like amount 

 of similar animal products derived from higher organisms, and 

 when we consider the prodigious numbers of these worms found 

 on a single square yard of some soils, we may easily see that they 

 furnish no insignificant contribution to the nutritive material re- 

 quired for the growth of plants.* 



I beheve there is no foundation for the supposition that earth- 

 worms attack the tuber of the potato. Some of them, especially 



* Since the publication of the previous editions of this work, Mr. Daxwin's 

 very recent observations on the earthworm have given to this humble form of 

 life a new importance. He has shown that the magnitude of the effects pro- 

 duced by these organisms, so individually insignificant, is vastly greater than 

 had hitherto been supposed — that they not only improve the soil, first by ma- 

 nipulating, then by their excreta and decay, as stated in the text, but that they 

 transplace it to such an extent as to be justly reckoned an important element 

 in superficial geography. 

 6* 



