230 FORMATION AND GROWTH OF 



boggy nature again predominates, they disappear, so 

 that they cannot assist in making the upper stratum 

 of soil above the gravel ; moreover, if this upper 

 stratum is examined, it will be found to be of the 

 same platy or rudely laminated structure, as that 

 of all bogs that grow from the successive layers of 

 decayed vegetable matter. 



Those conversant with highly-cultivated, rich grass- 

 land, can scarcely have failed to remark the enormous 

 worm-work that yearly goes on ; but this is not the 

 case in all lands, for in many (not all) over chalk 

 and limestone there is little or no worm-work ; so 

 also in poor sandy soils, or in " slob-land " newly 

 reclaimed from the sea. On many chalk and lime- 

 stone lands " stones grow," or in other words, the 

 surface of some grass-land gradually becomes covered 

 with stones ; but in poor sandy soils, or in slob-land, 

 although it may be the work of time, yet eventually 

 there will be a surface-soil formed by the decay of 

 the vegetable matter, and all the stones will be 

 covered up by the growth of the soil. In such soils, 

 at the beginning of the growth of the vegetable 

 clothing, earthworms will be rare in fact, they 

 cannot live without organic food; therefore until 

 the vegetable life begins they cannot exist. As 

 the vegetable soil increases, so will the earthworms, 

 showing that the two agents work together, also 

 that the growth of the soil is due, not only to 



