80 
THE GEOLOGIST. 
" As the, worms desert their old burrows, the soil sinks in and fills them ; 
and by this means a constant cii-culation is continued, the vegetable mould ex' 
tending itself do\vnwards, whUe the 'dead soil' — that is, tlie ])urcly mineral 
matter — is brought up, and so the cultivable staple increases. If we examine 
even tlie uiunoved gravel in tlie pit, wherever it is not too deep below the 
surface, we sluill find that the worms arc invading it, eating out the sand 
between the stones, running their excavations down in favourable places, 
plastering them, too, round the sides with the peculiar slime and earthy matter 
with which they puddle them to keep out the wet, and leaving their excrement 
in them ; thus gradually changing the colour of the mass, and making it fit for 
the roots of the herbage above to strike into. 
" It is believed to be a mistake, however, to suppose that the growing vege- 
tation is supported chiefly by vegetable decay. A certain essential portion of 
its carbon — that is, its vegetable matter — the rising plant, it is thought, must 
thus obt ain ; but it is dependent upon the atmosphere for its chief supply, 
having the power of elaborating carbon from it by means of its leaves. What 
the plant specially wants from the soil is mineral matter ; and tliis the earth- 
worm keeps withm its reach, by continually transferring it from below upwards, 
in a properly comminuted state. Every shower that falls washes away some of 
this valuable matter, as anyone may see who will watch the rUls which trickle 
over the surface at the time ; and if the rain is heavy, it carries off a great 
quantity of clay and sand. The unavoidable consequence of this natural 
operation would be that the upper layer would consist chiefly of the coarser 
materials, the larger grit and stones, which wovdd be ill adapted for the sup- 
port of the more valuable kind of herbage. But the earthworm supplies the 
waste ; and in this way is an agent of which geology must take notice ; 
for denudation and its consequences — the fiUiug up of valleys and lakes, the 
growth of deltas at the mouth of rivers, and the accumulation of strata on the 
sea-bottom — would all go on more slowly if the worm did not bring up fine 
matter to the suiface for the rain to sweep off." 
We have not space in this number to notice very minutely Mr. Eley's book ; 
and indeed it is not essential that in reviewing we should descend into parti- 
culars. It wiU sidfice then to add a plan of the work. From the fliut-peDbles 
in his garden our author passes to a consideration of the Chalk formation and 
the great physical changes to which the Wealden area of the south-east of 
England has been subjected. 
In treating of the origin of those remarkable bands of siliceous nodules which 
mark the upper beds of our English chalk, however, Mr. Eley throws no addi- 
tional light, and leaves that difficult question as he found it. 
From the physical events of this region we are passed on to the boulder-drift 
and to stiU. more expanded views of the general physical conditions of our 
globe itself. Then are so naively brought forward the habits and operations 
of the earth-worm to which we have so pointedly alluded. The concluding 
chapter developes the author's view that the changes indicated by Geology 
reveal part of a fore-ordamcd plan for preparing the earth's surface for the 
occupancy of man. For ourselves we have derived both pleasure and instruction 
from Mr. Eley's book, and there arc but few wliich it has fallen to our lot to 
read, that we could recommend to oar readers so sincerely, or with so much 
pleasui'e. 
