Field-Labourers 79 



whereas, left upon the surface, they would benefit it 

 but little. Large earthworms sometimes bring up 

 soil from a great depth : in sandy soils, for instance, 

 their tubes go down from three or four to six feet, and 

 are then continued horizontally ; and the whole 

 contents of these tubes must, of course, be brought to 

 the surface. 



Estimates differ so much that it seems hopeless at 

 present to try and calculate their numbers. But this 

 one thing we know, there are many thousands in every 

 acre of moderately damp land, and, grain by grain, the 

 whole surface is literally 'loughed and saturated with 

 fertilizing juices. 



So far from being over-rated, as some have thought, 

 the earthworm is now proved to be an even more 

 valuable field-labourer than was supposed, and it is 

 said that, in estimating the value of land for farming 

 purposes, no satisfactory conclusion can be arrived at 

 unless the number of worm-holes be taken into the 

 account. 



Besides grinding up the soil in the process of 

 digestion to a state of extreme fineness, besides adding 

 to it vegetable matter and darkening its colour, worms 

 are most useful in another way : they prepare channels 

 through which the roots of plants are able to spread 

 with ease. Plants evidently prefer, when they can, to 

 take advantage of ready-made passages, and worm 

 burrows which have been in existence some little time 

 are usually found lined to the very end with fine roots 

 and rootlets, the latter covered with fine hairs, through 

 all of which the plant absorbs food. 



Roots of red clover have been found running down 

 six feet, or more, into the ground by means of these 



