346 THE EARTHWORM. 



and deteriorating our pastures. A few inches 

 of soil, resting upon a substratum of clay, would 

 commonly, without some natural or artificial drain- 

 age, be soaked with water after heavy rains, and 

 thus become a bog, or produce coarse water herbage, 

 rather than good grasses; but these worms greatly 

 facilitate the passage of the water by draining ho- 

 rizontally along the bed of clay, and aid the emis- 

 sion of the water by this means ; as I have often 

 observed in the trenches, which we cut in our reten- 

 tive soils, numerous worm-casts on their sides a few 

 days after they had been made, being the exits of 

 the horizontal runs ; and through these the water 

 drains into the trenches, and runs off. I do not 

 assert that water would not in any case be dis- 

 charged without the agency of worms, but that 

 the passages which they make expedite it ; which, 

 in situations where the operation would be sub- 

 jected to delay from the position of the ground, or 

 the under stratum, is of infinite advantage. Thus 

 the soil is not only rendered firm, allowing the ad- 

 mission of cattle, but the good herbage, which the 

 long residence of water would vitiate or destroy, is 

 saved from injury, and the aquatic and useless 

 plants starved or checked in their growth ; but 

 after great gluts of rain, when the supply of 

 water is greater than can be speedily carried off, 

 it becomes stagnant ; and those worms which can- 

 not burrow beyond its influence, soon perish, and 

 we lose the services of these very beneficial crea- 

 tures. Drainage is therefore one of the most 



