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THE POPULAR SCIENCE MONTHLY. 



certain quantity of earth. It eats its way, in fact, to the surface, and 

 there voids the material in a little heap. Although the proper diet 

 of worms is decaying vegetable matter, dragged down from the sur- 

 face in the form of leaves and tissues of plants, there are many occa- 

 sions on which this source of aliment fails, and the animal has then to 

 nourish itself by swallowing quantities of earth, for the sake of the 

 organic substances it contains. In this way the worm has a twofold 

 inducement to throw up earth : First, to dispose of the material ex- 

 cavated from its burrow ; and, second, to obtain adequate nourishment 

 in times of famine. "When we behold a wide, turf-covered expanse," 

 says Mr. Darwin, " we should remember that its smoothness, on 

 which so much of its beauty depends, is mainly due to all the ine- 

 qualities having been slowly leveled by worms. It is a marvelous 

 reflection that the whole of the superficial mold over any such ex- 

 panse has passed, and will again pass, every few years, through the 

 bodies of worms. The plow is one of the most ancient and most 

 valuable of man's inventions ; but long before he existed the land was, 

 in fact, regularly plowed by earth-worms. It may be doubted 

 whether there are many other animals which have played so important 

 a part in the history of the world as have these lowly organized 

 creatures." * 



Now, without denying the very important contribution of the 

 earth-worm in this respect, a truth sufficiently indorsed by the fact 



' SINGLY OR IN CLUSTERS.' 



that the most circumstantial of naturalists has devoted a whole book 



to this one animal, I would humbly bring forward another claimant 



to the honor of being, along with the worm, the agriculturist of na- 



* " Vegetable Mold and Earth-worms," p. 313. 



