160 WEiaHT OF EARTH Chap. in. 



" ground were so amazing, that if Mr. Miller 

 " had not seen them, he could not have 

 "thought it possible for such numbers to 

 " have existed in the space." As further evi- 

 dence of the large number of worms which 

 live in the ground, Hensen states that he 

 found in a garden sixty-four open burrows in 

 a space of 14i square feet, that is,. nine in 

 2 square feet. But the burrows are some- 

 times much more numerous, for when digging 

 in a grass-field near Maer Hall, I found a 

 cake of dry earth, as large as my two open 

 hands, which was penetrated by seven bur- 

 rows, as large as goose-quills. 



Weight of the earth ejected from a single 

 burrow, and from all the burrows within a 

 giiien space. — With respect to the weight of 

 the earth daily ejected by worms, Hensen 

 found that it amounted, in the case of some 

 worms which he kept in confinement, and 

 which he appears to have fed with leaves, to 

 only 0'5 gram, or less than 8 grains per 

 diem. But a very much larger amount 

 must be ejected by worms in their natural 

 state, at the periods when they consume earth 

 as food instead of leaves, and when they are 



