EARTH-WORMS AND THEIR WORKS. 



2 93 



burrow or for food, soon conies to the surface to empty its body. The 

 ejected earth is thoroughly mingled with the intestinal secretions, and 

 is thus rendered viscid. After being dried it sets hard. J have 

 watched worms during the act 

 of ejection, and when the earth 

 was in a very liquid state it 

 was ejected in little spurts, and 

 when not so liquid by a slow. 

 peristaltic movement. It is not 

 cast indifferently on any side, 

 but with some care, first on one 

 and then on another side, the 

 tail being used almost like a 

 trowel. As soon as a little heap 

 is formed the worm apparently 

 avoids, for the sake of safety, 

 protruding its tail, and the 

 earthy matter is forced up 

 through the previously depos- 

 ited soft mass." Some of the 

 towers, as the figure shows, ex- 

 hibit a considerable degree of 

 skill in their construction. The 

 castings are not always ejected 

 on the surface of the ground, 

 but are often lodged in any 

 cavity that may be met in 

 burrowing. The burrows run 

 down, sometimes perpendicu- Fk. 2 a Toweb-uke Casting, probably ejk 



. * * by a Species of Perich.eta (from the ho 



larly, generally a little oblique- 

 ly, to a depth of three, six, and 

 even eight feet, and are usually lined with a thin layer or plaster of 

 fine, dark-colored earth which the animals have voided, in addition to 

 which a lining is made, near the mouths, of leaves, also plastered. Bits 

 of stones and seeds are also sometimes found in the bottom of the bur- 

 rows, having been taken down apparently with a purpose. 



The amount of earth brought up by worms from beneath the sur- 

 face has been carefully estimated by observing the rate at which stones 

 and other scattered objects on top of the ground are buried. A piece 

 of waste, swampy land, which was inclosed, drained, plowed, harrowed, 

 and thickly covered with burned marl and cinders, and sowed with 

 grass, in 1822, fifteen years afterward, presented the appearance, where 

 holes were dug into it, shown by Fig. 3, the scale of which is half that 

 of nature. Beneath a sod an inch and a half thick was a layer of vege- 

 table mold, free from fragments of every kind, two and a half inches 

 thick. Under this was another layer of mold, an inch and a half thick, 



.TECTED 



by a Species of I'erich.eta (from the Hotanic 

 Garden, Calcutta : of natural size, engraved from a 

 photograph). 



