^86 



Marvels of the Universe 



# 



Photo ill] ill- -If"'!'- 



Egg-capsule of Earth- 

 worm. Each capsule con- 

 tains four eggs, 

 one produces 

 worm. 



but only 

 young 



but, in addition, the earth swallowed by the Worm in making its burrow is 

 acted upon bj- the digestive fluids in its passage through the body, and 

 the organic matter contained in it extracted. 



It is, of course, only at night that Worms become active ; during the 

 da}', especially if the atmosphere be warm and moist, they like to lie close 

 to the mouth of their burrows, concealed by a plug of leaves or heap of 

 castings, and the\' frequently line this part of the burrow with bits of leaf 

 or small stones, presumably to keep their bodies from direct contact with 

 the earth. They seldom entirely leave their burrows, but reach around as 

 far as they can, keeping the tail in the burrow ready for instant retreat. 

 For this purpose the rows of short, strong, retractile hairs along the body, 

 that are readily felt on pulling the Worm backwards through the fingers, 

 give it an excellent hold upon the sides of the burrow. Though they 

 usually confine their workings to w-thin about a foot or two of the surface, 

 yet in very cold weather, or in times of drought, they will penetrate to a 

 depth of four or five feet, and there construct a little chamber, which the}' line also with small 

 stones ; here they lie coiled up, often two or more Worms together in a knot, until more favour- 

 able conditions are resumed. 



Owing to the immense numbers in which Worms exist in the ground, the effect that they exercise 

 is considerable. In ordinary agricultural or pasture land the whole of the upper foot or so is being 

 continually passed through the bodies of \\'orms and brought to the top, thus, as it were, being 

 repeatedly though slowly " ploughed." The effect is not at once evident ; but when it is considered 

 that as castings are brought to the surface, burrows are formed below which sooner or later collapse, 

 and that this process is being continuously repeated, it will readily be perceived that in time the 



effect wiU be considerable. 

 Darwin, indeed, quotes nume- 

 rous instances &i a layer of 

 top-dressing of sand or lime 

 being laid on a field and a 

 number of years later a pit 

 being dug reveahng this layer 

 some distance below the sur- 

 face all round the pit. A large 

 number of observations show 

 that this burial takes place at 

 an average rate of rather over 

 one-fifth of an inch per annum. 

 The same explanation applies 

 to objects left on the ground — 

 stones, coins, etc. — being grad- 

 ually buried, and shows why a 

 stony field regularly ploughed 

 remains stony, but when left 

 for pasture becomes soft, even 

 turf, and why the floors of old 

 Roman houses and other ob- 

 jects of antiquarian interest 

 have lain protected beneath 

 a foot or so of earth. 



[J.H. Crahlree . 

 OF EARTHWORM. 



P!ioto iu'i 



SECTION _THROUGH "HEAD- 



The 'first four rings of the Earthworm are here magnified about twenty-two times, 

 to show, the simple mouth, 

 are nerve centres. 



The two darU patches, one above and one below the gullet. 



