Marvels of the Universe 



o 



85 



THE EARTHWORM 



BV K. G. BLAIR, B.SC, F.E.S. 



Earthworms are perhaps the commonest 

 and most generally- known of all our native 

 fauna, yet it is truly astonishing how few 

 peop'e are acquainted in any detail with 

 their habits or realize how great are the 

 results brought about by their work. 



They prefer to live in moist earth, into 

 which the}- penetrate partly by thrusting in 

 their pointed heads and pushing away the 

 particles on either side, but mainly by 

 swallowing the earth as they go along, 

 passing it through their bodies, whence it 

 emerges at the tail end in the state of a 

 semi-fluid, fine comminuted mud. A con- 

 siderable quantit}' of this material is made 

 use of by the Worm to form a smooth, firm 

 lining to its galleries, an operation in which 

 the flattened tail plays the part of a trowel ; 

 the rest is brought to the surface and there 

 ejected in the form of the well-known worm- 

 casts. 



The body of the Earthworm is of fairly 

 simple structure, consisting of one long tube 

 within another. The inner tube is, of 

 course, the alimentary canal, the greater 

 part of which is formed bj' the intestine, 

 whose function it is to absorb nutriment 

 from the materials passing through it. In 

 man}- animals, ourselves for instance, the 

 intestine is long and coiled in order to in- 

 crease this absorbent area ; in the Earth- 

 worm it remains straight, but the sanre 

 object is attained b}' a great inward fold 

 along the back. This arrangement will per- 

 haps be better understood after a glance at 

 our fourth illustration, which represents a 

 section through the front part of a Worm. 

 The outer tube is formed by the skin and 

 muscles, while the space between the two is 

 crossed by a large number of transverse 

 partitions, and it is these partitions, seen 

 from without, that give the Worm its 

 characteristic ringed appearance. 



Its food consists mainly of decaying 

 leaves, which it pulls partly into its burrow ; 



I-linlnl,!!-] [II. M„in. F./:.S. 



THE COMMON EARTHWORM. 







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J'/,f./o /./'] [J. fl. Crahlree. 



PARI OF AN EARTHWORM'S BACK. 



In this photo of skin from an Earthworm's back magnified about 



thirty times the natural size, the rings and the apertures are shown 



clearly. From these pores a fluid is poured out that protects the 



worm from the attacks of bacteria. 



