WORMS. 175 



yet their motions are very different. The ser- 

 pent, as has been said before, having a back- 

 bone which it is incapable of contracting, bends 

 its body into the form of a bow, and then shoots 

 forward from the tail ; but it is very different 

 with the worm, w r hich has a power of contracting 

 or lengthening itself at will. There is a spiral 

 muscle that runs round its whole body, from the 

 head to the tail, somewhat resembling a wire 

 wound round a walking cane, which, when slip- 

 ped off, and one end extended and held fast, will 

 bring the other nearer to it ; in this manner the 

 earth-worm having shot out or extended its body, 

 takes hold by the slime of the fore part of its 

 body, and so contracts and brings forward the 

 hinder part : in this manner it moves onward, not 

 without great effort, but the occasions for its pro-r 

 gressive motion are few. 



As it is designed for living under the earth, 

 and leading a life of obscurity, so it seems toler- 

 ably adapted to its situation. Its body is armed 

 with small stiff sharp burrs or prickles, which it 

 can erect or depress at pleasure ; under the skin 

 there lies a slimy juice, to be ejected as occasion 

 requires, at certain perforations between the rings 

 of the muscles, to lubricate its body, and facilitate 

 its passage into the earth. Like most other in- 

 sects, it hath breathing-holes along the back, ad- 

 joining each ring ; but it is without bones, with- 

 out eyes, without ears, and properly without feet. 

 It has a mouth, and also an alimentary canal, which 

 runs along to the very point of the tail. In some 

 worms, however, particularly such as arefound in 



