166 THE BOOK OF NATURE STUDY 



destroyed by the antiseptic properties which it possesses. Should 

 the first line of defence prove inadequate, the worm has in reserve 

 a further weapon : from minute holes which open in the grooves 

 encircling the body, one hole in the middle of the back in each 

 groove, there gushes forth, when occasion demands, a watery 

 fluid in which float numerous corpuscles possessing powers of 

 independent movement. These corpuscles swarm around the 

 microscopic foe and destroy it. This flow may be provoked 

 artificially by putting a grain of some solid irritant, such as 

 corrosive sublimate or cayenne pepper upon the skin of the 

 worm. Simultaneously with the discharge of liquid from the 

 dorsal pores, it will be noticed that the worm's body becomes 

 much thinner both in front and behind the seat of irritation. 

 The appearance is as though a couple of ligatures had been tied 

 round the body in an attempt to isolate the affected segments 

 from the rest. The effect of the constrictions is to apply con- 

 siderable pressure to the fluids within the body, and so hasten 

 their discharge. 



Enemies from which the worm has no obvious means of escape, 

 except by retreat, are the mole ; certain subterranean slugs 

 (Testacella) which may be distinguished by the possession of a 

 small shell ; the reddish, flat-bodied centipedes, the " Devil's 

 coach-horse " beetles, and the grubs of some other beetles. 

 Certain flies also lay their eggs upon the bodies of worms, and 

 the resulting grubs devour the unfortunate victim. 



Food and Senses. The food, as already mentioned, largely 

 consists of decaying vegetable and animal matter in the soil ; 

 but living leaves are often attacked if they chance to be within 

 reach, those of the French bean being especial favourites. Since 

 worms possess no teeth it is necessary for them to soften the 

 substance of the leaf before they can tear bits off with their lips. 

 For this purpose slime is poured over the leaf from the front 

 portion of the body, and perhaps from the mouth. The slime 

 has the power of rotting and partly digesting the vegetable tissue, 

 so that subsequent removal by the lips becomes easy. This 

 effect of the slime may be seen if a worm is made to crawl over 

 a young leaf which is still attached to the plant ; after a day or 

 two the trail of the worm becomes evident as a brownish stripe 



