222 



THE FOOD OF ANIMALS 



Some of the compressed sandhopper-like forms (Amphipods) 

 and flattened woodlouse-like species (Isopods) also feed on vege- 

 table matter. We have, for example, the destructive wood-boring 

 Crustacean Chelura terebrans in the former group, commonly 

 associated with the Gribble (Limnoria lignorum), a species of 

 similar habit belonging to the latter order. Other vegetarian 

 Isopods are the little Water Wood- Louse (Asellns aquaticus], 

 which feeds chiefly on decaying leaves in ponds, &c., and the 

 Wood- Lice (species of Oniscus, Armadillium, &c.) (see vol. i, 

 p. 415), land-inhabiting creatures commonly found under stones. 

 In all these cases the mandibles are powerful, and well adapted for 

 breaking up the food. 



THREAD-WORMS (NEMATELMIA) 



The numerous phyla to the members of which the term 

 "worm" has been or may be applied include a very large 

 number of carnivorous forms, many animal parasites, and a crowd 

 of species which affect a mixed diet. Vegetarians pure and 

 simple are the exception. Carnivorous worms have already 

 been sufficiently dealt with (pp. 146-152), and those affecting a 

 mixed diet will be treated along with the forms of other groups 

 which are distinguished by similar feeding habits. In this chapter 

 it will only be necessary to mention certain Thread - Worms 

 (Nematodes) which attack plants, and often do serious damage. 



Other related forms live on 

 vegetable substances, but do 

 not attack living plants. A 

 well-known example of the 

 latter is the Vinegar- or Paste- 

 Eel (Anguillula aceti or Lepto- 

 dera oxophila). This often 

 abounds in paste or vinegar 

 which has "gone bad", that 



is tO 



i, Diseased spikelet of wheat; 2, eelworm (magnified); are growing. It is Upon 



3, young eelworm before hatching (enlarged); 4, diseased , . I'll* i i 



grain (enlarged); 5, the same in section, showing worms in that the CCl IS bellCVed tO SUD- 



interior. . . 1 . r i 



sist. A near relative of this 



harmless species is the Wheat -Eel worm (Tylenchus scandens) 

 (fig. 449), which infests the wheat plant, and stunts the growth 

 of the seedlings. Nor is this all, for the young worms get into 



