156 



ZOOLOGY 



Another flat worm is such an abject parasite that it has 

 lost most of the organs usually possessed by worms. This is 

 the tapeworm (Fig. 147). When the eggs of the tape- 

 worm are taken into the body of an herbivorous animal, the 

 embryos develop there for a way and then stop. When 

 flesh containing these embryos is eaten by a carnivorous 



FIG. 146. Development of Distomum. A, ciliated larva ; B. sporocyst con- 

 taining developing rediae ; C, redia, containing a daughter redia and embryo 

 liver-flukes; D, free-swimming, tailed larva of liver-fluke; b. op, birth 

 opening; ent, food canal of redia; eye, eyespots; gast, young redia ; germ, 

 mor, early stages in formation of .the embryo liver-fluke ; int, intestine of 

 larval liver-fluke ; ces, oesophagus ; or. su, oral sucker; pap, head papilla of 

 ciliated larva, A; ph, pharynx; proc, processes of redia; vent, su, ventral 

 sucker. After Thomas. 



animal, the embryos attach themselves to the food canal of 

 their host and form, by rapid growth, a long chain of seg- 

 ments, each of which is full of germs. The chain, or 



