326 FUNCTIONS AND INSTINCTS. 



in the abdomen, but distant from the tail. By 

 these they fix themselves, living by suction ; 

 they sometimes produce fatal effects upon sheep. 

 When only in small numbers, they, doubtless, 

 as well as the rest of the Class, answer some 

 good end ; it is solely when they become 

 too numerous that they occasion fatal dis- 

 eases. Leeuwenhoek found 870 in one liver, 

 and in others only ten or twelve. He says 

 they occur in many kinds of quadrupeds, as 

 stags, wild boars, and calves. He seems quite 

 at a loss to account for their introduction into 

 the livers of these animals, but concludes that, 

 like the leech, their native element is water, 

 and their eggs, swallowed by cattle when they 

 drink, so find their way into the liver. This 

 of course is all conjecture. Providence, who 

 assigned to them their office, has also directed 

 them to their station, but from whence or by 

 what route we do not know certainly at present. 

 A friend of mine who has kept a flock for many 

 years, has observed that whenever they were 

 turned into moist meadows in wet seasons, they 

 suffered greatly from these animals ; but that in 

 the same situation, in a dry one, they were not 

 affected. 



The most celebrated of all the intestinal ani- 

 mals, are the Tape-worms, of which five species 

 have been ascertained to inhabit man, besides 

 whom quadrupeds, birds, reptiles and fishes are 

 equally their victims. These are now divided 



