ANIMAL PARASITES 251 



should be used for pasturing horses and cattle, but if possible, 

 it should be first drained and cultivated. Careful feeding and 

 good care may help the affected animals to recover. 



Tapeworms or Cestoides. — Taj^eworms are formed by a 

 chain of segments, joined together at their ends, and are flat or 

 ribbon-shaped (Fig. Tl). The head segment is small, and 

 possesses either hooks or suckers. It is by these that the worm 

 attaches itself to the lining membrane of the intestine. The 



Fig. 73. — Tapeworm larvse in thu ijentuueum {Cysticercus cellulosa) , 



anterior segments are smaller and less mature than the posterior 

 segments. Each segment is sexually complete, possessing both 

 the male and female organs, and when mature, one or more of 

 them break off and are passed out with the fa?ces. The mature or 

 ripe segments are filled with ova. On reaching the digestive 

 tract of a proper host, usually with the drinlving water or fodder, 

 the embryo is freed from the egg. The armed emhryo uses its 

 booklets in boring its way through the wall of the intestine. It 

 then wanders through the tissues of its host until it finally 

 reaches a suitable place for development (Figs. 71 and 73), On 



