BRANCH VERMES. 



particular interest. While still attached in one' of the 

 bile-ducts, it constantly sets free a multitude of eggs, 

 which follow the duct to the intestine, from whence 

 some finally reach damp earth or pools. 

 There they hatch and give rise to active little 

 eyed forms, which, on coming in contact 

 with the soft parts of certain snails, thrust 

 themselves through the skin and become 

 encysted. After some time, one of these 

 cysts may break open, as the snail crawls 

 over the grass, and give birth to not one, 

 but several active forms, each of which en- 

 cysts on a blade of grass. A sheep, grazing, 

 swallows the encysted animal, which the di- 

 gestive juices bring into activity, and we 

 finally have the completed cycle in the 

 adult Fluke, which produces in sheep the 

 disorder popularly known as " rot." 



M 



- " 



~ a 







o - 

 X 



II 



ORDER CESTODA (ses to'da). 



The Tape-worms also belong to this class. 

 Several species of these worms are found in 

 the intestines of various animals. Here we 

 meet with a parasite, even more degraded 

 than the Fluke. As the animal floats in 

 the digested matter of the alimentary tract, 

 it takes in its nourishment by absorption 

 through the skin of its body. No mouth is 

 present, though there is usually a number of hooks, and 

 in some species, suckers, on the anterior portion of the 

 body, the "head," by which it remains attached. Behind 

 the head, and stretching back, in some forms for twelve 

 feet, is the flat ribbon-like and jointed body, constantly 



