THE TAPEWORM 135 



Development. — (i) The rediae, one of the stages of 

 development of the Fluke, may be found in the liver of 

 the common pondsnail, Limnoea. Break the shell of the 

 snail and remove the animal. Place the body of the snail 

 in a shallow dish of water, and with the aid of the dissect- 

 -ing microscope pick the liver to pieces with dissecting 

 needles. This will probably free the rediae. 



Note their size and shape. Do you find a mouth f A 

 pharynx f An intestine? Eyes? Do they need eyes ? Draw 

 (Xio). 



(2) Do you find germ cells, or young rediae inside the 

 animal ? Draw. 



When we find an animal living upon another, deriving its 

 nourishment from the latter, the former is called a parasite 

 and the latter its host. Explain how this applies in case of 

 the snail and the fluke. 



Note. — This animal has a very interesting life history, which may 

 be worked out by the students from references or given by the 

 teacher in a lecture. 



THE TAPEWORM 



(i) The Tapeworm is found in the alimentary canal of 

 the rat, the cat, the dog, the rabbit, and many other verte- 

 brates, including man. Sufficient supply for class use may 

 generally be obtained by killing a dog or a cat and looking 

 at once for tapeworms. Open the intestine for one or two 

 feet, beginning at the stomach. Scrape the wall of the in- 

 testine closely so as to secure the heads which are buried 

 in the tissue of the canal. They may be kept alive for 



