DICROCCELIUM LANCEATUM STILES AND HASSALL 71 



the sections through (i) the cerebral ganglia, (2) the acetabulum, 

 (3) the anterior testis, (4) the posterior testis, (5) several succes- 

 sive sections following the end of the testis. Make diagram- 

 matic drawings of each of these sections to show the relative 

 position of the organs and of the various ducts. 



3. Additional exercise. Put a snail in a small dish with 

 water, break its shell, make an incision in the liver and collect 

 the escaping rediae and cercarias into the water. These larval 

 stages belong to other species of flukes than D. lanceatum and 

 may be readily procured if one has a sufficient number of snails. 

 Examine them while alive. They may be afterwards killed in 

 a sublimate fixing fluid and stained with haematoxylin. 



