BUGULA. 65 



aid of a glass-bottomed pail in the positions they occupy on the 

 sides of the piles of almost any old wharf. What must be the 

 source of their food? What part of the colony is likely to be 

 best nourished? Collect specimens by scraping the piles and 

 see what forms are associated with them. 



1. Examine a colony in a dish of water and see how it 

 branches. Does it present any regularity? 



Make a drawing of a colony. 



2. Remove one of the flat branches, place it in a watch-glass 

 of water, and examine it with a low power. What more can be 

 observed regarding the branches? How are the cups arranged? 

 Are the cups on the two sides of a twig placed in definite rela- 

 tions to each other? Where are the empty cups found? Why? 

 Can you find connections between the cups of the two sides? 



Make a drawing showing the arrangement of the cups. 



3. Allow a living branch to remain undisturbed for a few 

 moments and with a microscope see how the thin outer mar- 

 gins of the cups are unfolded as the zooids protrude. 



4. Mount a specimen on a slide, cover, and compare the 

 tentacles of an expanded zooid with those of the hydroids that 

 you studied. How do they differ? How must the animal feed? 



5. How are the tentacles arranged around the distal end of 

 the body? How many tentacles are there ? Look ior the mouth. 



6. Can you see the parts of the alimentary canal? Is there 

 food in the stomach f How does the zooid pull itself back into 

 its cup? 



7. Look for avicularia and observe their movements and 

 structure. Where is the jaw hinged? Where are the muscles 

 that open it? Where are the muscles that close it? Of these 

 muscles, which are largest? Why? See if ''sense hairs" can 

 be found between the jaws. What is their probable use? 



Draw an avicularium. 



8. Ooecia with embryos will be found in some specimens. 

 Where are they placed? 



9. Put powdered carmine in the water with a living branch 

 and see if the zooids will eat it. 



5 



