BUGULA 



87 



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 relations to each other? Where are the empty cups 

 found? Explain. 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 for the 

 mouth. 



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

 there food in the stomach? 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? 



