tentacles? How many tentacles in each circle? Which are the 

 longest? Are the tentacles hollow as in Hydra? 



(3) Medusoid buds, and medusae. Observe on sides of hy- 

 dranths various stages in formation of medusa buds. Where are 

 they attached ? Observe the structure of a fully formed bud, and 

 of a free medusa. 



Record your observations in labelled drawings. 



V. GONIONEMUS MURBACHII. (Hydro-Medusa). 



The three typical layers of the Coelenterata (ectoderm, endoderm 

 and mesoglea ) are represented. The mesoglea, however, has become 

 very thick. The bell-shaped medusa bears a large number of ten- 

 tacles from its margin. 



In the center of the bell is the manubrium, which bears on its 

 free end the mouth, the latter having tentacular folds. The opening 

 of the bell is partly closed by the velum. 



The digestive system consists of a short oesophagus in the manu- 

 brium leading into the stomach ; from the latter extend four radial 

 canals to the margin of the bell. At the margin, these radial canals 

 open into a marginal or ring canal. 



i he sexes are separate and the reproductive organs, both male and 

 female, are suspended from the radial canals. Fertilization takes 

 place in the water. 



VI. PLANARIA SP. (Turbellarian Worm). 



I. EXTERNAL ANATOMY. 



In the living worm distinguish between the anterior and posterior 

 ends, and the dorsal and ventral sides. Place an animal on a 

 slide with a drop of blood and observe the manner in which the 

 blood is sucked up and fills the digestive tract. Then place a fresh 

 drop of water on the animal and cover with a heavy cover glass. 

 Observe that the animal is covered with cilia. In the following 

 description make out as much as possible in the living animal, and 

 supplement this with a study of stained and mounted specimens, 

 both entire mounts and sections. 



II. THE DIGESTIVE SYSTEM. 



The mouth will be found at the extremity of a movable proboscis 

 which hangs from the mid-ventral line. The cavity of the pharynx 

 leads into that of the red-colored, branched intestine. The intestine 

 is seen to be made up of three divisions (Triclad type). One divi- 

 sion extends anteriorly and nearly reaches the dark colored eye 



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