262 MORPHOLOGY OF INVERTEBRATE TYPES 



to your left. Make a drawing showing tunic, anterior or incurrent 

 siphon, posterior or excurrent siphon, dorsal surface between the 

 siphons and attachment area on opposite surface, also external ten- 

 tacles of siphons if not withdrawn (six incurrent, four excurrent). 



2. Remove tunic by making an incision with scissors and 

 tearing it apart with the aid of two strong forceps. Make a 

 drawing of the right side. Label circular and longitudinal 

 muscles on both siphons; the ganglion half way between the 

 siphons; the hermaphroditic gland lying across the body; the 

 more or less bean-shaped and transparent excretory organ under 

 hermaphroditic gland; the heart between them; the endostyle 

 (a white line along right edge of animal, ending in a circular 

 peripharyngeal groove); the brown liver on left, extending to 

 the edge of the animal. 



3. Make a drawing of the left side of the same specimen. 

 Label ganglion; endostyle; liver, oesophagus (a short tube be- 

 tween the lobes of the liver); stomach, intestine and left her- 

 maphroditic gland with duct. 



4. Support the specimen between two pins stuck into the 

 bottom of the tray and place it so that the incurrent siphon 

 would be directed away from you and the excurrent siphon above 

 it, presenting its sides symmetrically, with the plane of sym- 

 metry at right angles to the bottom of the tray. Make a drawing 

 showing all organs which are visible in this position, and label 

 anus, intestine, stomach, liver, oesophagus, both hermaphroditic 

 glands, edge of pharynx, and endostyle. 



5. Remove the right body wall, exposing the wall of the 

 pharynx and cloacal chamber. The operation is somewhat 

 delicate and care must be taken not to cut through the wall of the 

 pharynx. The right hermaphroditic gland, the heart and the 

 kidney should be removed together with the body wall. Make 

 a drawing showing peripharyngeal ridges with the stigmata; 

 cloacal chamber with anus and left genital opening in the depth; 

 liver; proximal end of oesophagus and valve separating it from 

 the pharynx; endostyle. 



