44 MORPHOLOGY OF INVERTEBRATE TYPES 



most, add a drop of glycerine and cover with a cover glass. Ex- 

 amine the covering of the exumbrella under high power (400 

 diameters). Choose a protuberance with some exploded nem- 

 atocysts and make a drawing showing an entire protuberance 

 with all nematocysts. 



6. Examine a tentacle on the same slide and make a drawing 

 showing the rings of nematocysts. 



7. Cut off a piece of a mouth-arm, place it on a slide in a drop 

 of glycerine, cover with a cover glass and examine under high 

 power (200 diameters). Make a drawing showing the tentacles 

 with the nematocysts evenly distributed over them, and the 

 brood-pouches with embryos. 



8. Cut off a piece of the floor of a gastric pouch with gastric 

 filaments, put it on a slide in the same manner as in the preceding 

 exercise and examine under high power (200 diameters). Make 

 a drawing of a gastric filament showing the cavity and the walls 

 with nematocysts evenly distributed over them. 



