LABORATORY EXERCISES I 25 



100. Porifera (Sponges): 



(a) Study a simple sponge like Grantia. Note the general form, 

 the point of attachment, the large excurrent opening or osculum 

 and the spicules. 



(b) In a dry specimen of Grantia cut longitudinally, note the central 

 cavity or cloaca and the radial canals. Note also the form and 

 arrangement of all spicules. 



(c) A longitudinal section treated with acid to remove the spicules 

 and then stained and mounted will show the relation of the 

 radial canals and the incurrent canals or interradial spaces. 



(d) A dry specimen in cross section should be studied in connection 

 with b. 



(e) A cross section with the spicules, stained and mounted, will 

 show further details especially with regard to the arrangement 

 of spicules and may also show ova or embryos. 



(f) The spicules may be set free by dissolving the fleshy parts in 

 boiling potash. How many kinds of spicules are there? 



loi. Cnidaria: 



(a) A sea anemone (Metridium). In a lateral view note: the col- 

 umn, the base, the crown of tentacles. 



(b) In an oral view note the mouth with the grooved lips and 

 siphonoglyph (one or two). 



(c) In a cross section through the middle of the column note: 



1. The gullet with grooves and siphonoglyphes. 



2. The gastro-vascular cavity incompletely divided into cham- 

 bers by the mesenteries. 



3. The mesenteries are of two kinds, complete and incomplete 

 and on their edges may be found the mesenterial filaments 

 and acontia and the gonads. 



(d) Study a fragment of a coral (Astrangia). The cups (theca) each 

 contain a central columella and a number (?) of radial septa. 



102. Platyhelminthes: 



(a) In a living planarian note the method of locomotion, the eye 

 spots, the proboscis. 



(b) In an adult liver fluke note the terminal mouth and the ventral 

 sucker. 



(c) In a tape worm note: 



1. The scolex with a circlet of hooks and suckers. 



2. The body of proglottides. Note the form of a proglottis in 

 different regions of the body. 



