30 
ZOOLOGY. 
covering of the animals which ma}^ be swallowed by the Actinia are 
rejected from the mouth after the soft parts are digested. 
Sea-anemones have been found to have a slight sense of 
smell. Nearly all sea-anemones, besides arising from eggs, 
increase by budding, new individuals arising at or near the 
base of the large one. 
The coral polyps only differ from the sea-anemones in 
secreting a limestone sui)port or coral-stock. Corals are 
either cup-shaped and single, or are compound, forming 
Fig. 31.— Coral polyp {Astroides calycularis) expanded. From Liitken's 
Zoology. 
branching or rounded masses. The soft parts are supported 
by limestone partitions secreted in the chambers of the 
polyp. 
All Actinozoans develop from eggs, and at first appear 
as little oval, ciliated, free-swimming embryos {gastrulce), 
which eventually become attached to the bottom of the 
sea. 
Before the embryo becomes fixed and the tentacles arise, 
the lime destined to form the partitions begins to be de- 
