CORAL-MAKING POLYPS. 23 
Cerianthus of the Philippine Islands, with its thread-cells, 
builds a sheath or leathery tube one foot four inches in 
length, that is sunk into the mud. 
Development.—Anemones multiply by budding, or, if 
pieces of the disk are cut or torn off, they will grow into 
anemones. They also deposit eggs, the young being at 
first free swimmers, by means of cilia, finally becoming 
fixed upon the bottom, and assuming the adult form. 
Note.—In their habits they are remarkable. One observed by 
Dr. Collingwood in the China Sea was two feet in diameter, giving 
shelter in its stomach to a little fish, that, when danger approached, 
rushed into its: protector, whose tentacles closed up like a door. A 
fish, known as Premnas biaculeatus, also lives within the stomach of 
the anemone, Actinia crassicornis. Some live a roving life, like the 
Adamsia, that is often found upon the back of the hermit-crab, that, 
upon leaving its shell, obliges its friend, the anemone, to change also. 
The Urticina is luminous. 
VaLuE.—The anemones are great purifiers, and are eaten in vari- 
ous parts of the world. 
Coral-making Polyps.—The coral animal may be 
considered an anemone that has the power of secreting 
lime. In the star-coral (Astrea), the young is seen at the 
end of June—a little oblong-shaped body, swimming about 
by its cilia, or oars. It soon attaches itself to the bottom, 
and, if in a few days it should be removed, there would 
be found a little platform with radiating partitions of lime 
alternating with the soft ones that we have seen in the 
anemone. If allowed to grow, tentacles soon appear ; 
other small partitions are now secreted, that extend to 
the outer wall, which is also being secreted ; and, finally, 
we have a coral polyp, from which others branch, until 
large blocks are formed of many individuals, but all con- 
nected. So it will be seen that the polyp is not an insect, 
neither does it erect or build its house any more than a 
man builds his skeleton, but is a lime-secreting animal, 
pure and simple. 
