CORAL ZOOPHYTES. g] 
therefore, an agglutination of grains made by the handiwork of the 
many-armed polyps: for it is no more an act of labour than bone- 
making in ourselves. And again, itis not a collection of cells into 
which the coral animals may withdraw for concealment, any more 
than the skeleton of a dog is its house or cell: for every part of the 
coral of a polyp in most reef-making species is enclosed mthin the 
polyp, where it was formed by the secreting process.* 
It is important that this point should be thoroughly understood, and 
fully appreciated. ‘That error may no longer be perpetuated, the 
words polypary and the like, have been rejected by the author in the 
volume on Zoophytes, and the more familiar term coradlum has been 
used instead.t With this introductory explanation, we proceed. 
a. Structure of Coral Animals or Polyps.—A good idea of a coral polyp 
may be had from comparison with the garden aster: for the likeness 
in external form and delicacy of colouring is singularly close. The 
aster consists of a tinted disk bordered with one or more series of 
petals; and in exact analogy, the polyp-flower, in its most common 
form, has a disk often richly coloured, fringed around with petal-like 
organs called tentacles. Below the disk, in contrast with the slender 
pedicel of the plant, there is a stout cylindrical pedicel or body, often 
as broad as the disk itself, and usually not much longer, which con- 
tains the stomach and internal cavity of the polyp: and the mouth, 
which opens into the stomach, is placed at the centre of the disk. 
Here, then, the flower-animal and the garden-flower diverge in cha- 
racter, the difference being required by the different modes of nutrition 
in the two kingdoms of nature. 
There are many species of polyps, which have all the external and 
internal characters of coral polyps, yet secrete no lime or coral. Our 
descriptions of structure may be best drawn from them, and afterwards 
the single peculiarity of the coral-making polyp—its secretion of 
* It is not, perhaps, within the range of science to criticise the poet; yet we may say 
in this place, in view of the frequent use of the lines even by scientific men, that more error 
in the same compass could scarcely be found than in the part of Montgomery’s Pelican 
Island, relating to coral formations. The poetry is beautiful, the facts nearly all errors 
—if literature allows of such an incongruity. For ourselves, we think that fancy tran- 
scends its appropriate limits when false to nature. 
T See page 15, of the Report on Zoophytes. The term corallium has been set aside by 
authors because of its being used for a genus of corals. Corallum is an old form of the 
same word, as particularly explained on the page just referred to, and is not liable to this 
objection. The true nature of calcareous corals was first pointed out by Milne Edwards, 
and Ehrenberg. 
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