CORAL 7 OOP H Y TES. 87 
coral productions of the sea, there are other forms of life which replace 
the dying polyp. The process of wear is thus entirely prevented. 
The older polyps, before death, often increase their coral secretions 
within, filling the pores occupied by the tissues, and rendering the 
corallum more solid; and this is another means by which the trees of 
coral growth, though of slender form, are increased in strength and 
endurance. 
The facility with which polyps repair a wound, aids in earrying 
forward the results above described. The breaking of a branch is no 
serious injury to a zoophyte. There is often some degree of sensibility 
apparent throughout a clump, even when of considerable size, and the 
shock, therefore, may occasion the polyps to close. But in an hour, 
or perhaps much less time, their tentacles will have again expanded; 
and such as were torn by the fracture will be in the process of com- 
plete restoration to their former size and powers. ‘The fragment 
broken off, dropping in a favourable place, would become the germ of 
another coral plant, its base cementing by means of coral-secretions 
to the rock on which it might rest; or if still in contact with any part 
of the parent tree, it would be reunited and continue to grow as before. 
The coral zoophyte, may be levelled by transported masses swept over 
by the waves; yet like the trodden sod, it sprouts again, and continues 
to grow and flourish as before. The sod, however, has roots which 
are still unhurt; while the zoophyte, which may be dead at base, has 
a root—a source or centre of life—in every polyp that blossoms over 
its surface. Hach animal might live and grow if separated from the 
rest, and would ultimately produce a mature zoophyte. 
We close this review of the characters of coral animals, which is a 
mere abstract of the fuller descriptions in the General Report on 
Zoophytes, by alluding briefly to one division of the Actinoidea, not 
yet touched upon, and also to the Hydroidea and Bryozoa, which are 
likewise coral-making animals. 
Tue ALCYONACEA. 
The polyps of the group among the Actinoidea, here referred to, 
differ from those which have been occupying us, in having but eight 
tentacles, and these are fringed with minute papille. The organ-pipe 
coral (Tubipora) is of this kind. When expanded in the sea, a clump 
resembles a bed of pinks, or looks like a lilac-cluster that had been 
dropped in the water; and this resemblance extends to colour and 
size as well as form. 
Some of these zoophytes secrete lime and form a tube; and of this 
