14 / J. D. Dana on Zoophytes. 
indefinite increase; and as this prolate growth is connected with 
budding, it often produces large foliate zoophytes. 
51. The process of consentaneous growth and death is one of 
the most important in the history of zoophytes, for upon it de- 
pend the size they attain and their great geological interest. An 
example of it is illustrated in figure 3 » representing a Caro- 
phylla, the whole of which is lifeless coral excepting the polyp 
tipping each branch. The bud after development continues 
elongating its branch, and when but a line long, it dies at base, 
and so the polyp continues dying as it grows above. It is evident 
consequently, the tissues dry up in thé old corallum 
a 
_ 52. In some Cyathophyllide this process of death goes on 
interruptedly, as explained by Ehrenberg. The tissues of the 
' oes OO crease 
filling the cellules; the corallum consequently becomes covered 
with encircling ridges, or appears as if formed of a series of 
inverted cones. In some cases 
the genus Strombodes, the living portion becomes. retracted at 
intervals to the very centre, all the rest dying, and afterwards 
the animal grows again and spreads to its original diameter ; 
tion which often follows reproduction) cannot properly be 
sidered a generic distinction. In the Cyathophylla there are all 
Varieties, from the very roughly wrinkled species to those which 
are smooth. ‘There are also corals identical in structure with the 
Strombodes, which present nothing of it; and the same speci- 
The facts stated in the preceding volume, page 201, respecting 
