30 CORALS AND CORAL ISLANDS. 



the base, when it is called lateral ; or (3) at the upper margin 

 outside of the tentacles, when it is called marginal ox superior ; 

 or (4) from the disk inside of the tentacles. 



Sometimes a shoot grows out from one point only of the 

 base of a polyp, like the stolon iferous stem from a strawberry 

 plant, and at short intervals gives off biids ; and thus makes a 

 linear zoophyte with a row above of flower-animals. In other 

 cases, the base spreads in all directions and buds at the edge, 

 or in the upper surface near the ^^g^., and so makes an in- 

 crusting plate consisting of a multitude of polyps. 



If the germ polyp, or that from which the compound 

 zoophyte proceeds, has the property of growing upward be- 

 yond the adult height — which the existence of coral renders a 

 possibility, and even to an indefinite degree — various otlier 

 forms may result. 



Sometimes the first polyp gives out buds from its sides, and 

 continues so to do when it grows upward ; and thus a rising 

 stem is formed with one parent polyp at the extremity of the 

 stem, and a terminal corallet to the corallum, or to each branch 

 of it. This is the case in the genus Madrepora, a species of 

 which is represented on the preceding page. Each branch in 

 the living state had at its extremity the parent polyp of the 

 branch, or that whose budding made the other polyps of the 

 branch. In such species, a new lateral branch is commenced 

 by one, among the many polyps over the surface of a branch, 

 beginning to grow and bud. Thus branch after branch is 

 added, and the little tree produced. 



Another kind of coral, growing and budding in the same 

 manner, is represented on page 31. It is a species of Dendro- 

 phyllia, from the Feejees — a genus often representing tree-like 

 forms, as the name implies. 



In other cases, budding goes on until a cluster of some size 

 is formed, and then the older or marginal polyps of the cluster 

 cease budding while the rest continue the process ; in this 

 way a stem rises, with the budding cluster of polyps at its 

 summit, and the more aged, or non-budding polyps, about its 

 sides ; and the breadth of the stem depends on the size of 



