XV.] 



CORAL LAND. 



251 



the development of the bones of a man does with his 

 eating and drinking. 



Sooner or later, the coral polype dies ; then, the feelers, 

 inner sac, and all the soft upper parts of the body, and 

 those which cover the skeleton, decay, and are washed away, 

 while the skeleton, or corallum, as it is called, is left as a 

 contribution to the solid floor of the sea (Fig. 72). 



Such solitary coral polypes as have been described give 



Fig. 71. — Diagrammatic secticn of a single cup-coral, to shew the general structure 

 of the polype, and the relation of the skelettn to the soft parts. 



rt, mouth ; b, inner sac or stomach ; a', its inner opening ; c, the soft outer wall of 

 the body ; rf, the interspace between the inner sac and the bcdy-wall, with its 

 partitions ; e, the tentacles ; f, the calcified body-wall or cup of the coral ; g, the 

 hard partition of the coral ; h, the base by which the coral is fixed. 



rise to numerous eggs, the young developed from which 

 float away, and sooner or later, fixing themselves, take on 

 the form of the parent. Very often they have other modes 

 of multiplication. A coral polype may give off" small 

 buds, each of which grows into a perfect animal with its 

 own stomach, mouth, and feelers, but remains closely con- 

 nected with the parent. In ether cases, the coral animal 

 spontaneously splits into two halves ; and these, in turn, may 



