1 68 HIDDEN BEAUTIES OF NATURE 



of Devonshire, with this advantage, that it has power 

 to secrete a coral skeleton a power, however, that is 

 quite involuntary. This property of secreting a hard 

 calcareous skeleton is not a building process, any 

 more than our skeletons are voluntarily built by us. 

 Different kinds of polyps secrete different kinds and 

 patterns of corals. The polyps which secrete fungi- 

 form coral could not secrete the branched madrepore, 

 neither can the madrepore polyp produce organ-pipe 

 coral. The radiate structure of ordinary corals is but 

 the expression of the internally radiate structure of 

 the polyp. When alive, the top and usually the sides 

 of the coral are concealed by the outer skin of the 

 polyp, including above the disc and tentacles, and 

 into the depression or calicle at the top. The polyps 

 are able to elevate their crowns above their coral discs, 

 and to spread out their tentacles or feelers, and to 

 retreat again to the interstices or cells, as the case 

 may be. 



The creature sends out a bud similar to the hydra 

 of our ponds, a mouth appears in the bud, feelers 

 next appear, the bud then enlarges to the size of its 

 parent. 



In the case of hydra, the bud at this stage severs 

 its connection and becomes a free and independent 

 creature. Not so with the coral bud. It seems to 

 realize that * union is strength,' for it remains, and 

 similar buds are formed, so that as the budding 

 process continues, a compound group is the result ; 

 and still the buds are added to the living colony until 



