3482 



CCELENTERA TES 



in the illustration on p. 3480. Its pedestal is formed of a delicate network 

 with fine rays or spokes, connected in a regular manner by transverse sup- 

 ports. 



Plentiful as are the solitary corals, they are surpassed in number by those 

 which form compound stocks, that is to say, in which the buds do not fall off but 

 go on budding till coral islands and barrier reefs are built up. As it is impossible 

 to give here more than a very few illustrations of the many different ways in which 

 the coral stocks grow, we can only select a few types. In Dendrophyllia, as shown 

 in the illustration, we have a tree-like growth; each polyp secreting a solid 

 pedestal for itself, and living in a depression in the top. This is shown in the 

 section B. Into this depression the soft animal can withdraw at the approach 

 of danger, drawing all its tentacles (which also contract) down to a. The space 



A MASSIVE CORAI,, Astroides. 

 (Natural size.) 



occupied by the animal is not very roomy at the best, and it is further limited both 

 by a great columella d, rising up in its interior, and by the solid septa b projecting 

 into it all round. It must not be forgotten that these parts are not in the animal 

 but outside of it, and as they are secreted they push the skin up and never pene- 

 trate into the tissues themselves. These polyps bud at intervals, the apical polyp 

 most frequently; and the result is a simple branched stock, as seen. 



A different kind of stock is developed when the polyps produce many buds, 

 as in the madrepores. In these delicate stocks, selected polyps spring up above 

 the rest, and their sides become covered with small buds. Space would obviously 

 not permit all these small buds to bud again in the same manner. A few favored 

 ones, however, which have sufficient room next spring out and become 

 covered again with small buds. Each bud is a living, feeding, coral animal, 



