ZOOLOGY. 341 



that reefs of rocks can be due in any way to " animalcules," talk of 

 electrical forces, the first and last appeal of ignorance. Others call in 

 the fishes of the seas, suggesting that they are the masons, and work 

 with their teeth in the accumulation of the calcareous material. Very 

 many of those who discourse quite learnedly on zoophytes and reefs, 

 imagine that the polyps are mechanical workers, heaping up these 

 piles of rock by their united labors ; and science still retains such 

 terms as polypary, polypidom, as if each coral were the constructed 

 hive or house of a swarm of polyps, like the honeycomb of the bee, 

 or the hillock of a colony of ants. 



It is not more surprising, nor a matter of more difficult comprehen- 

 sion, that the polyp should form coral, than that the quadruped should 

 form its bones, or the mollusc its shell. The processes are similar, 

 and so the result : in each case it is a simple animal secretion, a 

 formation of stony matter from the aliment which the animal receives, 

 produced by certain parts of the animal fitted for this secreting pro- 

 cess. This power of secretion is the first and most common of those 

 that belong to living tissues ; and, though differing in different organs 

 according to their end or function, it is all one process, both in nature 

 or cause, whether in the animalcule or in man. Coral is never, there- 

 fore, an agglutination of grains made by the handiwork of the many- 

 armed polyps ; for it is no more an act of labor than bone-making in 

 ourselves. And, again, it is not a collection of cells into which the 

 coral animals may withdraw for concealment, any more than the 

 skeleton of a dog is its house or cell ; for every part of the coral of a 

 polyp in most reef-making species is enclosed within the polyp, where 

 it was formed by the secreting process. It is important that this point 

 should be thoroughly understood, and fully appreciated. 



The reproduction of coral by buds is a process so similar to the 

 production of buds in vegetation, that a remembrance of the latter 

 will aid much in conceiving of it. The bud generally commences as a 

 slight prominence on the side of the parent ; the prominence enlarges, 

 and soon a circle of tentacles grows out, with a mouth at the centre ; 

 enlargement goes on, till the young finally equals the parent in size. 

 Thus, by budding, a compound group is commenced ; and it is evident 

 that if the parent and the new polyp go on budding again, and so on, 

 the compound group may continue to enlarge. This is the fact in 

 nature. The polyps, one and all, continue propagating by buds, until 

 in some instances thousands, or hundreds of thousands, have pro- 

 ceeded from a single one, and the colony has spread to a large size. 

 Such is the Madrepora and Astraea. There are modifications of this 

 process, analogous to those in vegetation, but we need not dwell upon 

 them in this place. 



It is obvious that the connection of the polyps in such a compound 

 group must be of the most intimate kind. The several polyps have 

 separate mouths and tentacles, and separate stomachs ; but beyond 

 this there is no individual property. They coalesce, or are one, by 

 intervening tissues, and there is a free circulation of fluids through 

 the many pores or lacunes. The zoophyte is like a living sheet of 

 animal matter, fed and nourished by numerous mouths and as many 

 i 29* 



