36 James D. Dana, Esq., on the Structure, 



II'. Structure, Growth, and Habits of Coral Zoophytes. 



1. Structure and Growth of Zoophytes. 



A singular degree of obscurity has been thrown around the 

 growth of coral zoophytes and coral formations, through the 

 various speculations which have been offered in place of 

 facts ; and to the present day, the subject is seldom men- 

 tioned without the qualifying adjective mysterious expressed 

 or understood. Some writers, scouting the idea that reefs 

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

 electrical forces, the first and the 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 accumula- 

 tion 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 labours ; and science still re- 

 tains 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 vain to hope to understand fully the works of Him 

 who is himself infinite and incomprehensible. The scrutiniz- 

 ing eye of science penetrates with far-reaching sight the 

 system of things about us, and in the dim limits of vision 

 reads everywhere the word mystery. All life, animal and 

 vegetable, and all that is inanimate, declare it ; surely there 

 is no special reason, except such as may arise from want of 

 study and consideration, for attributing it pre-eminently to 

 the humblest grades of existence. 



It is not more surprising nor a matter of more difficult 

 comprehension 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 process. 

 This power of secretion is the first and most common of 



