68 



ESSAY ON SPONGES. 



the qualities of marine plants, such as roots 

 stem, branches, and vesicles bearing the young 

 in embryo, like seeds, (as exemplified in Sertularia^) 

 are formed for the support of an animal of a most 

 compHcated nature. These coverings, or moye 

 imperishable parts of zoophytal animals, gro\y in 

 the same manner, and some perhaps draw in nou- 

 xishment in a similar way, as fuci and confervce. 

 Like shells, however, they are constituent parts of 

 an integral animal, expanding with it according 

 to the laws of nature. 



The subjects in Zoophyte, as in Testacea, when 

 examined in the cabinet only, exhibit that part of 

 the animal which is the least perishable ; and of 

 course, that, by which science has been best able 

 to define, and reduce them to system, for the 

 better ascertaining the distinction of the numerous 

 species. 



It is not, however, my intention to enter into a 

 general history of the nature of zoophytes in this 

 place ; nor is it required ; since nothing further is 

 necessary for those who demand instruction in 

 this abstruse science, than to peruse the works of 

 our countryman Ellis. There are indeed some 

 of the subjects which belong to this class of be- 

 ings, that possess so small a share of apparent vi- 

 tality, and are so indefinite in shape, that even 



* Radical tubes, or ramifications resembling roots, by which 

 they are affixed to other bodies. 



