Natural History. 415 



row of polypi around the smooth fleshy centre. Breadth seems 

 diminished in proportion to the length of a specimen. 



Thus it appears that the most luxuriant zoophyte — one composed 

 of a thousand animals — originates by a single polypus only ; and 

 that the earliest recognition of its elements is as a circular spot or 

 spherical segment. 



Awaiting some future opportunity of illustrating the mode of in- 

 crement peculiar to zoophytes, I shall only observe that, in the first 

 stage of the Sertularia polyzonias, for example, a single enlarge- 

 ment forms the summit of the stalk. It is invested by a delicate 

 membrane, which, instead of including a solitary head, covers a 

 twin bud also. As the former increases, the latter forks off from 

 it ; next another from that which is the more mature, and thus with 

 the rest. The increment of the Tubularia ensues only during the 

 subsistence of the head. But the head is deciduous, falling in ge- 

 neral soon after recovery from the sea. It is regenerated at inter- 

 vals of fi'om ten days to several weeks, but with the number of ex- 

 ternal organs successively diminishing, though the stem is always 

 elongated. It seems to rise within this tubular stem from below, 

 and to be dependent on the presence of the internal tenacious mat- 

 ter with which the tube is occupied. A head springs from the re- 

 maining stem, cut over very near the root ; and a redundance of 

 heads may be obtained from artificial sections, apparently beyond 

 the ordinary provisions of natm*e. Thus 22 heads were produced 

 through the course of 530 days, from three sections of a single stem. 

 The reproductive powers of some animals are very great. It would 

 be worthy of investigation whether, in some of the Annuhsa^ as 

 they are now denominated, the whole elements of the entire ani- 

 mal do not reside in each segment. Fragments from the lower ex- 

 tremity of the largest specimens I could procure of the Amphiirite 

 VentilabrufHy and others of that genus, have regenerated both the 

 complex and beautiful plume, forming the branchiae before and the 

 secretory glands behind, as they may be conjectured, affording the 

 glutinous matter for fabricating the tube. But neither can the sin- 

 gidar niec/ianical properties of the former be used, nor do the lat- 

 ter seem of any avail under the artificial state of the redintegrated 

 fragment. 



All the preceding results, together with many others alike sin- 

 gular, are illustrated by drawings from the pencil of skilful artists. 



K e 2 



