Natural History of British Zoophytes. 445 



it there displays its organs, and begins the capture of its prey ;* for, 

 unlike higher organisms, the polype is at this the period of its birth 

 as large and as perfect as it ever is at any subsequent period, the 

 walls of the cell having become indurated and unyielding, and set- 

 ting a limit to any further increase in bulk. The growth being 

 thus hindered in that direction, the pulp, incessantly increased by 

 new additions of nutriment from the polype, is constrained and 

 forced into its original direction, so that the extremities of the cell 

 or tube, which have remained soft and pliant, are pushed onwards, 

 the downward shoot becoming a root-like fibre, and the upper con- 

 tinuing?the polypidom, and swelling out as before, at stated inter- 

 vals, into cells for the new developement of other polypes ; and just 

 as the fleshy substance extends in either direction, upwards or ho- 

 rizontally, it exudes from its surface " a liquid albuminous matter, 

 — at first soft and transparent, but which after a short time becomes 

 consolidated, and, in proportion to the time it remains, becomes more 

 and more dense." The polypidom then, however like unto certain 

 vegetables in appearance, has, as Ellis said, nothing vegetable about 

 it, but is entirely an animal production, and excreted by the ani- 

 mated pulp which fills its whole interior. Ellis and his followers 

 are only so far wrong, that they have attributed to the polypes 

 themselves what is actually due to the pulp, whether medullary or 

 cortical. The latter is that from which the polypidom is exuded ; 

 for, indeed, the cell or crust always precedes the existence of the 

 polypus which is developed within it, while the polypidom is de- 

 veloped from the gelatinous substance of the reproductive gemmules 

 before any polypes begin to be formed, and it continues to be de- 

 veloped and extended by the fleshy mass of the zoophyte, whether 

 polypes are developed in the cells or not. " There is but one life, 

 and one plan of developement, in the whole mass ; and this depends 

 not on the polypi, which are but secondary and often deciduous parts, 

 but on the general fleshy substance of the body." t 



* " The cell," says Lamouroux, speaking of the Flustra, " is yet closed, but 

 through the transparent membrane that covers its surface, the movements of a 

 polypus may be perceived, who delays not to burst the enclosure of his little 

 habitation ; then, exulting in the plenitude of existence, he exercises its func- 

 tions, and by the assistance of twelve tentacula that surround his mouth, he gives 

 a rotatory motion to the water, and involves in this diminutive whirlpool the 

 animals on which he feeds. 1 ' — Corall, p. 48. 



f Grant's Outlines of Comp. Anatomy, p. 14 — We take the opportunity of 

 recommending this valuable work to every student of natural history. 



