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." Corall, p. 43. 
f Grant's Outlines of Comp. Anatomy, p. 14 We take the opportunity of 
recommending this valuable work to every student of natural history. 
