190 J.D. Dana on Zoophytes. 
These higher polyps, though similar im many respects, are thus 
distinct from others in having a set of organs growing from the 
walls of the visceral cavity devoted to the function of germina- 
tion instead of this function residing in the walls themselves; — 
and they illustrate the first step in the system of localization,— 
the distributing of different processes in the animal economy to 
distinct organs—by which the higher animals differ from the 
lower. ‘The ova in the one case grow outward from the sides of 
the polyp, escaping laterally by simple pullulation: in the other, 
they form at the margin of the ovarian lamelle, within the vis- . 
ceral cavity, and escape by passing up through the stomach and 
mouth. | sent 
12. It is perceived that the mysterious ‘polyp i is a very” <nk 
kind of organism, and we thus far detect no evidence of a veg- 
etable nature. We observe that while the plant extends its roots 
and absorbs nutriment from the soil, or:atmosphere, the polyp 
obtains its nutrition, like other animals, from food in a stomach ; 
“in the process of digestion, assi ation, as well as the 
action of the circulating: fluid on air, they are i. toto, animal. 
13. Yet we are struck with the points of external ~sabaleael 
—the flower-shaped disk—the circle of tentacles corresponding 
‘to the petals of the flower—and the series of germinal lamellz or 
dissepiments in the higher grades, situated. within, like the sta 
mens, and pistils or carpels of the flower: - 
This resemblance is rendered more striking by a fe of 
budding, on which the compound structure of zoophytes de- 
pends, as it is singularly like the production of buds.in a-plant. 
_ As seen externally, the bud in many. instances appears first asa 
slight swelling on the side of a polyp: it enlarges, and after a 
‘while a new polyp gradually grows out, with tentacles -and. vis- 
ceral cavity complete: it usually remains thus united to the pal- 
ent for life, though sometimes becoming dejached and sw imming 
off free. Comparing-it with the growing plant-bud, we find nt. 
essential difference in the process, though in one case the result 
‘is an animal, and in the other a flower or: branch of leaves. 
The new polyp at first communicates. internally with the pa- 
rent by its visceral cavity as well as the tissues of its sides, and of- 
ten this intimate connection continues after becoming, adult. 
s process, as is poke. may go on without limit; 
e out ¢ d and all, may add to the oe 
