200 J. D. Dana on Zoophytes. 
On coming to maturity the ova develop their young, either at 
the time of leaving the vesicle or soon after, and the vesicle be-. 
coming vacated, drops off. The young soon plant themselves 
upon some support and bud and branch, and soon become a grove 
of corallines. According to van Beneden the Campanularidee when 
first developed are like minute Meduse in shape, and have eight © | 
eyes, which are lost as the animal attaches itself.* Sir J. G. 
Dalyell, who had previously observed their forms, states that the 
young, after the tentacles are formed, enjoys the faculty of pro- 
gression by means of the inverted tentacula, as on so many feet, 
apparently to select a site; when again resuming the natural 
direction with the extremities upward, the lower surface sca 
itself below and roots there forever.t+ 
22. Buds.—Buds in the Hydras fall off after coming to maturi- 
ty ; but occasionally they give out successive shoots till small com- 
pound groups are formed, though ultimately becoming each an in- 
dependent animal. In the Sertularie and most other species, the’ 
buds are persistent. In some instances, before the zoophyte 
reached its limits in size, the number of polyps constituting it 
becomes immensely leg In a single specimen of Plumula- ~ 
ria (P. angulosa), collected by the writer in the Hast Indies, 
there are about twelve thousand polyps to — 
each plumose branch ; and, as the whole Bait 
‘Fig. Op arte ae 10. 
Ty . 
phyte, three feet long, bears these plumes, on 
and produecd by successive buddings. 
, the development of the bud, there is at first @ 
"protuberance in which the chyléid fluids gain 
access, and either move by vibration or have 
a kind of cireulation up along the sides’and 
down the axis; after a while the calicle forms, 
the polyp eaesids its arms and begins its con- 
tributions to the body-coralline. The an- 
rp hee In hen 9 the cells are m2 
os,  Pthiindisie’tet lew amples, Brus , 1044 : 
ee a: Lawes Sage 
sh a mtr 
my i 
fo. an it AVIA, aveny half inch, on ape sds, “ 
te xa ao all the offspring of a single germ, 
In 7 
nexed figures represent different results of — 
