56 THE POLYPI. $$ 51, 52. 
§ 51. 
TIL. There are Polyp-colonies which contain two kinds of individuals, 
those which are sexless, and those having sexual organs only at certain 
epochs, These last are campanulate or medusoid, and their sexual organs 
are developed in various parts of their body. 
In Coryne ® and Syncoryne,® the eggs appear upon the external sur- 
face of the stomach, then fall into the cavity of the mantle, through the 
openings on the border of which they escape into the water. In the medu- 
soid individuals of Coryne fritidlaria and Corymorpha nutans, the sexual 
organs appear to be formed in the angles of the borders of the disc, and 
in Campanularia in the disc itself. * 
§ 52. 
As to the embryonic developments of Polyps, it is probable that in a 
great number (perhaps all) there is a metamorphosis. 
The development commences by the usual segmentation of the vitel- 
lus,” by which it is ultimately converted into an ovoid, contractile body ; 
this turns upon its longitudinal axis by means of cilia, with which it is en- 
tirely covered, swimming about like many. Infusoria. These embryos, 
otten developed in the mother, have sometimes been taken for swimming 
eggs.” Afterwards they attach themselves to some body, and usually lose 
their cilia; the free extremity of their body opens, allowing the escape of 
the Polyp, which, in the mean while, has been developed in the interior, 
with its arms in front. 
Many of the Polyps thus produced multiply by 
gemmation, and thus become the foundation of new Polyp-colonies. 
1 Wagner (Isis 1833, Taf. XI. fig. 8). 
2 Loven (Wiegmann’s Archiv. 1837, I. Taf. 
VI. fig. 19, 20). 
8 Steenstrup, Ueber d. Generationswechsel, p. 
23, 24. 
1 It is indeed singular that with Hydra the divi- 
sion of the vitellus takes place before the eggs are 
either detached from the body, or are surrounded 
by a dentated envelope. I do not yet know at what 
epoch the development of the embryo commences, 
for I have never seen the young come forth. It is 
impossible for me to say whether or not these 
Polyps experience a metamorphosis. Pallas (Ka- 
rakteristik d. Thierpflanzen p. 53) has seen the 
young Polyps come forth from the egg, but he gives 
no description. Laurent, also, only says that the 
young animal escapes formed from the egg, with- 
out describing the embryo (Froriep’s neue Notizen, 
No. 513, pl. 101). The segmentation of the vitellus 
has been observed. hy Van Beneden in the eggs of 
Pedicellina. See his Rech. sur V’anat. d. Bryo- 
zoaires (suite) loc. cit. XLX. p. 18, pl. IL. 
2 As would be inferred from his description, Cav- 
olini (loc. oit. p. 47, 50, Taf. IV. fig. 7-10 and 13- 
15) has observed similar embryos to those of Gor- 
gonia and Madrepora. His descriptions of various 
eggs of Sertularia leave no doubt that they also 
snake the matter any more clear ; for, even admit- 
ding that they are proper ova, it is difficult to con- 
¢eive how the impregnation (of which the segment- 
ation for a definite result is the sequela) could take 
place while the ova are thus buried in the capsul 
were embryos (Ibid. p. 56, 80 et seq.). Grant also 
has taken for eggs the contractile, ovoid embryos 
of Lobularia digitata, which he has seen issue 
from the mouth of this animal (Froriep’s Notizen 
1828, No, 440, p. 340). Meyen has well described 
and figured the ciliated epithelium of those of Al- 
cyonella stagnorum (Isis 1828, p. 1228, Taf. 
XIV. fig. 4, 5). Loven has observed the elon- 
gated embryos of Campanularia geniculata, and 
has taken the division of the vitellus for a sponta- 
neous fissuration of the embryos (Wiegmann’s 
Archiy. 1837, I. p. 260, Taf VI. fig. 13,14). Ac- 
cording to Rathké, who has seen movable lenticu- 
lar embryos in the stomachs of Actinia, these 
polyps experience a metamorphosis (Reise Be- 
merk. aus Taurien zur Morph. p. 10, Taf. 1, fig. 
12). 
y This metamorphosis has already ‘been observed 
by Cavolini (loc. cit. p. 261, Taf. VI. fig. 7) with 
Sertularia racemosa, and more lately by Lowén 
(loc. cit. p. 261, Taf. VI. fig. 15-17) with Campa- 
nularia geniculata, There are always developed 
in the interior of the embryos of Alcyonella stag- 
norum. two Polyps, even before the first have es- 
caped from the egg ; when the escaped embryo has 
become fixed, its skin bursts, and the Polyps escape 
but are able to return again as into a mouth 
116, and Hancock, Ann. Nat. Hist. 1850, V. p. 
282.— Ep. 
* (End of § 51.] See Schultze (Miller’s Arch. 
1850, p. 57), who has found with Campanularia 
The subject requires further research. See also 
Steenstrup, Untersuch. iib. Hermaphroditismus, p. 
1 capsules corresponding to those for egg- 
capsules pointed out by Loven (loc. cit.).— Ep. 
