POLYPES. 
339 
all the other parts of the body ; but the reporter must definitely assert, 
that it does form an ovary at certain seasons, in the same way that the 
testes are developed from that part of the body which is situated 
between the origin of the tentacula and the foot, which Laurent con- 
siders as pustules, and which, according to his opinion, must originate 
from a faulty construction of the medium surrounding the polypi, which 
the reporter cannot assent to, as he observed the testes, with their living 
spermatozoa, not only in those Hydrce which he kept, but also in those 
which he had collected from fresh water, 
Ehrenberg saw both sexes united in the Hydra viridis, but he also 
remarked individuals, that possessed male or female organs only (Fror. 
N. Notiz. Bd. 22, p. 58). He could not discover any urticating qualities 
in the Hydra (Arch. 1842, i. p. 72), and therefore thinks, that the fang- 
hooks and poison pustules of the Hydrce cannot be called stinging- 
organs. Erdl corrects Ehrenberg’s description of the hook-organs of 
Hydra in this respect (Mull. Arch. 1841, p. 429), that it is not the 
round part of the organ which first proceeds from a wart of the fang- 
arm, but always the thread, then the neck with the spines, and lastly, 
the round part ; and this the reporter can fully confirm. According to 
his observation, the Hydrce fling these threads with the poison pustules 
towards the animals, which they seize and remain fixed to ; they also 
hang abundantly on the arms of the Hydrce themselves, by which the 
poison bladder floats in the water. Ehrenberg has been deceived by 
this, and erroneously assumed, that the poison bladder first comes from 
the arms; for this reason, the Hydrce could not, with these organs, 
which cannot at all be properly called hooked-organs, lay hold of any 
animal; and they are much more correctly defined by the name of 
poison organs, since they have an active poisonous effect on small 
insects, Crustacea and Annelides, which die so soon as they are only 
touched by a pair of these organs. The bristle-shaped short threads, 
which project from the small oval corpuscles found by Corda, are used 
by the Hydrce for holding their prey (Ann, d. Sc. Nat. t. viii. pi. 18, 
fig. 5). 
Hassall has described, under the name Echinochorium, a polype 
allied to Coryne (Ann. Nat, Hist. vol. vii. p. 371). The polypidom is 
encrusting ; surface raised into numerous rough papillas ; polypi hydroid, 
naked, pedicellated. They have, in the only species, Echin. clavigerum, 
a clavate shape, are not retractile within cells, and are furnished with 
claviform tentacula. Another Coryne-\i\.Q genus has been discovered at 
Naples by Philippi, upon Conchylia (Arch. 1842, i. p. 37). The small 
two lines long twelve-armed polypi rest here upon a general cuticular 
expansion. 
Steenstrup has observed a new Coryne in Iceland, and has named it 
Coryne fritillaria (Uber den Generation swechsel, p. 20). It consists of 
383 
