21 



Polypcellerne ere runde, staa temmelig tæt, uden at 

 være sammenvoxede og have paa deres Rand, naar Poly- 

 pen enten ikke er fuldt udstrakt eller paa det nærmeste 

 indtrukken. 8 Papiller; er Polypen ganske udstrakt, gaar 

 dennes Bagkrop over i Cellen, uden at Overgangen er 

 synderlig mærkbar. Tab. XVIII, Fig. 1. 



Polyperne ere omtrent 8""" lange, cylindriske, med en 

 temmelig udpræget Bagkrop, der er forsynet med 8 Ribber, 

 dannet af paatversliggende Spilder, hvilke fortsættes et 

 Stykke nedad, paa Cellen og opad paa Forkroppen, hvor 

 de lobe sammen og forme sig i Guirlander, som gaa over 

 paa Tentaklerne, Tal). XVIII, Fig. 1. Op imod Mund- 

 skiven sees imellem Tentaklernes Grunddel triangulære, 

 nogne Rum. i hvis Midte lober en Række Spikler over 

 paa Mundskiven, Tab. XVIII, Fig. 1. Tentaklerne ere 

 omtrent halvt saa lange som Kroppen og have en rig 

 Spikelbekhedning paa deres aborale Flade. Pinnulerne 

 staa temmelig tæt, ere lange og forsynede med Spikler, 

 Tab. XVIII, Fig. 1. 



Anatomisk-histologisk Undersøgelse. 



Hele Zoanthodeinet er udvendigt beklædt med et 

 Ectoderm, der dannes af flere Lag polyædriske Celler, ikke 

 synderligt afvigende fra dem, der tidligere ere beskrevne; 

 men i dette Ectoderm, ligesom i det indenfor liggende 

 hyaline Bindevævslag, ere Spiklerne leirede. Ogsaa her 

 viser det sig, at hvor Spiklerne ligge i Bindevævet, der 

 ere de omgivne af Ectodermceller. Paa Polyperne er den 

 ydre Epithelialbeklædning noget tyndere end paa Stammen 

 og Grenene, hvilket gjor, at Polyperne ere mere gjennem- 

 sigtige end de øvrige Dele. 



Svælget er langt, cylindrisk og forsynet med b' enkle 

 Spikelrækker, hvoraf tre ligge paa hver Side med et bredt, 

 nøgent Rum paa Bug- og Rygsiden, Tab. XVIII, Fig. 

 2. 3. Svælgrenden er oval og beklædt med lange Pidske- 

 celler, som sædvanligt. 



I den bagre Del af Mavehulheden og tildels i dens 

 Forlængelse i Grenen sees Æg i forskjellige Udviklings- 

 stadier. Hos den unge Polyp, omtrent 4""" lang, der nylig 

 havde forladt sit embryonale Liv og sat sig fast paa det 

 omtalte Ror, kan det bedst sees, hvorledes Polypens Bag- 

 krop egentlig danner Polypcellen; thi her er endnu ingen 

 Stamme eller Gren dannet, — det er kun Polypkroppen, 

 som her fremstiller sig, og dennes forreste Del har trukket 

 sig noget ind i dens bagre, der former sig som Celle, Tab. 

 XVII, Fig. 55, b. 



The polyp-cells are cylindrical, and are pretty closely 

 placed to each other without. however, being concreted 

 together ; on their margin they have — when the polyp is 

 either not fully extended, or when it is almost entirely 

 retracted — 8 papillæ. When the polyp is quite extended. 

 its posterior body passes over into the cell without the 

 transition being particularly apparent, (Pl. XVIII, fig. 1.) 



The polyps measure about 8'"'" in length; they are 

 cylindrical, and have a rather prominent posterior body 

 furnished with 8 ribs formed of transversally placed spi- 

 ddes which are produced a little way down the cell, 

 and on to the anterior body. upwards, where they unite 

 together, forming tbemselves into garlands that pass over 

 to the tentacles (Pl. XVIII, fig. 1.) Up towards the 

 oral disk, between the basal parts of the tentacles, triang- 

 ular bare spaces are seen, in whose middle. a series of 

 spicules passes over to the oral disk (Pl. XVIII, fig. 1.) 

 The tentacles are about half the length of the body, and 

 have a rich spicular covering on their aboral surface. 

 The pinnules are placed pretty closely to each other, 

 and are long and furnished with spicules (Pl. XVIII, fig. 1.) 



Anatomo-histological Examination. 



The entire Zoanthodem is, externally, covered with 

 an ectoderm formed of several lavers of polyhedrical cells 

 not materially differing from those which have, previously, 

 been described, but in this ectoderm, as also in the 

 hyaline connective-tissue lying inside of it, the spicules 

 are entrenched. Here, also, it appears that where the 

 spicules lie in the connective-tissue, they are surrounded 

 by ectoderm cells. The external epithelial covering is 

 somewhat thinner on the polyps than on the stem and the 

 branches, which causes the polyps to be more transparent 

 than the other parts. 



The gullet is long and cylindrical, and is furnished 

 with 6 single series of spicules, of which 3 are situated 

 on each side, leaving a broad, bare, space on the ventral 

 and- dorsal side, (Pl. XVIII, fig. 2. 3). The gullet pas- 

 sage is oval, and is covered with long tiagelliform cells as 

 usual. 



In the posterior portion of the gastral cavity and, 

 also, partly, in its prolongation into the branch, ova in 

 different stages of development are seen. In the young 

 polyp — about 4'""' in length — which had lately emerged 

 from the embryonal existence and attached itself to the 

 tube already mentioned, it can best be observed how the 

 posterior body of the polyp, in reality, forms the polyp- 

 cell, because there is. here, no stem or branch vet formed ; 

 it is the polyp-body that alone presents itself, here, and 

 its anterior part has retracted itself somewhat into its 



