83 



en Bredde af 3 —4""". imedens de øvrige, almindelige Polyper 

 indtage paa samme Sted Lidt over 1""". Tentaklerne ere 

 sammenlimede, og deres Ender indbøiede, hvorved Adgan- 

 gen til Mundaabningen er fuldstændigt spærret. Ribberne 

 og Furerne paa den ydre Kropsvæg ere stærkt fremtrå- 

 dende, Fig. 5. Disse svangre Polyper, der siden skulle 

 nærmere omtales, gaa umiddelbart over i Grenen uden at 

 forene sig med nogen anden Polyp. 



Anatomi sk-histo!ogisk Undersøgelse. 



Stammen har en ydre Beklædning, Ectodermet, dannet 

 af flere Lag polyædriske Celler. I det indre Lag 'sees 

 imellem Ectodermcellerne flaskeformede Celler med Ijen 

 Udløber og en afiang Kjerne, omgiven af et fintkornet Indhold 

 — encellede Slimkjertler — ; desforuden er i Ectodermet 

 afleiret en Mængde Spikler, der ogsaa tindes i det inden- 

 for værende hyaline Bindevæv, men altidomgivne afEctoderm- 

 celler. 



I Bindevæ.vslaget tindes Bindevævslegemer med en 

 eller tiere Udløbere, der korrespondere med hverandre 

 samt Ernæringskanaler. Ved at undersøge de svangre 

 Polyper viser det sig, at Mundaabningen er tillukket ved 

 en slimet Masse, at Svælget er i |høi Grad udvidet, dets 

 Vægge fortykkede, Fig. (i. a, og Hulheden opfyldt af Em- 

 bryoner i forskjellige Udviklingsstadier. — dog ere de, 

 der ligge nærmest Mundspalten, videst komne, hvorfor 

 ogsaa den øverste Del af Svælget er mest udvidet. Fig. 

 6, b. I Mavehulheden sees endnu enkelte uudviklede Æg, 

 indesluttede i de stilkede Kapsler, der taue deres Udspring 

 fra Septula. 



Det er et mærkeligt Forhold, som her optræder, idet 

 Svælget virkelig omdannes til en Uterus, hvori Ungerne 

 udvikle sig. Paa flere Polyper iagttages, at den bagerste 

 Kropsdel, just der, hvor den gaar over i Grenen, er op- 

 svulmet, imedens den forreste Del endnu er normal ; men 

 Tentaklerne ere begyndte at lime sig sammen, og deres 

 Ender ere indkrængede. Naar disse Polyper aabnes, 

 tindes Æg i forskjellige Stadier, men alle indesluttede i 

 deres stilkede Kapsler, sædvanlig et Æg i hver Kapsel. 

 Svælget er ikke udvidet og er enten tomt eller indeholder 

 nogle Foraminiferer, Rester af de indtagne Fødemidler. 

 Mange af Æggene have gjennemgaaet Furingen, ere altsaa 

 befrugtede, men den egentlige Fosterdannelse er neppe 

 begyndt. Saasnart denne tager sin Begyndelse, forlader 

 Larven, endnu indesluttet i Ægget, Kapselen, og Svælget 

 er nu præpareret til at modtage Ungen, for at den der 

 kan gjennemgaa sin videre Udvikling. Mundaabningen er 

 ua nske lukket ved det omtalte Slim, saa Polypen kun kan 

 faa sin Næring igjenneni den i Gren eller Stamme forlængede 



it attains a breadth of 3- -4 whilst the rest of the 



genera] body of the polyps attain. in the same situation, 

 only a Little more than 1""" in breadth. The tentacles 

 are glued together, and their extremities are curved inwards, 

 causing the access to the oral aperture to be completely 

 closed. The ribs and the grooves on the exterior wall of 

 the body are strongly prominent (fig. 5). These fructi- 

 tied polyps, which later on shall be further discussed, pass 

 directly over linto the branch without uniting themselves 

 to anv other polyp. 



Anatomo-histological Examination. 



The stem has an exterior covering — the ectoderm 

 formed of several lavers of polyhedrical cells. In the 



i if layer. between the ectodermal cells, bottle-shaped cells 



are seen, with a prolongation, and an oblong "mulens 

 surrounded by a minute granular substance — unicellular 

 mucous ulands — there is. besides, entrenched in the 

 ectoderm, a multitude of spicules; these are also found in 

 the hyaline connective-tissue situated on its inner side. hut 

 always surrounded by ectodermal cells. 



In the connective-tissue laver, connective-tissue cor- 

 pusch's having one or more prolongations which correspond 

 with eacb other. and also nutritory ducts, are found. On 

 an examination of the fructified polyps, it is seen that 

 the oral aperture is closed by a mucous ma.ss; that the 

 gullet is, in a, high degree, dilated, its walls tumefied 

 ifig. li. (0- and the cavity occupied by embryons invarious 

 stages of development, whilst those of them, however, which 

 are situated closest to the oral fissure are most developed; 

 consequentlv, therefore. the uppermost part of the gullet is 

 most dilated (fig. 6, 6). In the gastral cavity there are. 

 further, observed, a lev uudeveloped ova. enclosed in the 

 pedunculated capsules which issue from septula. 



It is a verv remarkable state of relations which. 

 here. exists. because the gullet really becomes transformed 

 into a uterus in which the young develope themselves. 

 In several polyps, it may be observed that the posterior 

 part of the body. just at the point where it passes Qver 

 into the branch, is tumefied, whilst the anterior part still 

 remains in the normal condition, but its tentacles have 

 begun to become glued together. and their extremities to 

 be curved inwards. When these polyps are opened, ova are 

 found in various stages of development, hut all of them 

 enclosed in their pedunculated capsules,^ usuallv one ovum 

 in each capsule. The gullet is not dilated. and is. either, 

 empty. or contains some foraminifera, remnants of the 

 nutritive substances absorbed. Manv of the ova have under- 

 gone the segmentation and are therefore impregnated. but 

 the true fætal-formation has scarcely commenced. As soon 

 as it commences, the larva ' — still enclosed in' the ovum 

 — relinquishes the capsule. and the gullet is now prepared 

 for the reception of the young. to undergo, there. their 



it* 



