60 



oftest skjules ganske af disse. Grenene ende i Alminde- 

 lighed i en bred Udvidning, der ligesom Stammens øverste 

 Ende bærer 2—3 Grupper Polyper. Imellem de fuldt 

 udviklede Polyper træffes hyppig ganske smaa. som netop 

 have gjennembrudt Coenenchymet. Baade Stammen. 

 Grenene og Smaagrenene ere rige paa Kalkspikler, Fig. 1. 2. 



Polyperne ere 8 mr " lange, ikke retraktile. med en tem- 

 melig lang Bagkrop. Kroppen er 5""" lang. cylindrisk. 

 noget bredere op imod Tentakelskiven og forsynet med 8 

 fremragende Længderibber. dannede af Spilder. Tentak- 

 lerne ere 3""" lange og have Spilder paa den aborale Side. 

 Pinnulerne ere korte, uden Spikier, Fig. 3. 4. 



Hele Zoanthodemet. undtagen Basaldelen, er saa 

 gjennemsigtigt. at man i levende Live kan iagttage Skille- 

 væggene og Længdekanalerne i Stammen, Mesenterial- 

 filamenterne og Svælget hos Polyperne. 



Zoanthodemets Bygning. 



Stammen. Grenene og Smaagrenene ere udvendigt be- 

 klædte med et Ectoderm, der bestaar af flere Lag polyæ- 

 driske Celler, som have en tynd Membran, ere 0,007 mBI 

 store 'og have en rund. næsten central Kjerne, 0.003""", 

 omgiven af yderst sparsomt Protoplasma, Fig. 5, a: men 

 imellem disse polyædriske Celler sees, især i det dybere 

 Lag, afiange Celler af omtrent samme Størrelse, med en 

 rund Kjerne, rigere omgiven af Protoplasma, Fig. 5. b, 

 samt desforuden kolbeformige Celler med en lang Hals, 

 der strækker sig op til Ectodermets Overflade. Disse 

 kolbeformige Celler ere stundom ganske tomme og se ud 

 som Vacuoler, men hyppigt ere de fyldte med en yderst 

 fintkornet Masse, som skjuler en næsten rund Kjerne. 

 der ligger ned mod Bunden af Cellen. De ere upaatviv- 

 lelig encellede Slimkjertler, 0.0 17""" lange og 0.008' 7 ™ 

 brede i den brede Ende, ere tilstede i stor Mængde og ligge 

 dels enkeltvis, dels i Grupper, Fig.. 5, c. Indenfor Ecto- 

 dermet er et hyalint Bindevævslag, rigt paa Ernærings- 

 kanaler og Binde vævslegemer, Fig. 5, e; det er tykkere 

 paa Stammen end paa Grenene, men er i det Hele tåget 

 forholdsvis tyndt, Fig. 5, cl, og fra dets indre Flade udgaa 

 Forhengelser. der straaleformigt konvergere indad mod 

 Centrum og danne Coenenchymet med dets Kanaler. 



Længdekanalerne ere meget vide, saa at Coenenchymet 

 bliver temmelig sparsomt, ikke saa bredt som hos Slægterne 



The branches are, quite from their root, occupied, partly, 

 by single polyps, and partly, by groups of 3—5 polyps, 

 but. principally, by branchlets, which are, everywhere, so 

 richly beset with polyps, that they are, in general, quite 

 concealed by them. The branches terminate, usually, in 

 a broad dilation which, like the uppermost extremity of 

 the stem, carries 2—3 groups of polyps. Between the 

 fully developed polyps, quite minute ones are frequently- 

 met with, that have just recently emerged from the sarco- 

 soma. Both, the stem, the branches and the branchlets, 

 are rich in calcareous spicules (figs. 1. 2). 



The polyps measure 8 mm in length, are non-retrac- 

 tile, and have a tolerably long posterior body. The body 

 measures 5""" in length, is cylindrical, somewhat broadest 

 up towards the tentacular disk, and it is furnished with 

 8 protuberant longitudinal ribs formed of spicules. The 

 tentacles measure 3 mm in length, and are furnished with 

 spicules on the aboral side. The pinnules are short and 

 devoid of spicules (figs. 3. 4). 



The entire Zoanthodem, except the basal part, is so 

 translucent that, in the live state, the divisional walls and 

 the longitudinal ducts in the stem, also the mesenterial 

 filaments and gullet of the polyps, may be observed. 



The structure of the Zoanthodem. 



The stem, the branches, and the branchlets are clad, 

 exteriorly, with an ectoderm, consisting of several layers 

 of polyhedrical cells with a thin membrane, and measuring 

 0.007""" in diameter, and these contain a round, almost 

 central nucleus, measuring 0.003""", enclosed by an ex- 

 tremely sparing protoplasm (fig. 5, a); but between these 

 polyhedrical cells there are seen, especially in the deeper 

 layers, oblong cells of about the same size, which contain 

 a round nucleus more richly enclosed by protoplasm (fig. 

 5, b), also, in addition, clavate-formed cells with a long 

 neck, which extend themselves up to the outer surface of the 

 ectoderm. These clavate-formed cells are sometimes quite 

 empty and appear like vacuoli. lutt most frequently they 

 are filled with an extremely minute granular substance 

 that conceals a nearly round nucleus placed down towards 

 the bottom of the cell. They are, without doubt, uni- 

 cellular mucous glands, and measure 0.01 l mm in length, and 

 0.008""" in breadth at the broad extremity; they are pre- 

 sent in great abundance, and are situated partly singly, partly 

 in groups (fig. 5, c). Inside of the ectoderm there is a layer 

 of hyaline connective tissue, rich in nutritory ducts and 

 connective tissue corpuscles (fig. 5, e) ; this layer is thicker 

 in the stem than in the branches, but, taken altogether, it 

 is relatively thin (fig. 5, d): from its inner surface pro- 

 longations proceed, converging radially, inwards, towards 

 the centre, and forming the sarcosoma with its ducts. 



The longitudinal ducts are very wide, so that the 

 sarcosoma becomes pretty sparing, and not so broad as in 



