113 



Scapus er brun; men indenfor den inkrusterede Skede er 

 Huden næsten hvid, spillende noget i det Rosenrøde. 

 Physa spiller svagt i det Kjødrøde. 



Ved Tversnit af Scapus viser det skedeforraige Over- 

 træk sig at beståa af en slimet Membran, hvori er indlei- 

 ret en Mængde brunagtige Sandkorn samt brunt Ler, uden 

 at der forresten tindes i Membranen nogen histologisk 

 Struktur. Tab. XIX. Fig. 7 a. Indenfor Membranen iagt- 

 tages Ectodermet, der bestaar af temmelig hoie Cylinder- 

 celler, forsynede med Kjerne og Kjernelegeme, Tab. XIX, 

 Fig. 7 b, og imellem disse Celler sees hist og her enkelte 

 Nematocyster. Det til Ectodermet stødende Bindevævslag 

 er meget bredt, fibrillært og temmeligt rigl forsynet med 

 Ernæringskanaler med sit Epithel og Bindevævslegemer 

 med en eller flere Udløbere, Tab. XIX. Fig. 7 c. Ned- 

 sænket i Bindevævet sees de for omtalte Papiller at være 

 dannet paa en lignende Maade som de hos Edwardsia 

 Andresi, nemlig ved en fast, membranøs, ægformet Kapsel, 

 hvis noget smalere Del, der med sin Aabning vender ud 

 mod Ectodermet. passerer igjennem dette og Skeden for 

 at aabne sig paa Overfladen i Papillen, Tab. XIX. Fig. 

 7 (1. Fra den indre Flade af Kapselen udgaa mange tynde 

 Bindevævstraade , som korrespondere med hverandre og 

 danne Net, Tab. XIX, Fig. 7 A e; men der, hvor flere 

 Traade mode hverandre, opstaar en bredere Bindevævsflade, 

 hvori sees Bindevævslegemer. Saavel Kapselens indre 

 Flade som Bindevævstraadene er beklædt med næsten 

 runde Epithelceller, forsynede med en rund Kjerne med 

 sit Kjernelegeme, Tab. XIX, Fig. 1 A f. B e. I Mas- 

 kerne synes lignende Epithelceller at ligge løsrevne, sam- 

 men med ægformede. tildels mere forlængede Celler, samt 

 kortere eller længere Nematocyster, Tab. XIX, Fig. 7 B 

 e, f. De ovale, løsrevne Celler ere upaatvivlelig vordende 

 Nematocyster; thi Overgangene kunde temmelig godt for- 

 følges, idet Celleme efterhaanden forlængede sig. indtil den 

 lange, stavformede Nematocyst var dannet. Traaden indeni 

 denne syntes at dannes af Kjernelegemet. Paa en næsten 

 fuldt udviklet Nematocyst kunde i den tykke Ende endnu 

 iagttages Rester af Kjernen. Tab. XIX, Fig. 7 A g. At 

 Nematocysterne dannes inden disse Kapsler, bekræftes end 

 yderligere ved Observationerne over Edwardsia fusca; i 

 llirc saadanne Kapsler saaes kun runde, ovale og lidt for- 

 længede Celler, ingen Stave, men vel Begyndelsen til deres 

 Dannelse. 



Henimod den indre Flade af det brede Bindevævs- 

 lag sees et smalt Belte af kun lidet udviklede. cirkulære 

 Muskler, Tab. XIX. Fig. 7 // ; men paa den indre Flade 

 er et Muskellag, bestaaende af Tver- og Længdemuskler, 

 Tal). XIX. Fig. 7 i. noget ligt det, der tilhører Edwardsia 

 Andresi. og som er beklædt med cylinderformede, ciUerende 

 Endothelceller. Paa Capitulum og Physa er Hudens Struktur 



Den norske Nordhavsexpeditisn. D. C. Danielssen: Actinida. 



consists of 2 triangular patches. The scapus is brown, but 

 underneath the encrusted sheath the integument is almost 

 white, with a play of colour approaching somewhat to 

 rose-red. The physa has a play of colour approaching a 

 faint flesh-colour. 



In a section of the scapus the vaginate covering 

 shows itself to consist of a mucous membrane in which a 

 mass of brownish grains of sand and brown clay is en- 

 trenched, without there being observed, otherwise, in the 

 membrane, any histological structure (Pl. XIX. fig. 7 a). 

 Inside the membrane the ectoderm is observed; it consists 

 of rather high cylinder-cells furnished with nucleus and 

 nucleus-corpuscle (Pl. XIX. fig. 7 /*). and between those 

 cells there are observed, here and there, a fe w nein- 

 atocysts. The layer of connective-tissue that adjoins the 

 ectoderm is very broad, fibrillous, and rather richly sup- 

 plied with nutritory ducts and their epithelium, and with 

 connective-tissue corpuscles having one or more prolonga- 

 tioiis (Pl. XIX, fig. 7 c). Embedded in the connective- 

 tissue, the previously mentioned papillæ are seen to be 

 formed in a similar manner to those of Edwardsia Andresi, 

 viz. by a finn, membranous, oviform capsule, whose some- 

 what uarrower portion, which with its aperture faces towards 

 the ectoderm. passes through the ectoderm and sheath. in 

 order to debouch on the surface of the papilla (Pl. XIX. 

 fig. 7 d). From the inner surface of the capsule there 

 issue nunierous connective-tissue rays that correspond 

 with each other and form a reticulation (Pl. XIX, fig. 7 

 A e), but at the spot where several filaments meet each 

 other, there arises a broader surface of connective-tissue 

 in which connective-tissue corpuscles appear. Both the 

 inner surface of the capsule and the connective-tissue ravs 

 are clad with, almost round epithelial cells, furnished with 

 a round nucleus and its nucleus-corpuscle (Pl. XIX, fig. 

 1 A f, B e). Similar epithelial cells appear to lie de- 

 tached in the meshes, together with oviform. partly more- 

 prolongated cells, and shorter or longer nematocysts (Pl. 

 XIX, fig. 1 B e, f). The oviform detached cells are, 

 indubitably, prospective nematocysts, because their transi- 

 tions could pretty well lie traced, in so far that the cells 

 became prolonged until the long rod-shaped nematocyst was 

 formed. The filament inside it appears to be formed from 

 the nucleus-corpuscle. In an almost completely developed 

 nematocyst there could still be observed, in the thick ex- 

 tremity, the remains of the nucleus (Pl. XIX, fig. 7 A g). 

 That the nematocysts are formed inside those capsules, is 

 still further confirmed by the investigations of Edwardsia 

 fusca; in several such capsules only round, oval, and 

 little-prolonged cells were observed, but no rods, only the 

 rudiments of their formation. 



Towards the inner surface of the broad layer of con- 

 nective-tissue a narrow belt of but little-developed cir- 

 cular muscles is observed (Pl. XIX, fig. 7 li), but on the 

 inner surface there is a muscular layer consisting of trans- 

 versal and longitudinal muscles (Pl. XIX, fig. 7 i), some- 

 what like that pertaining to Edwardsia Andresi, and which 

 is clad with cylindrical, eiliating endothelial cells. On the 



i:. 



