77 



Polyperne ere paa deres yclre Flade omgivne af et 

 Ectoderm, Fig. 65, a, der kun adskiller sig fra det, der 

 beklæder Stammen og Grenene, ved at Cellerne danne 

 færre Lag. Ogsaa her sees lignende Slimkjertler som de 

 paa Stammen og Grenene, ligesom de fleste Spilder ligge 

 i Ectodermets indre Cellelag, hvor Cellerne ere mere eller 

 mindre aflange. Kun enkeltvis sees hist og her en Spikel 

 nedsænket i Bindevævet, men da er denne Bindevævs- 

 hulhed, hvori den ligger, beklædt med et Epithel, der er 

 en Forlængelse af Ectodermet. Indenfor den ydre Epithelial- 

 beklædning optræder et Lag hyalint Binclevæv, forsynet 

 med Binde vævslegemer og Nutritionskanaler, og fra hvis 

 indre Flade udgaa S Septa, Fig. 65. b. c, der fæste sig 

 paa Svælget og danne Kamrene, Fig. 65. Paa Binde- 

 vævets indre Væg ligger Muskellaget, Fig. 65, d, der gaar 

 over paa Septa saaledes nemlig, at de transverselle Muskler 

 ligge paa den ene og de longitudinelle paa den anden Side 

 af hvert Septum for at udbrede sig paa Svælget. Dette 

 Muskellag er overtrukket med et Endothel, der bestaar af 

 flere Lag runde Celler, lig dem, som ere omtalte ved de 

 store Kanaler i Stammen og Grenene. Men foruden 

 Endothelcellerne iagttages i Kamrene ligesom i Kanalerne, 

 der tildels kunne betragtes som Fortsættelse af disse, iso- 

 lerede, runde, klare Celler, indtil 0.010""" i Gjennemsnit, og 

 som har et fintkornet Protoplasmaindhold ; de ligne meget 

 hvide Blodlegemer hos de høiere Dyr og indeholdes i den 

 Ernæringsvædske, som gjennemstrømmer hele Polypkolonien. 

 Hos enkelte Polyper forlænger Mavehulheden sig ned i de 

 store Længdekanaler, og da sees Septa som Septula at 

 følge Kanalerne lige til deres Bund; hvor dette er Til- 

 fældet, tindes Generationsorganerne at udvikle sig paa 

 flere Septula i den øverste Del af Kanalerne, eller, om 

 man vil, i den forlæ.ngede Mavehulhed, imedens hos andre, 

 og det hos de fleste Polyper, forsnevrer Mavehulheden sig 

 snart og danner en meget trang Kanal, der vel aabner sig 

 i en af de store Længdekanaler, men som dog ganske ud- 

 fyldes af Endothelceller, saa at ingen Septula Andes der, 

 — og hos disse Polyper udvikle Generationsorganerne sig i 

 selve Mavehulheden. 



Svælget er langstrakt, cylindrisk ; dets uclvendige Flade 

 er beklædt med de tidligere omtalte Endothelceller, der 

 støde til et hyalint Bindevævslag. Lige paa Grændsen af 

 dette og Endothelet, men ligesom nedsænket i Bindevævet, 

 sees paa hver Side en bred Længderække af Spikier — 

 3 — 4 lidt paaskraasgaaende Spikier i hver Række — ime- 

 dens Midtpartiet af Svælget saavel paa Bug- som Byg- 

 siden er uden Spikier, Fig. 66. Fra Svælgets nederste 



whose cells are more oblong, and quite fill out the channel 

 in the minutest ducts. 



The polyps are, on their exterior surface, surrounded 

 by an ectoderm (fig. 65, a) differing, only, from that which 

 clothes the stem and the branches, in that the cells are 

 disposed in fewer layers. Here, also, similar mucous glands 

 to those seen on the stem and the branches are observed, 

 whilst, also, the greater number of the spicules are 

 situated jn the interior cellular layer of the ectoderm, 

 where the cells are more or less oblong. Only occasion- 

 ally is a spicule seen, here and there, embedded in the 

 connective-tissue, but in that case the connective-tissue 

 cavity in which it is situated is clad with an epithelium 

 which is a prolongation of the ectoderm. Inside of the 

 exterior epithelial covering, a layer of hyaline connective- 

 tissue appears, furnished with connective-tissue corpuscles 

 and nutritory ducts, and from whose inner surface 8 septa 

 proceed; (fig. 65, b. c) these are secured to the gullet and 

 form the chambers (fig. 65). The muscular layer is 

 situated on the inner wall of the connective-tissue (fig. 

 65, d) ; this is produced into the septa in such manner, 

 that the transversal muscles are placed on the one side, 

 and the longitudinal muscles on the other side of each 

 septum, so as to extend themselves on the gullet. This 

 muscular layer is clothed with an endothelium consisting 

 of several layers of cylinder-cells like those spoken of in 

 connection with the large ducts in the stem and the 

 branches. But besides the endothelial cells, there are ob- 

 served in the chambers, as well as in the ducts which in 

 a measure may be considered to be continuations of them, 

 solitary, pellucid, cylinder-cells, measuring up to 0.010 mm 

 in diameter, and occupied by a minute granular, proto- 

 plasmic substance, much resembling the white blood- 

 corpuscles pertaining to the higher-class animals ; these 

 cells are contained in the nutritory fluids which permeate 

 the entire colony of polyps. In a few polyps, the ventral 

 cavity is prolonged, downwards, into the large longitudinal 

 duct, and, there, septa are seen in the shape of septula 

 to follow the ducts right down to their bottom. Where 

 that is the case, the generative organs are found to devel- 

 ope themselves on several septula in the uppermost part 

 of the ducts, or, as it may be called, in the ventral cavity,, 

 whilst in others, and that the greater number of the 

 polyps, the ventral cavity rapidly contracts, and forms a 

 very constricted duct, which, sure enough, opens into one 

 of the large longitudinal ducts, but is, however, quite occupied 

 by endothelial cells, so that no septula are be observed 

 there ; in those polyps the generative organs develope them- 

 selves in the ventral cavity itself. 



The gullet is elongate and cylindrical; its exterior 

 surface is clacl with' the endothelial cells previously spoken 

 of, which connect to a layer of hyaline connective-tissue. 

 Exactly at the margin of this and the endothelium, but 

 as if embedded in the connective-tissue, a broad longitudi- 

 nal series of spicules is seen on each side — 3 — 4, some- 

 what diagonally running, spicules in each series — whilst 

 the mesial part of the gullet, both on the ventral and the 



