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44
uppåt, hvarigenoni den af dem beldädde anden af kalkaxeln
kommer att hänga et stycke ned i ändblåsan."
Umbellula encrinus har, som vore Beskrivelser
paa-viser, ingen Endeblære; den ender nedad sædvanligvis
noget afstumpet med en Skraatia.de; Septum transversale
med det omtalte Belte deler den nederste Del i en
Ven-tral- og Dorsalkanal, hvoraf den sidste er videst, og som
vi senere komme til at omtale, imedens Sidekanalerne
indsnevres noget; men samtlige Kanaler stode til det eneste
Hulrum, som tindes nedenfor det transversellc Septum, og
som er det Fællesrum, hvori de 4 Længdekanalers Indhold
modes. Hvor indviklet end den anatomiske Bygning synes
at være i det nederste Parti af den bulbøse Del. saa
nærmer den sig dog meget til Bygningen hos Pennatulideriie
i Almindelighed; sagtens er Septum transversale meget
lidet, men det tindes dog. og det nævnte Bolte synes ved
sin større Længde at skulle hjælpe noget paa det, saa at
Delingen af det nederste Rum faar en længere l
dstraik-ning, imedens det Forhold. Dr. Lindahl har beskrevet, er
ganske fremmed for Pennatulideriie.
De 4 Septa, dér dele Stokkens Indre i 4
Længdekanaler, udgaa fra den indre Ooonenchymvæg og fæste sig
paa Kalkaxens Skede, med hvilken de smelte sammen.
Der er en liden Strækning i den øverste, smale Del af
Stilken, hvor Septa, idet de udgaa. fra Coenenchymvæggen,
ere ganske hele, det vil sige ikke gjennembrudte; men
saavel i den skedeforinige Udvidning og i Rachis, som i hele
den øvrige Del udgaa Septa med stærke Bindevævsbjelker,
der fornemmelig i Bulbus staa langt fra hverandre, og
hvorved fremkommer større eller mindre aflange Aabninger,
gjennem hvilke den ene Længdekanal kommunicerer med
den anden, Tab. VIII, Fig. 32, e. Nede i Bulbus og oppe
i den skedeformige Udvidning staa disse Aabninger meget
tæt sammen og ere større, saa at Kommunikationen i clisse
Dele maa være meget livlig.
Septa dannes af en tyk, fast, hyalin
Bindovævsmom-bran (Mesoderm?), hvori findes en stor Mængde fine,
forgrenede Saftkanaler, der kommunicere med hverandre, og
hvis Lumen ganske or udfyldt af Epithcl, bestaaende af
lidt aflange Celler med Kjerne og kornet Indhold, Fig. 36, a.
Begge Sider af Septa ere beklædte med Epithel, der
bestaar af flere Lag runde Celler, lignende dem, som beklæde
Lamgdekanaloriie. Disse Celler ere runde, have en tynd
Membran og en lidt excentrisk, rund Kjerne, omgiven af
en yderst finkornet Masse (Entoclermceller). De omtalte
Saftkanaler ere forsynede med storre eller mindre Laguner,
hvori Epithelbeklædningeii ikke ganske udfylder Lumenet.
Muskler findes ikke i Septa.
Foruden disse 4 Længdekanaler, der ere
eiendommelige for Pennatulidebygningen, beskriver Dr. Lindahl endnu
form their bottom. The septa referred to make, thus, a
strong curve upwards, through which, the extremity of the
calcareous axis which they cover, extends a little into the
terminal vesicle.
As our description shows, Umbellula encrinus, has no
terminal vesicle. It terminates downwards, generally,
somewhat truncated, with a diagonally sloping surface. The
septum-transversale, with the band already spoken of;
divides the lower part into a ventral and dorsal canal; of
these, the last named is the widest, and we shall,
subsequently, come to speak of it; whilst, the lateral canals
become somewhat contracted ; but, the whole of the canals open
into the only cavity which is found below the transversal
septum, and which, forms the common chamber in which
the contents of the 4 longitudinal canals meet. However
complex the anatomical structure seems to be in the lower
part of the bulbous portion, yet, it approaches much, in
similarity, to the structure of the Pennatulidæ, in general; certainly
the septuiu-trausversalo is very small, but. still, it is found
there, and the baud we have spoken of would appear,
by it,s greater length, as if it was intended to supplement
it, so that, the division of the lower space might attain a
longer extent; but the relations described by Dr. Lindahl
are quite foreign to the Ponnatulida;.
The 4 septa which divide the interior of the stalk
into 4 longitudinal canals, proceed from the inner wall of the
sarcosoma, and attach themselves to the sheath ol’ the
cal-carous axis, with which they become filfcod. There is a
small extent in the superior narrow part of the stem, where
the septa, as they proceed from the wall of the sarcosoma.
are quitö entire, that is to say, are not perforated; whilst,
both, in the sheath-formed dilation, and in t he rachis, as well
as, in all the other parts, the septa issue as strong connective
tissue rods, which, especially in the lmlb, are placed far
apart from each other, forming larger or smaller oblong
openings, through which the one longitudinal canal
communicates with the other (Pl. VIII, fig. 32, ’-)• Down in
the bulb, and up in the sheath-formed dilation, these
openings are placed very close together, and are larger, so
that, the circulation in those parts must be very active.
The septa are formed, of a thiele, firm, hyaloid
membrane of connective-tissue (Mesodermf) in which is found,
a multitude of minute, (lactiferous ramifications
communicating with each other; and whose channels are quito
filled up by epithelium, consisting of slightly oblong cells
containing a nucleus and granular contents (fig. 36, a).
Both sides of the septa are clad with epithelium, consisting
of several layers of circular cells like those which clothe
the longitudinal canals. These cells are round, and have a thin
membrane; and they contain a somewhat eccentric round
nucleus, surrounded by an extremely minute granular substance
(Entoderm cells). The duetiferous ramifications which wo
have spoken of, are furnished with larger or smaller lagunes :
in which, the epithelium covering does not quite fill the
channel. No muscles are found in the septa.
Besides these 4 longitudinal canals; which are
peculiar to the Pennatulida’s structure; Dr. Lindahl describes,
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