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synkninger i Bindevævet ere ikke saa dybe, og staa heller
ikke saa tæt i hinanden, og foruden de almindelige
Cylinderceller, som i Spiserøret, findes der i Epithelet en stor
Mængde pæreformige encellede Kjertier, Fig. 11, /
(Leverceller), der svare fuldkommen til Tarmkjertlerne hos
Bo-nellien. Disse Kjertier ligge tildels i Grupper, der kunne
sees med en stærk Loupe igjennem Tarmvæggen, Fig. 6,
k, l, m, o.
Naar den 5te Tverslynge har naaet hen til høire
Side, bliver den meget smalere. Tarmrøret løber nu i flere
Bøininger skraa fortil under de tidligere omtalte
paatvers-gaaende Slynger, lige henimod den første Tverslynge. Paa
denne Strækning gjør den en Mangfoldighed af smaa
Cir-cumvolutioner, Fig. 6, p, p. Nu bøier den sig hen mod
venstre Side, hvor den gjør en Bøjning for at løbe langs
denne i en horizontal Retning mod Kropshulhedens bagerste
Trediedel, Fig. 6, q, q, hvor den danner en Slynge, Fig.
6, r, for i samme horizontale Retning at gaa fortil imod
Midten af Kropshulheden, Fig. 6, s, her skraar den over
mod høire Side under de øvrige Tarmslynger; den bøier
sig nu i en skraa Retning mod Midtlinien af
Kropshulheden, Fig. 6, t, og gjør atter en Mængde Circumvolutioner,
indtil den gaar over i en paaskraa løbende Rectum, Fig.
6, u, der først udvider sig lidt, men bliver saa smalere,
idet den munder ud i Kloaken.
Fra den 5te Tverslynge og indtil Analaabningen, —
der svarer til deri Del hos Bonéllia viridis, som
Lacaze-Duthiers har kaldet Analdelen, — har Tarmrøret den samme
Bygning, som tidligere er angivet for den Del, der strækker
sig fra Spiserøret til 2den Tverslynge, og er følgelig uden
noget Kjertelapparat.
Langs Tarmrørets Bugflade, især paa den forreste
Del, sees et Bindevævsbaand, hvortil Bugmesenteriet er
fæstet, og hvori et Blodkar iagttages; paa den bagerste Del
er dette Bindevævsbaand tyndere. Det synes paa enkelte
Steder at stramme Tarmen saaledes, at dennes Bugflade
bliver foldet; men det er kun paa et Par Slynger, at saa
er Tilfældet.
Bugmesenteriet bestaar af en stor Mængde smalere
og bredere Bindevævstraade, hvori tildels findes
Muskelfibre, hvilke fæste Tarmrøret til Kropshulheden. Et
lignende Mesenterium, men langt zartere, iagttages ogsaa
langs Tarmens Rygflade, der fæster denne til
Kropshulhedens Rygflade.
Kloaken er bunden ved en Mængde stærke
fibro-muskuløse Baand til Kropsvæggen, hvilke udbrede sig
straaleformigt paa denne og danne derved ligesom et Telt,
Fig. 6, v, under hvilket 2de buskede Organer ere placerede,
et paa hver Side af Rectum. Tarmrørets ydre Flade er
forsynet med et flimrende Peritonealovertræk.
Den norske Nordhavsexpedition. Dauielssen og Koren: Gepliyrea.
canal, the walls are thinner; the depressions of the
epithelial layer (mucous membrane) in the connective tissue
are not so deep, or so close together; and exclusive of
the ordinary cylindrical cells (those in the skin of the
oesophagus, for instance), numbers of pyriform, unicellular
glands, fig. 11, / (hepatic cells), occur dispersed throughout
the epithelium — the exact analogue of the intestinal glands
in Bonéllia. Part of these glands are arranged in groups,
which may be seen, under a strong magnifier, through the
wall of the intestine, fig. 6, k, I, m, o.
On reaching the right side, the 5th transverse
circumvolution diminishes very considerably in thickness. The
intestinal canal now passes obliquely forward, twisting
repeatedly, beneath the transverse circumvolutions described
above, to the first circumvolution. On its course it forms
a great many small convolutions, fig. 6, p, p. It now bends
across to the left side, along which it protends, after making
a twist, in a horizontal direction, to the posterior third of
the perivisceral cavity, fig. 6, q, q, where it forms a
circumvolution, fig. 6, r, and then passes on, horizontally as
before, to the middle of the perivisceral cavity, fig. 6, s;
here it takes an oblique direction across to the right .side,
beneath the other circumvolutions, and then bends obliquely
on towards the mesial line of the perivisceral cavity, fig. 6,
t, again forming a number of convolutions, till it enters an
obliquely protending rectum, fig. 6, u, which expands a
little at its commencement, but grows narrower where it
disembogues into the cloacum.
From the 5th transverse circumvolution to the anal
opening, — which represents the part in Bonéllia viridis
termed by Lacaze-Duthiers the anal region, — the intestinal
canal exhibits the structure described above as
characterising the part that extends from the oesophagus to the 2nd
transverse circumvolution: hence it has no glandular
apparatus.
On the ventral surface of the intestinal canal — more
particularly the anterior part — is seen a membranous
band (webbed to the ventral mesentery), in which there
is a blood-vessel: this membranous band has its posterior
portion thinner than the remainder. In some places, it
would appear to stretch the intestine, corrugating the
ventral surface of the latter; this is the case, however, only
with one or two of the convolutions.
The ventral mesentery consists of numerous filaments
of connective tissue, in some of which are muscular fibres,
that serve to attach the intestinal Canal to the
perivisceral cavity. A similar mesentery, but far more delicate
in structure, is seen, too, on the dorsal surface of the
intestine, which it webs to the dorsal surface of the
perivisceral cavity.
The cloacum is webbed to the wall of the body by
numei’ous strong fibro-muscular bands, which, radiating on
the latter, form, as it were, a tent-like enclosure, fig. 6, v,
under which are placed two bunchy organs, one on either
side of the rectum. The outer surface of the intestinal
canal is invested with a ciliated peritoneal tunic.
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