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8
spring med Epithelbeklædningen dannede stærke paalangs
gaaende Folder, som findes paa Spiserørets indre Flade.
Epithelet bestaar af et Lag langstrakte
Cylinderceller. der slutte tæt til hverandre ved Grunden, hvor
de ere fæstede til Bindevævet. Disse Cylinderceller have
en bred Basis og løbe noget tilspidsede henimod Cuticula.
Enkelte af dem ere bredere og større end de andre og
kunne svare til de Celler, Dr. Teuscher har anseet for
Kjertier hos Holothnria tuhdosa. Hvor Spiserøret gaar over
i Mavesækken er en næsten umærkelig Indsnøring.
Maven er lidt kolbeformig, Tab. I, Fig. 8, a,
omtrent 2,5""* lang, bredere fortil, smalere bagtil, hvor den
gaar over i Tarmen. Den har en intens rødviolet
Farve, er meget muskuløs, og synes i denne Henseende at
overgaa Svælget. Dens indre Flade er foldet, men det er
især paa den ventrale Del, at Folderne ere betydelig
fremragende, og her er Epithellaget ogsaa tykkere, imedens
Cuticula er smalere, end Tilfældet er i Svælget. Epithelet
• bestaar her af lignende Celler, som de, der ere beskrevne
for (Esophagus, kun ere de især paa Ventralfladen noget
længere, og have en smuk rød Farve, der hidrører fra deres
pigmenterte Indhold. Om disse pigmenterte Celler,
fornemmelig de store, fungere som Kjertier, skulle vi lade
staa derhen, usandsynligt er det dog ikke; thi de ere jo
noget forskjellige fra de øvrige Epithelceller. Idet Maven
gaar over i Tarmen, er der en liden Indsnøring af denne,
Fig. 8, b, som strax derpaa udvider sig og bliver
temmelig tyk.
Tarmen har, som sædvanligt hos Holothuriderne, tre
Bøjninger. Den første, nedadstigende Del, Fig. 8, c, ligger
imellem begge Ryggens Længdemuskler, og gaar bag til
Kloaken, derpaa slynger Tarmen sig til Venstre, gaar
fortil og ligger nu* i venstre Mellemrum paa Triviet, indtil
den naar Maven, Fig. 8, d, hvor den bøjer sig over til
højre Side, og løber saa bagtil i højre Trivium for at munde
ud i Kloaken, Fig. 8, e. Tarmens Vægge ere tyndere end
Mavens, kun henimod Kloaken antage de en tykkere
Karakter. idet Muskelhuden’ har en rigere Muskulatur.
Bindevævet er det samme hyaline, som tidligere omtalt, og paa
Tarmens indre Ventralflade iagttages temmelig tætstaaende
Længdefolder, der rage noget ind i Lumenet og ere
egentlig Fortsættelser af Mavens Længdefolder. Den udvendige
Flade har som sædvanligt et flimrende Peritonealovertræk.
Tarmkanalen er langs Bugfladen bunden til denne ved
Mesenteriet, der bestaar væsentlig af Bindevævstraade, hvori
enkelte Muskelfibre findes; men foruden dette Mesenterium
er der ogsaa nogle meget lange muskuløse Traade, hvoraf
with a thick. cuticle. The cornice-like processes form with
the epithelial integument the prominent longitudinal folds
that occur on the interior surface "of the oesophagus.
The epithelium consists of a layer of elongate,
cylin-dric cells, continuous at their bases, which are attached
to the connective tissue. These cylindric cells have the
base broad, becoming slightly acuminate towards the
cuticle. Some of them are broader and larger than others,
and correspond, it would seem, with the cells in Holothnria
tubidosa, supposed by Dr. Teuscher to be glands. At the
point where the oesophagus opens into the ventricle, occurs
a scarcely appreciable instriction.
The stomach is slightly clavate, Pl. I. fig. 8, a; it
measures 2.5"" in length, and is broader anteriorly than
posteriorly at the entrance to the intestinal canal. In colour it is
deep violet, with a vivid tinge of red. The stomach has very
considerable muscular development, surpassing apparently
in this respect the pharynx. Disposed over the inner
surface, occur a series of folds, of which those, on the
ventral portion more especially are very prominent; and here,
too. the epithelium is thicker, whereas the cuticle
exhibits-greater tenuity than is the ease in the skin of the gullet.
The epithelium consists here of cells similar to those —
described above — in the oesophageal integument; they are,
however, in particular on the ventral surface, somewhat
greater in length, and of a fine bright-red colour, arising
from their pigmentary contents. Whether these pigmentary
cells, more especially the large ones, perform the function
of glands, is a question we shall not attempt to decide;
improbable, however, it certainly is not. differing as they do
in some respects from the other epithelial cells. At the
pyloric, or intestinal, opening, the stomach is slightly
constricted, fig. 8, 6; it immediately however expands, the
walls attaining considerable thickness.
The intestine is triply convolute, a normal feature in
the Holothuriidæ. The first, descending portion, fig. 8. c.
extends down between the two dorsal longitudinal muscles,
passing backwards to the anal aperture; the intestine then
deflects sinistrously. protends forwards, and occupies the
left segment of the trivium, till it reaches the stomach, fig.
8, d. where, after making a dextral bend, it projects
backwards into the right segment of the trivium, to disembogue
into the cloacum. fig. 8, e. The walls of the intestine are
thinner than those of the stomach; not till they approach
the anal opening is greater compactness apparent, the
muscles in that part of the integument being more highly
developed. The connective tissue is the hyaline membrane
previously described. On the inner ventral surface of
the intestine occur a number of rather closely disposed
longitudinal folds, slightly projecting into the lumen —
prolations from the longitudinal folds of the stomach. Over
the outer surface extends the normal peritoneal membrane,
furnished with vibratile cilia.
The intestinal canal is webbed to, and along, the
ventral surface by the mesentery, which consists chiefly of
filaments of connective tissue, along with a few muscular
fibres; but, exclusive of this mesentery, there are a few ex-
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