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49
og her en Mængde temmelig tætstaaende Tverfolder. i hvis
Bindevæv iagttages stærke Kai-forgreninger, som paa sine
Steder danne smukke Net. Disse Karnet svare visselig til
dem. Semper har paavist at være tilstede i mange
Holo-thuriders Tarmfolder, og som han antager staa i
Respirationens Tjeneste, idet Søvandet skulde trænge op i
Tarmkanalen og saaledes komme i Berørelse med det paa
Tarmfolderne udbredte Karnet. *
Tarmen hos vort Dyr er fuldt udfyldt af den fine
graaligbrune Ler. som i Regelen danner Bunden paa de
Steder, hvor det lever. I dette Ler findes en Mængde
Foraminiferer (Globigeriner) og Diatoméer, som vistnok er
Dyrets vigtigste Føde. Dersom Søvandet trængte op
igjennem denne Lermasse, hvoraf Tarmen er- fuldproppet, vilde
upaatvivlelig^ dette Vand. naar det igjen udstødes, vise sig
at være mere eller mindre grumset, men saa er ingenlunde
Tilfældet. Vandet holdt sig klart, og nogeb Ind- og
Udstrømmen gjennem den nederste Aabning (Analaabning) var
ikke at iagttage, hvorimod Excrementproppe stundom
udfyldte ganske den nævnte Aabning, og kunde længe forblive
staaende deri.
Vi kunne ikke ifølge vore Observationer antage, at
der i Tarmen hos Trochostoma foregaar noget, der kan
sammenlignes med Aandedrættet hos enkelte Insekter.
Karnettet paa Tarmfolderne tjene snarere som et
Lymphesy-stem. der optager de i Tarmen præparerede Na>ringssafter
(Chymus) for at føre dem over i Blodet. Imedens Tarmen
altid var propfuld af den nævnte Ler. var Spiserøret
saagodtsom tomt, og i Maven var der vel endel af lignende
Lermasse, men den var langtfra udfyldt deraf. Det synes,
som om Fødemidlerne ikke opholde sig ret længe i Svælg
og Mave. men jages snart ned i Tarmen, hvor den
egentlige Fordpielse nok foregaar.
Noget Kjertelapparat i Tarmens. Mavens eller
Svælgets Vægge have vi ikke fundet, og det tør vel være
tvivlsomt, om noget saadant existerer hos vort Dyr. dersom
man ikke vil antage de tidligere omtalte isolerede klare
Celler, som findes i det indre hyaline Bindevæv, for
specielle Afsondringsorganer. for Lever; men derom kan der
vel neppe være Tale. Sikkert er det. at de brunlige
kjer-telformige Organer, der ifølge Sars skulde findes i Svælg
og Mave, og som han formener muligens kunde tjene som
Lever, ikke existere. De brunlige Legemer have vi ogsaa
seet; men de ere hverken enkelte eller sammensatte Celler,
der kunne optræde som Kjertler, de ere Klumper, der
dannes af det brunrøde Blodplasma, som tindes næsten
overalt i Legemet, og som meget let koagulerer.
Foruden det ovenomtalte Tarmindhold, fandt vi ogsaa
en Nematoide i temmelig stor Mængde. Det er sandsynlig,
at den lever som Parasit hos dette Dyr, da vi fandt et
Udviklingsstadium af den. i hvilket den spiralformig ligger
indkapslet i Tarmvæggen.
Den uorske Xordliavsexpeditiou. Dmiielssen f g Koren: Holothurider.
intestine. On the inner surface of the two first
convolutions. more especially that inclining downwards, are seen
every here and there numbers of rather closely arranged
transverse folds, through the connective tissue of which extend
well-defined vascular ramifications, having in places a
graceful, reticulate form. These vascular Assemblages correspond
unquestionably to those Semper has shown to occur in the
intestinal folds of many Holothurians, and which, in his
opinion, perform the office of respiratory organs, the
sea-water being forced up into the intestinal canal, and thus
brought in contact with the vascular net investing it.
The intestine in the specimen here described was full
of the greyish-brown clay which generally covers the bottom
in localities where this animal occurs. Such clay contains
an immense number of Foraminifera (Globigeriiue) and
Diatoms, which unquestionably constitute the chief food of
the animal. Now, assuming the sea-water to be forced up
through the olay with which the intestine is distended, it
would, when ejected, have a more or less turbid
appearance ; but such is not the case. The water continued
perfectly clear, nor could we detect any flux and reflux through
the lower opening (anal aperture); nay, fæcal pellets
sometimes stopped up the opening, and were not evacuated till
after a comparatively long interval.
Our observations do not lead us to infer, that the
intestine in Trochostoma is the seat of a functional process
corresponding to that of respiration in certain insects. The
vascular network on the intestinal folds would seem to serve
rather as a system of lymphatic vessels for the reception of
the alimentary juices (the chyme), to be afterwards
conveyed to the blood. The intestine was invariably filled to
repletion with the clay, whereas the oesophagus was almost
empty ; some of this clay. too. was found in the stomach,
by no means however sufficient to distend it. The food
would appear to remain but a short time in the oesophagus
and stomach, being speedily forced down into the intestine,
where 110 doubt digestion chiefly takes place.
No glands could be seen in the intestine, the
stomach. or the walls of the oesophagus, and it is very
doubtful whether any such exist, unless indeed the bright isolated
cells, previously mentioned, in the inner hyaline layer of
connective tissue be regarded as special secretory organs —
as a liver; but this is surely out of the question. It
is quite certain that brownish orgaus of a glandular form,
which, according to Sara, occur in the oesophagus and stomach,
and which lie regards as possibly performing the office of
a liver, do not exist. Brownish corpuscles, we, too. have
observed, but these are neither simple nor complex cells
that might serve the purpose of a liver, but mere lumpy
fragments of the brownish-re4 sanguineous plasma occurring
almost everywhere throughout the body, and which readily
coagulate.
Exclusive of the clay which, as mentioned above,
constitutes the chief contents of the intestine, we found a
Nematoid in considerable numbers. It probably exists in
this animal as a parasite, some of the individuals having
represented a particular stage of development, during which
it lies spirally incapsulated in the walls of the intestine.
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