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27
Tjeneste. Han formener da. at et Parti af dem
skuldejud-føre Secretionsorganets Rolle, imedens et andet kunde
fungere som Lunger.
Ifølge vore Undersøgelser, som rigtignok ere foretagne
paa et enkelt Exemplar, opbevaret i Spiritus, hvilket dog
blev observeret og tegnet i levende Liv, antage vi. at de
heromhandlede Organer hos Hamingia ere analoge med
Holothuridernes saakaldte Lunger; men som vi for
Molpa-didernes Vedkommende have paavist at være
Tarmappen-dices (Secretionsorganer), der intet have med Respirationen
at bestille. At disse Organer hos Hamingia ogsaa ere
Af-sondringsapparater og ikke Lunger, synes at fremgaa ikke
alene af deres Bygning, men ogsaa af den Omstændighed,
at de ikke staa i nogen Forbindelse med Blodcirculationen.
I det Døgn, Dyret blev observeret i levende Liv,
aabnede Kloakaabningen sig kun saa ofte Excrementerne
bleve udstødte; noget Søvand kunde ikke trænge ind
igjennem den ved en stærk Sphincter lukkede Aabning, ligesom
Endetarmen og Kloaken viste sig at være propfulde af de
før beskrevne Excrementer. Men det staar ikke til at
nægte, at de her omtalte Organer ere noget forskjellige fra
Holothuridernes benævnte Lunger. Disse, der hovedsagelig
bestaa i større og mindre Samlinger af blæreformige
Blind-sække, staa ikke i nogen directe Communication med
Krops-hulhedens Fluidum. Sagtens yttrer Semper, at han
formener at have iagttaget en Aabning paa Blærerne; men
ingen anden Forsker har observeret dette.
Hos vor nye Slægt er der ligesom hos Bonéllia en
tragtformig, vid Aabning paa de beskrevne slangeformige
Rør, forsynet med lange Oilier, hvori Kropsvædsken efter
al Sandsynlighed optages; men om den saaledes optagne
Kropsvædske undergaar paa denne Vei nogen Forandring,
eller om den atter jages ud i Hulheden, se det er et
Spørgsmaal, vi ikke kunne besvare, da vi dertil ikke have havt
Materiale nok. Men skulle vi indlade os paa en Hypothese,
saa var det den, at disse Organer, som vi antage for
Secretionsorganer, tjene til at rense og forsaavidt ogsaa til at
fornye Kropsvædsken; de virke, om man saa vil, som et
Slags Nyrer.
Circulationssystemet.
Vore Undersøgelser over Kredsløbet ere vistnok
ufuldstændige; men Skylden herfor tør mest ligge i det
mangelfulde Materiale.
Naar Dyret er aabnet fra Rygsiden, iagttages paa
Mundhulhedens ydre Flade en korktrækkerformig, hvid,
glindsende. Kanal, der er Rygkarret, Fig. 6, x. Dette
løber fortil langs Mundhulhedens Rygflade, lige til dennes
forreste Ende, hvor det deler sig i to Grene, en til hver
Side. Det tiltager i Tykkelse, alt eftersom det kommer
længere bag mod Svælget, og er slangeformig bugtet,
saalænge det løber paa Mundhulheden, Fig. 14, a. Naar det
forlader denne, bliver det tykkere, næsten lige, gaar under
his opinion, perform the office of a secretory organ, and
the other that of lungs.
Our own results, based, it is true, on the examination
of a single specimen, preserved in spirits, which was
however observed and figured while alive, lead us to regard
the aforesaid organs in Hamingia as the analogue of the
so-called "lungs," or "respiratory trees," in the Holothuriidce,
but which, in the case of the Molpadidæ, we have shown
to be intestinal appendages (a secretory apparatus), having
nothing whatever to do with respiration. And that these
organs in Hamingia are in like manner endowed with a
secretory, and not a respiratory function, may be inferred,
not only from their structure, but also from the fact of
their being nowise connected with the circulation of the
blood.
During the 24 hours the animal was kept alive, the
cloacum was never once seen to open, save for the discharge
of the fæces. A powerful sphincter, which closes up the
aperture, effectually prevented the ingress of sea-water; and
besides, the rectum and the cloacum were both found to
be full of the fæcal pellets described above.
Meanwhile, it is not to be denied, that the organs [in question
differ somewhat from those termed "lungs," or "respiratory
trees," in the Holothuriidce. The latter, chiefly consisting
of larger and smaller assemblages of vesicular cæca, have
no direct communication with the fluid of the perivisceral
cavity. True, Semper alleges to have observed an opening
on the surface of the vesicles, but no other zoologist has
recorded its occurrence.
In our new genus, as in Bonéllia, the sinuous tubes
described above exhibit a wide, funnel-shaped aperture,
furnished with long .cilia, in all probability for the
reception of the perivisceral fluid; but whether this fluid undergo
any change on its passage, or be again ejected into the
hollow of the .body, is a question we are not at present
prepared to answer, having lacked sufficient materials for
conclusively deciding it. But were we to venture an
hypothetical explanation, it would be this, that the organs in
question, whose function we regard as secretory, serve to
purify, and so far therefore to renew, the perivisceral fluid;
their action being, we may say, nephritic.
Circulatory System.
Our investigation of this system in Hamingia is
decidedly incomplete; but this will, we trust, be found to
arise chiefly from insufficiency of materials.
On opening the animal on the dorsal side, a white,
glistening, spirally twisted canal is seen extending along
the outer surface of the buccal cavity. This is the dorsal
vessel, fig. 6, x, which passes forward along the dorsal
surface of the buccal cavity straight to its anterior
termination, where it divides into 2 branches, one on either
side. It increases in thickness the nearer it approaches
the gullet, and retains a sinuous course on the buccal
cavity, fig. 14, a, after crossing which it grows thicker, and
4*
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