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31
Stichaster aibulus, (Stimpson) Verrill.
Tab. VIII, Fig. 13—15.
1842. Asteracanthion rosens, pars, Müller & Troschel.
Syst. der Asteriden, pag. 17.
1853. Asteracanthion aibulus, Stiinpson. Synops. Mar.
Invert. Grand-Manan, pag. 14, pl. XIV, fig. 5.
1855. Asteracanthion problema, Steenstrup. Vid. Medd.
Nat. Forening i Kjøbenhavn 1854, pag. 240.
1857. Asteracanthion problema, Lütken. Oversigt over
Grønlands Echinodermata, 1877, pag. 30.
1863. Asterias albula, Stimpson. Proc. Acad. Nat. Sc.
Philadelphia 1863, pag. 142.
1866. Stichaster albulus, Verrill. Proc. Boston Soc. Nat.
Hist. Vol. X, pag. 351.
1869. Stichaster albulus, Ed. Perrier. Stellerides du
Museum. Arch. d. Zool. expér. & gen. Vol. IV,
pag. 346.
1878. Asterias albulus, Marenzeller. Die Coelenteraten,
Echinodermen unci Würmer, der k. k. øst.-ung.
Nordpol-Expedition. Denkschr. der kais. k. Acad.
der Wissensch. 35t B., pag. 283.
1881. Stichaster albulus, Duncan & Sladen. A Mem. on
the Echinod. of the Arctic Sea to the West of
Greenland 1881, pag. 29.
Denne i fiere Henseender ret mærkelige Søstjerne har
været Gjenstand for fiere Forskeres Undersøgelser, af hvilke
vi kunne nævne Stimpson, Steenstrup, Lütken, Duncan &
Sladen. Paa Nordhavsexpeditionen blev der funden en
hel Del Exemplarer langs Spitsbergens Kyster, hvor den
forekom temmelig hyppigt.
Vi have havt Anledning til at observere den levende
i 14—15 Dage, og Resultaterne af disse Observationer i
Forbindelse med den Undersøgelse, vi have anstillet paa
Spiritusexemplarer, skulle vi nu meddele.
Som bekjendt frembyder Stichaster albulus den
Mærkelighed, at den i en vis Periode af sit Liv kaster en eller
flere Arme, og saa reproducerer nye. Denne Proces
foregik paa følgende Maade. Lige ved Grunden af en Arm
viste der sig en yderst fin Linie, der omspændte Rygfladen
til henimod Bugfuren; ved stærk Loupeforstørrelse saaes
denne Linie egentlig at være en fin Fure, der blev alt
dybere og dybere, idet Huden ved Absorbtion paa dette Sted
efterhaanden blev tyndere, saa at der efter en Tid af 14
Dage virkelig opstod en Spalte, der næsten ganske
gjennemtrængte Hudens Tykkelse. Paa Bugfladen viste der sig i
den omtalte Tid intet Tegn til en saadan Spaltning.
Skiveranden, hvorfra Armen paa Rygsiden var begyndt at
skilles, krængede sig lidt nedad og afrundedes; men nogen
fuldstændig Adskillelse iagttoges ikke. Dette Phænomen
observeredes paa et 5-armet og et 6-armet Individ.
Af fortsatte Undersøgelser paa de i Spiritus
opbevarede Exemplarer, af hvilke vi vare i Besiddelse af mange
Stichaster albulus, (Stimpson) Verrill.
Pl. VIII, figs. 13—15.
1842. Asteracanthion roseus, pars, Müller & Troschel.
Syst. der Asteriden, pag. 17.
1853. Asteracanthioyi albidus, Stimpson. Synops. Mar.
Invert. Grand-Manan, pag. 14, pl. XIV, fig. 5.
1855. Asteracanthion problema, Steenstrup. Vid. Medd.
Nat. Forening i Kjøbenhavn 1854, pag. 240.
1857. Asteracanthion problema, Lütken. Oversigt over
Grønlands Echinodermata 1877, pag. 30.
1863. Asterias albula, Stimpson. Proc. Acad. Nat. Sc.
Philadelphia 1863, pag. 142.
1866. Stichaster albulus, Verrill. Proc. Boston Soc. Nat.
Hist. Vol. X, pag. 351.
1869. Stichuster albidus, Ed. Perrier. Stellerides du
Museum. Arch. d. Zool. expér. & gen. Vol. IV,
pag. 346.
1878. Asterias albulus, Marenzeller. Die Coelenteraten,
Echinodermen und Wurmer, der k. k. øst.-ung.
Nordpol-Expedition. Denkschr. der kais. k. Aead.
der Wissensch. 35t B., pag. 283.
1881. Stichaster albulus, Duncan & Sladen. A Mem. on
the Echinod. of the Arctic Sea to the West of
Greenland 1881, pag. 29.
This, in many respects, very remarkable starfish, has
been the object of the researches of many naturalists,
amongst whom, we may mention, Stimpson, Steenstrup,
Lütken, Duncan and Sladen. During the North-Atlantic
Expedition, numerous specimens were obtained along the
coasts of Spitzbergen, and, it was rather frequently met
with, there.
We have had the opportunity of observing it for 14—
15 days, alive, and, will now state the result of these
observations, combined with the examination we have made,
of specimens preserved in spirit.
As is known, Stichaster albulus presents the
peculiarity, that at a certain period of its life, it casts, one or
more rays, and reproduces them anew. This process
proceeds in the following manner. Close to the origin of a
ray, there appears an extremely fine streak spanning the
abactinal surface nearly to the ventral furrow. With the
assistance of a powerful magnifyer, this streak is seen to
be, really, a minute fissure, which gradually, becomes deeper
and deeper, owing to the integument, in this situation,
becoming by absorption, gradually thinner, so, that, after the
lapse of 14 days, there is really developed a fissure which
almost quite penetrates the integument. During the time
specified, there was no appearance of a similar fissure on
the ventral surface. The diskal margin from which the ray
had begun to separate on the dorsal surface fell in slightly,
and became rounded off, but complete separation was not
observed. This phenomenon was observed, in a 5-rayed,
and, also, in a 6-rayed specimen.
From continued examination of the specimens preserved
in spirit, of which, we were in posession of many, in
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