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33
Rinkii, og som kun maa betragtes som forskjellige
Udviklingsstadier.
De af Théel sårskilt beskrevne Celler, der findes paa
de sphæriske eller ovale Legemer, og hvortil han tror at
have fundet Nervegrene, ere efter vor Formening ikke andet
end Epithelcellerne paa Peritoneum, der .danner disse
Legemers Overtræk, hvor de ere temmelig spredte.
I det hyaline Parti af Bindevævet, nærmest’
Epithel-laget. ere Hjulene leirede. De findes især paa Rygfladen,
hvor de ligge temmelig tæt til hverandre, naar Dyret er
noget kontraheret; men spredes alt eftersom Kroppen
udvider sig. Paa Bugfladen ere de yderst sparsomme og
vanskelig at finde. Hjulenes Centraldel er paa den indre
Flade forsynet med en rund Knop. Fig. 5; forresten ere
de saa vel beskrevne af Dr. Théel. at vi kunne henvise
dertil. De ligge flade i Huden, rage ikke over dennes
Niveau, og ere ikke stilkede!
Dr. Théel beskriver et eget Slags Celler, der ligge i
Grupper, næsten som Drueklaser paa enkelte Steder i
Huden, saavel hos M. brevis, som hos Trochoderma elegans;
ogsaa vi have seet lignende; men vi ere tilbøjelige til at
antage dem for koagulerede Celler af Kropsvædsken. der
tilfældigvis ere komne ind i Huden. Saadanne
agglomere-rede Celler træffer man afsat snart paa Hudens indre
Flade, snart paa Tarmen, snart paa Mesenterium og de
Bindevævstraade. der binder Tarmen til Huden, og ere
stundom saa nøie fæstede, til disse Dele. at man’ let kunde
fristes til at antage dem for histologiske Elementer deraf.
De tolv Tentakler ere fuldstændig lig dem hos M.
Rinkii, og som af os ere afbildede; kun have de nogle
Cirrer niere end Rinkii.
Kalkringen. Fig. 6. a. er sammensat af ld Stykker,
der bærer 12 Spidser (Processer) paa den forreste Rand.
saaledes nemlig, at ethvert af de to dorsale Radialstykker,
der støde til det midterste dorsale Interradialstykke. er
forsynet med to Processer. Fig. G. b, b, ligesom Spidsen paa
de to midterste ventrale Radialstykker er den længste,
noget Sars har gjort opmærksom paa i hans Beskrivelse
over Oligotrochus rit r ens. I det Hele taget ligner
Kalkringen hos denne fuldstændig den hos M. breris.
Vandkarringen er som hos Synaptiderne i
Almindelighed ; den Poliske Blære er temmelig stor. ægformig.
Fig. 6. c.
Stenkanalen er meget kort. den har næsten S-Formen,
er meget bred indad hvor den munder ud i Vandkarringen.
Fig. 6, d, 7. d. Paa dens ydre Ende. der ved et stærkt
Ligament. Fig. 7. a, er bundet til Hudens indre Flade,
findes en bred Madreporplade, Fig. 7. b, der er ujævn paa
Overfladen af de fremragende Kalkpigge, og hvori den
Den norske Nordhnvse*i>edition. Danielssi-n ofr Koren: Holothurider.
visceral cavity. They assume, exclusive of the two forms
he has figured, several others, bearing some resemblance
to those of the spicules in Myr. Rinkii, and which must
be regarded merely as representative of the divers stages
of development.
The. cells on the spherical or ovate corpuscles,
specially described by Dr. Théel. and passing to which he
"believes to have detected nervous ramifications, are. in
our opinion, simply the epithelial cells of the peritoneum,
with which these corpuscles are invested when they occur
comparatively dispersed.
In the hyaline portion of the connective tissue,
immediately beneath the epithelial layer, are embedded the
wheel-shaped spicules. They occur in particular on the dorsal
surface, where they crowd together on a slight contraction
of the body, again dispersing when it expands. On the
ventral surface they are very sparingly distributed, nay
are difficult even to detect. The central portion of the
spicules is furnished on the inner surface with a round
knob. fig. 5; for the rest, they have been so excellently
described by Dr. Théel as to render further notice
superfluous. They lie in a plane with the skin, never projecting
above it. and are not pedunculate.
Dr. Théel also describes a peculiar kind of cells
occurring both in M. brevis and Trochoderma elegans; they
are airanged in groups, not unlike clusters of grapes, here
and there in the skin. We, too, have observed similar
cells, but are inclined to regard them rather as cellular
globules of coagulated perivisceral fluid that have chanced
to find their way into- the skin. Such agglomerate cells
are met with on the inner surface of the skin, on the
intestine. on the mesentery, and on the membranous filaments
that web the intestine to the skin; and they are so clbsely
connected with those parts as to present every appearance
of being histological elements.
The twelve tentacula are exactly similar to those of
M. Rinkii, as figured by us! save in their having a few
more cirrhi.
The calcareous ring, fig. 6, a, is composed of 10
segments (ossicles) and has on the anterior margin 12 acuminate
processes, arranged in such manner that each of the two
dorsal radial segments contiguous to the medial dorsal interradial
segment is furnished with two processes, fig. 6, b, b, the
process on each of the two medial ventral radial segments being
the longest, a distinctive feature pointed out by Sars in
his description of Oligotrochus tftrew. The general
structure of the calcareous ring in this species is the .same as
in M. brevis.
The water-vascular ring as in other Synaptidai; the
Polian vesicle rather large, ovate, fig. G, c.
The sand-canal very short, in form closely resembling
the letter S; within, at the point where it opens into the
water-vascular ring, exceedingly. broad, fig. 6, d, 7, d. On
its outer extremity, attached by a strong ligament, fig. 7. a,
to the inner surface of the skin, occurs a broad madreporic
body, fig. 7. b, and with this body, which the projecting
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