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22
ved Bindevæv ere sammenbundne til en Hud. Fig. 4. d.
Længdemusklerne ere bredere, ligge indenfor
Ringmusklerne og danne ligeledes en sammenhængende Hud,
Fig. 4, e.
Indenfor Længdemusklerne, altsaa nærmest
Kropshulheden, kun skilt fra denne ved Peritonealovertrækket, findes
Skraamuskellaget, Fig.. 4, f, hvis Muskler ere ligesaa stærke
som Længdemusklerne, men ere fjernede noget længere fra
hverandre, hvorved det sammenbindende Bindevæv bliver
noget bredere. Ogsaa dette Lag danner en
sammenhængende Hud.
Sammenlignes nu Huden hos Hamingia med
Bonelliens, saa vil der findes baade Overensstemmelser og
Afvigelser.
Efter Schmarda1 skal der i Bonelliens Hud være et
udpræget Epitheliallag, bestaaende af Cylinderceller,
indenfor hvilket skal findes et maskedannende Hudlag, som
dannes af stærke sammenvævede Cellevævsfibre og Kar.
I dette Lag fandt Schmarda enkelte Pigmentceller og
større Hobe af samme, hvilke forenede sig til kjertelagtige
Organer. Indenfor dette Lag angiver han Muskellaget
bestaaende af Længde- og Ringfibre; paa den forreste
Kropsdel føier sig dertil skjæve Muskelfibre.
Allerede Lacaze-Duthiers2 har paavist, at der ikke
findes noget særegent Kjertelapparat i Huden hos Bonellia,
hvilket ogsaa stemmer overens med Gr aber s3 Undersøgelser.
Denne Forsker betvivler stærkt Tilstedeværelsen af
Cylin-derepithellaget; derimod tror han at have fundet en af
talrige Porekanaler gjennemboret Cuticula, indenfor hvilken
han angiver et kornet Matrixlag, i hvilket findes
kjerne-agtige Indleiringer, snart enkeltvis, snart i Grupper.
Indenfor dette Matrixlag har han fundet det egentlige
Bindevævslag, der bestaar af hyalint Bindevæv, hvori findes
sparsomt Bindevævslegemer. Sammenvævede Cellevævsfibre og
Kar har Graber ikke fundet. Det vil heraf sees, at Huden
hos Hamingia nærmer sig i histologisk Henseende meget
til Bonelliens Hud ifølge Grabers Iagttagelser; men afviger
dog noget fra den. Saaledes er Cuticula langt fra saa
bred og heller ikke gjennemboret af Porekanaler hos
Hamingia, som Tilfældet er hos BonélMa; noget Matrixlag
findes ikke, derimod et hyalint Bindevævslag med
ind-leirede, tildels pigmenterede Celler, nogenlunde svarende
til hvad der findes hos Bonellia. Endelig har Hamingia
et tredie Muskellag, nemlig de skraa Muskler, som Graber
aldeles ikke omtaler hos Bonellia, imedens Schmarda
angiver. at paa dennes forreste Kropsdel føier skraa Muskler
1 Schmarda. Denkschrift. der k. k. Akad. der Wissenschaft in
Wien. Tom. IV, pag. 117, pl. 4—7.
a Lacaze-Duthiers. Recberclies sur la Bonellie. Annal, des Sciences
nat. III Série. Tome X, pag. 53.
8 Graber. Sitzb. der Akad. der Wissenschaften. Wien. IteAbth.
Jan. Heft. Jahrgang 1873.
slender fibrils, which, being webbed together by connective
tissue, constitute a continuous membrane, fig. 4,. d.
The longitudinal muscles are broader, lie underneath
those of the annular layer, and constitute, like the latter,
a continuous membrane, fig. 4, e.
’ Underneath the longitudinal muscles — accordingly
nearest the perivisceral cavity, with only the peritoneal
tunic between — is seen the oblique layer, fig. 4, f, the
muscles of which are as strong as those in the longitudinal
layer, but somewhat farther apart, giving greater, breadth
to the. connective tissue that webs them together. This
layer, too, constitutes a continuous membrane.
On comparing the skin in Hamingia with that in •
Bonellia, it will be found to exhibit both agreement and
difference.
According to Schmarda,1. the skin in Bonellia has a
well developed epithelial layer, consisting of cylindrical
cells, underneath which is said to extend a reticulated
teg-umentary layer, composed of strong interwoven vessels and
fibres of cellular tissue. t
In this layer, Schmarda found a few isolated pig-,
mentary cells, and agglomerations of such, which,, uniting,
formed glandulous organs. Underneath this layer, extends,
he states, the muscular layer, composed of longitudinal and
annular fibres, to which are united, on the anterior portion
of the body, oblique muscular fibres.
Years ago, Lacaze-Duthiers2 showed there was no
special glandular apparatus in the skin of Bonellia; and
since then, Graber3 has been led to form a similar
conclusion. Indeed, that observer very much questions the
existence of a cylindric epithelial layer, whereas he believes
to have detected a cuticle perforated by canaliculated pores,
extending underneath a granulated layer of matrix,
throughout which were dispersed, both isolated and in groups,
agglomerations of nucleal corpuscles. Underneath this layer
of matrix, was the true layer of hyaline connective tissue,
sparingly furnished with corpuscles of connective tissue.
Interwoven fibres of connective tissue, and vessels, Graber did not
observe. Hence it is obvious, according to Graber’s investigation,
that the skin in Hamingia bears, histologically, considerable
resemblance to that in Bonellia, though not strictly
agreeing. Thus, for instance, the cuticle is far less broad in
Hamingia than in Bonellia, nor is it perforated by
canaliculated pores; moreover, it has no layer of matrix; but
there is a layer of hyaline tissue, with cells, in part
pigmentary, much the same as in Bonellia. Finally, Hamingia
is furnished with a third muscular assemblage, viz. the
oblique layer, of which Graber makes no mention whatever
as occurring in Bonellia, whereas Schmarda distinctly states,
1 Schmarda. Denkschrift. der k.’ k. Akad. der Wissenschaft in
Wien. Tom. IV, pag. 117, pl.\4—7.
4 Lacaze-Duthiers. Recherches sur la Bonellie. Annal. des Sciences
nat. III Série. Tome X, pag. .r>3.
3 Graber. Sitzb. der Akad. der Wissenschaften. Wien. IteAbth.
Jan. Heft. Jahrgang 1873.
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