den udvendige Flade af deres bagerste Forlængelse, ved 
stærke tendinøse Baand. Disse Rør med deres mangfoldige 
Blærer vise i histologisk Henseende den samnie Bygning, 
som Tarmen; udvendig have de et flimrende Peritoneal- 
overtræk med sit Hpithel, saa et tyndt, fibrillært Binde- 
vævslag, hvortil Muskelhuden er bunden. Denne, der be- 
staar af langs- og tvergaaende Fibre, danner et rigt Maske- 
net, der var udfyldt af koaguleret ;Blodplasma: om dette 
indesluttes i en Karforgrening, der udfylder Maskenettet, 
eller det strømmer frit om i Lagene af Muskelhuden, kunne 
vi ikke afgjøre. 
Indenfor Muskellaget sees atter en Bindevævshud, i 
hvis indre Lag, som er det bredeste, og som bestaar af en 
hyalin, saagodtsom fiberfri Masse, findes saavel forgrenede 
Bindeyeevsceller, som de tidligere omtalte isolerede, aflange, 
klare Celler med kornet Indhold. Disse ere her tilstede 1 
temmelig stor Mængde. Men foruden de her nævnte Celler 
have vi iagttaget en Mangfoldighed af brunlige Legemer, 
som have en mere eller mmdre Kolbeform, og som skyder 
Epithelet foran sig, saa de beklædt af dette rage frem 1 
Rørets Lumen, Tab. I X, Fig. 38. Det er fornemmelig her 
de findes i stor Mængde, og de gruppere sig stundom saa- 
ledes, at de faa Udseende af Drueklaser. I Blærerne ere 
de sjeldnere og rage aldrig frem i dem, saaledes som i Rø- 
rets Hulhed. Man kan med Loupen iagttage dem som 
brunlige Punkter, der dels ligesom en Krands omgive Blæ- 
rernes Udspring, dels staa spredte rundtom baade paa Røret 
og Blærerne. Disse brune Legemer dannes af et Agelome- 
rat af branlige Molekiiler, uden at være omgivne af nogen 
Membran; de, have forskjellig Størrelse og synes at have 
noget tilfælles .med de Blodplasmaklumper, som vi have 
truffet paa baade i Tarmkanalens og Hudens Væv. De 
ere, saavidt vi have kunnet forfølge dem, ikke organiserede, 
og kunne visselig ikke betragtes som særegne functionelle 
Redskaber. 
Det indre Bindevævslag støder umiddelbart til det 
indre Epithel. Dette danner 1 selve Roret flere Lag Cy- 
linderceller, som .bidrage til at danne de stærkt fremstaaende 
paalangs gaaende Folder, der iagttages paa Rorenes indre 
Flade; i Blærerne er der neppe mere end et Lag Celler. 
De nu nylig beskrevne Lunger afvige i flere Punkter 
fra, hvad der hidtil er bekjendt om disse Organer hos Mol- 
padiderne og Aspidochiroterne. Hos disse er den ene 
Lungestamme uden Karforgrening og fri, imedens den anden 
følger Tarmen, er bunden til denne, og erholder en Kar- 
forgrening fra dens Rygkar; men begge tage de Udspring 
fra Kloaken. 
Hos Trochostoma er det helt anderledes. De ud- 
springe fra Tarmen (Kloak mangler, men en Rectum træder 
i dennes Sted); den venstre Stamme ligget tæt til Tarmens 
51 
and is webbed to the two dorsal radial segments of the cal- 
careous ring, viz. on the outer surface of their posterior 
prolation, by strong tendmous bands. These tubes with 
their numerous vesicles exhibit. the same histological struc- 
ture as the intestine; externally, they are invested with a 
vibratile peritoneal tunic and its epithelium, 
which is a thin fibrillous layer of connective 
webbed to the muscular integument. The latter, which is 
composed of longitudinal and transverse fibres, constitutes 
overlying 
tissue, 
an intricate network, having its meshes filled with coagula- 
ted sanguineous plasma; but whether this plasma be enclosed 
in a vascular ramification filling the meshes of the network, 
or whether it circulate freely through the layers of the 
muscular integument, is a question we are unable to decide. 
Beneath the muscular layer, too, extends a tunic of 
connective tissue, the inner and broadest layer of which, con- 
sisting of a hyaline, almost fibreless substance, contains alike 
ramose cells of connective tissue and the bright, elliptic-shaped, 
isolated cells previously described, which are comparatively 
numerous here. But, exclusive of the aboye-mentioned 
cells, we have observed great numbers of brownish, more or 
less claviform corpuscles, that, invested with the epithe- 
lium, which they push, as it were, before them, project up- 
wards into the lumen of the tube, Pl. IX, fig. 38. It is 
more particularly here that they occur in great num- 
bers, and so grouped as sometimes to assume the ap- 
pearance of clusters of grapes. In the vesicles, they are 
less numerous, and never project into them as they do into 
the hollow interior of the tube. Viewed under a lens, they 
appear like brownish points, some of which surround chaplet- 
like the origin of the vesicles; others le scattered round 
the tube and the yesicles. These brown corpuscles are 
composed of an agglomeration of brownish molecules, with- 
out however being enveloped in a membranous covering; 
they vary m size, and have apparently something in com- 
mon with the lumps of sanguineous plasma observed in the 
tissue of the intestinal canal and of the 
So far as our observations extend, they are not distinguished 
by an organic structure, and cannot therefore be regarded 
as having a special functional character. 
integument. 
The inner layer of connective tissue is connate with 
the inner epithelial layer. The latter forms in the tube 
itself several layers of cylindric cells, which contribute to 
the formation of the strong, projecting, longitudinal folds 
observed on the inner surface of the tubes; in the vesicles 
there can hardly be more than one layer of cells. 
-The respiratory organs described above differ in several 
respects from what is yet known concerning them im the 
Molpadide and the Aspidochirote. In these animals, 
one of the respiratory stems is free, and without a vascu- 
lar ramification; the other accompanies the intestine, to 
which it is attached, being furnished with a vascular 
ramification from its dorsal vessel; both however originate 
in the cloacum. 
In Trochostoma, quite another arrangement is observed. 
The tubes have their origin in the intestine (there is no 
cloacum, its place being supplied by a rectum); the left 
{7 
