§ 172. 
THE ACEPHALA. 
189 
of this order, the mantle receives, moreover, numerous blood-vessels, or 
ramified prolongations of the body of the animal. 
These last are spherical or star-like, with Salpa 
maxima, and dendritic with Salpa bicaudata ; 
with these species they are not soluble in hydro- 
chloric acid, and are therefore probably composed 
of silex. In the mantle of Botryllus, there are, 
in certain places, peculiar flexuous fibres running 
in all directions, If these are treated with potassa 
*hey will appear evidently composed of cellulose. 
According to Kélliker, the structure of the man- 
tle of Cynthia papillata is still more complicated. 
Its middle layer is composed of longitudinal and 
circular flexuous non-azotized fibres. Between 
these lie granules, nuclei, crystals and cells ; these 
cells are nucleated, and contain, sometimes pigment 
granules, and sometimes daughter-cells which gives 
them the appearance of those of cartilage. 
Kéllixer was unable to determine the structure 
of the th rd and external layer which is horny, for 
he had at his disposal only alcoholic speci 
of this Cynthia. He saw however that it united 
with the middle layer to form the spines which pro- 
ject from the surface of the skin... 
In the mantle of Cynthia pomaria, the longitu- 
dinal fibres predominate, and between them lie 
crystals, round pigment-cells, and other cells which 
* [§ 172, note 4.] The presence of cellulose in 
animal tissues is a fact of no inconsiderable import- 
ance in animal and vegetable physiology. The 
subject has recently received much attention from 
Schacht (Miller’s Arch. 1851, p. 176), and his. 
conclusions are sufficiently interesting to be pre- 
sented in full. ' 
‘1, In the mantle of the Ascidiae there is'a 
are peculiar and filled with yellow corpuscles ; and 
finally, a third variety arising from the transform= 
ation of the pigment-cells, whose walls are gradu- 
ally thickened and ultimately split up into fila- 
ments, forming concentric layers around the cell- 
cavity. When subjected to potassa, these cell- 
membranes are decomposed, like the principal 
fibres, into an insoluble, non-azotized substance, 
while all the other elements of the mantle entirely 
disappear under the action of this agent. 
The researches of Kélliker and Léwig up- 
on the mantle of the Tunicata, have been re- 
cently published in the Ann. d. Sc. Nat. V. 1846, 
p. 193, Pl. V.-VIL* 
5 Blood-vessels are found in the mantle of vari- 
ous Phallusiae ; they are spread out in a reticu- 
lated manner, especially in the external layer. 
‘See Cuvier, Mém. sur les Ascidiés, &c., p. 16, Pl. 
Ill. fig. 1 (Phallusia mamillaris); Savigny, 
Mém. &c. p. 102, Pl. IX. fig. 1. B. (Phallusia 
sulcata); and Delle Chiaje, Descrizione e noto- 
mia degli animali invertebrati della Sicilia citeriore 
Tom. III. 1841, p. 33, Tay. LXX XIV. fig. 2 (Phal- 
lusia monachus). ~ 
lose, covers the inner surface of the three Ascidiae 
which I examined ; the outer surface of the man- 
tle of Phallusia appears to have a similar epithe- 
lium. 
“6, There are two essential points of difference 
between the modes in which cellulose occurs in the 
Ascidiae'and in the vegetable kingdom : 
“(1.) In Phallusia, the cellulose constitutes the 
in potass, but soluble in 
inter-cellula , but does not, as in plants- 
sulphuric acid, which is turned to a beautiful blue 
by iodine and sulphuric acid, and which therefore 
consists entirely of cellulose. This substance con- 
stitutes the interstitial substance of the cells ; in 
the mantle of Phallusia it is homogeneous, but in 
Cynthia it occurs for the most part in a fibrous 
form. 
“2, The mantle of the Ascidiae contains beside 
this cellulose, another material which is soluble in 
caustic potass, but insoluble in sulphuric acid, and 
not colored blue by iodine and sulphuric acid, and 
which consequently is not cellulose ; in the mantle 
of Phallusia it is only sparingly. present, but in 
Cynthia and the new Chilian Ascidian, it is much 
more abundant and alone constitutes the corneous 
epidermis of their mantle. 
“©3. The membrane of the cells in the mantle of 
Phallusia does not consist of cellulose, it is colored 
brown by iodine and sulphuric acid ; it is soluble 
in caustic potass, and behaves exactly like an ani- 
mal membrane as do the nuclei and vessels. 
“4, In the mantle of Phallusia, cells abound in 
a homogeneous, interstitial substance composed of 
cellulose ; it is only at the inner margin of the mantle 
that fibres composed of cellulose, with nuclei among 
them, make their appearance. In Cynthia, &c., 
there are scarcely any traces of cells, while the 
nuclei and cellulose fibres abound. 
“6, A tessellated epithelium, no cellu- 
form an integral part of the cell-wall itself. 
“(2.) In Cynthia and other species, the cellulose 
forms free fibres, a form in which it is never ob- 
served in the vegetable kingdom. 
“7, The substance of the mantle of the Ascidiae 
is not disintegrated by boiling with caustic potass 
and nitric acid, like the vegetable cellular tissuc, 
into its elementary parts ; there is in it none of the 
inter-cellular substance universally present in veg 
etable tissues, and by which the cells are connected 
but which inter-cellular material is never composed 
of cellulose, as it resists sulphuric acid, but is solu- 
ble in caustic potass, as well as by maceration ; ” 
see loc. cit. p. 197, 198. This valuable paper is 
accompanied with three colored plates representing 
sections, &c., of the mantle-tissues, drawn by the 
camera lucida. 
From this it is clear that this discovery of cellu- 
lose in animals is very far from confounding the 
animal and vegetable kingdoms, for whatever else 
may be said, the previously established law that 
the animal cell-membrane always contains nitrogen, 
retains its force. 
See, also, the report of Payen on Kélliker and 
Léwig’s paper, before the Institute, in the Compt. 
Rend. 1846, XXII. p. 581. 
But see for some dissenting views on this subject, 
Huzley (Quarterly Jour. of Microscop. Sc. No. 
1, Oct. 1852, p. 22). — Ep. 
