578 Speeielle Morphologie. 
living and also in preserved specimens these heads may be stretched away from each other, 
but each remains attached to its neighbours by more or less regular anastomoses. It thus 
is brought about that the surface of the skin is made up of a sort of honeycomb of tissue, 
each of the nodes being the outer end of an ectoderm cell. The cells are very difficult to 
separate finely 
—. On separation each cell is very thin; its outer end is slightly pyra- 
midal, and is continued into a thin fibre which gives off anastomoses with adjacent cells and 
dilates at intervals.. In one of these dilatations, generally the last [?], the nucleus is placed. 
Below this point the cell is continued into a very fine filament which may be traced for 
some distance«. Ferner: »In sections of hardened specimens these filaments may be followed 
into the layer of nerve-fibre, which is always more or less developed at the base of the ecto- 
derm cells over the whole body. These cells compose the larger part of the skin of the 
proboscis and collar. Among them are distributed cells which probably secrete mucus, etc. 
These cells are of several kinds. First, in the skin of the proboseis are large goblet cells 
whose nucleus alone stains. Next, in the skin of the back of the collar and of nearly all 
the rest of the body excepting those parts in which concentrations of nervous tissue are found, 
almost the whole tissue is made up of large cells full of some substance probably lubricating 
also, which does not stain. In parts of the skin which are of this kind the large cells of the 
ectoderm are comparatively few in number, and thus the skin has a spongy consistencey which 
is very characteristic. This is true of the skin behind the collar in B. minutus, B. salmoneus 
[= Pt. sarniensis|, and B. robinü [= Pt. clavigeral. There is a general similarity between 
the skins of all these forms, and probably their structure is the same as in B. robinü, — — 
In the skin of the collar and proboscis especially a small number of nuclei may be seen in 
the higher layers of the skin. Whether these belong to young cells of the tailed series or 
of the secreting type was not determined. Another set of small, generally bifid secreting 
cells, are found in the proboscis skin; the contents of these cells are granular.«e — — »The 
skin of BD. kowalevskü differs in some ways from that of B. minutus etc., especially that of 
the trunk, in which the large goblet cells are comparatively rare. In all parts of the skin 
round, unicellular glands are more or less frequent, but their contents stain more or less 
deeply with hamatoxylin, etc. 'These cells often fall out, leaving empty spaces. In the collar 
of B. kowalevskü the skin is very thick and is full of very long cells containing granular 
contents, which stain very deeply«. 
Auch bei Marıon (1886 p. 310) finden wir einige Angaben über die Structur der 
Epidermis. Bei Gl. hacksi »les el&ments cellulaires de cet hypoderme ont pris en effet la 
disposition fibrillaire au point que les limites des cellules ne sont pas apparentes«. Von @l. 
talaboti bemerkt er (p.321): »L/’hypoderme possede de plus cette particularit@ remarquable que 
les cellules glandulaires y sont tres abondantes et tres volumineuses. Elles apparaissent comme 
de grosses vesicules hyalines, placdes cöte A cöte A la peripherie de lectoderme et se prolon- 
geant par un pied fibrillaire, de maniere A reproduire l’aspect que l’on trouve dans l’hypo- 
derme glandulaire de divers actiniaires — — (fig. B)«. 
