SVENSKA EXPEDITIONEN TILL MAGELLANSLÄNDERNA BD II N:0 4. 57 



enough not so well preserved as to allow a detailed histological 

 research. ßut all the same, the main points of the structure 

 may very plainly be discerned. For that reason I have made 

 transverse and tangential sections through a piece cnt out 

 from the surface of the mantle. By studying the transverse 

 seetions (PI. V Fig. 1) we find, if progressing from the inner 

 layers towards the surface, the following. The central parts 

 of the mantle are constituted by the dense and powerful 

 layers of transverse muscnlature (c m) which here and there 

 is pierced through by bunches of muscular fibres which extend 

 in a radial direction. Outside of this thick coat of circular 

 or transverse muscles we meet the comparatively thin layer 

 of longitudinal muscles (1 m) which are cut off on these sec- 

 tions. All the muscles imbibe eosin in a high degree and 

 show the long and linear nuclei stained blue by huematox^din 

 On top of the longitudinal muscles we find a layer of connec- 

 tive tissue (c t) of about the same thickness. It is made 

 up of fibrils stretching themselves in various directions and 

 constituting a rather dense network in which a great number 

 of cell-corpuscles and nuclei are situated. This layer is also 

 richly furnished with bloodvessels for the nutrition of the 

 dermal layers. On the surface of this tissue the papillär (p) 

 are situated. They rise on a broad base with steep sides and 

 have a Hat surface. Their dimensions vary a good deal and 

 the shape is rather irregulär, some of the larger measuring 

 as much as 5 mm. in diameter, but others are smaller 

 2 V 2 — 3 mm. the mean measurement may, however, be about 

 4 mm. The height is about 1 mm. or a little more. The 

 papillär are, as can be seen on the sections, very well defined 

 from the surrounding tissues by a very dense, althongh com- 

 paratively thin Stratum composed of elastic fibrils and fibrils 

 of connective tissue. Within this Stratum limitans which 

 makes the papilla a solid body by itself and fixes it to the 

 underlying subcutaneous layer, is a tissue of peculiar structure 

 which constitutes the main mass of the papilla. On the 

 transverse sections it looks like a network with very large 

 irregularly elliptical meshes which are tangentially extended. 

 On a tangential section through a papilla the meshes are 

 rounder (Fig. 2). The rooms in this network are occupied by 

 cellules of »grossblasige Bindegewebe», but the network itself 

 is built up of thin and long, wavy, elastic fibrils which are 



