588 DBS. GEOBGE AND PRAJiJCES E. HOGGAli]' ON 



to any extent in tlie skins of large Mammals possessing papillse, 

 as the plexus fellows all the undulations in the dermic or epi- 

 dermic surface ; and consequently in a section parallel to the sur- 

 face of the skin, either the projections or the hollows would be 

 cut away, with the portions of the plexus lying there. We suc- 

 ceeded in showing it by stretching the skin of the smaller 

 Mammals, taken shortly after death, upon the histological rings 

 invented by us*, where it was shaved with a sharp scalpel to the 

 extent not merely of taking off all the hairs, but of taking off 

 also the epidermis, leaving at most only the cells belonging to 

 the lower layer still upon the dermis. 



To this shaved surface a 1-per-cent. solution of nitrate of 

 silver was momentarily applied, and the surface after some time 

 washed, and the images produced by the solution developed. A 

 similar solution of chloride of gold was then similarly applied, 

 and the surface afterwards washed, clarified with glycerine, and 

 mounted as a preparation. Figs. 28 & 29 are drawings of such 

 preparations, where the fine protoplasmic fibrils and cells, having 

 remained unaffected by the reagents, now appear as negative 

 images in the gelatinous field of the skin. At m a, meduUated 

 nerve is seen joining the plexus, of which the various groups 

 of cells represent the so-called terminal cells of Merkel. A 

 few of the outlines of the cells of the lower layer of epidermis, 

 e, have also been inserted, to show their relations to the plexus. 

 Where the fibrils appear to end, it only means that at that point 

 they either passed up into the epidermis and were cut off, or 

 that they passed downwards into the dermis beyond the reach of 

 the effects of the reagents employed. 



This plexus corresponds to the subepithelial plexus of nerve- 

 fibrils of the cornea, which has been so often described; but 

 the subepithelial layer of tissue there, being destitute of blood- 

 vessels, papillse, or large ganglion-cells, shows a much more 

 regular plexus than the skin of the trunk. Even in the smaller 

 Mammals the difference in the arrangements of the blood-vessels 

 causes considerable modifications in the appearance of the plexus. 

 Tims, for example, the skins of Moles and Eats possess a very 

 regular arrangement of meshes formed by blood-vessels of equal 

 calibre throughout, which lies immediately under the epidermis 

 in one general level, and the greater part of the subepidermic 

 plexus of cells and fibres runs alongside of the blood-vessels, 



* " Lymphatiques de la peau," in ' Journal de I'Anatomie,' January 1879. 



