306 MICROSCOPIC ANATOMY OF THE ORGANS. 



to the deeper layers, where they end freely (Retzius). The 

 ends of the fibres often show knob-like thickenings. Varia- 

 tions in thickness in the course of the fibre, the so-called 

 varicositieSy are, on the contrary, due to methods of preparation 

 or to post-mortem changes. 



Among the intra-epithelial nerve-endings must also be con- 

 sidered those of the glands. As investigations of late years 

 have shown, the nerve fibres end on the surface of the gland 

 cell, and never enter into it, as formerly was supposed. Often 

 the terminations of fibres on the cell surface are thickened and 

 flattened. 



Also we find in the epithelium nerve-endings in the form 

 of end corpuscles, the so-called MerkeVs corpuscles (Figs. 227, 

 228, 229). These are found most numerously in the pig's 



FIG. 228. 



Cells of 

 epidermis 



Merl-eVs 

 'tctile cells 



From a vertical section through the skin of a pig's snout. In the corium three medullatcd 

 nerve cells run upward ; on the epidermis lie many tactile corpuscles of Merkel. X 450. 



snout and in the outer root sheath of tactile hairs. In the 

 deepest layer of the epidermis we find cells which are distin- 

 guished from other epithelial cells by their greater size and 

 clearness, and by their large vesicular nuclei. By means of 



