CUTANEOUS NERVE ENDINGS. 



539 



epidermis of man as well as in the tongues of birds ; they are 

 large cells with distinct nuclei and nucleoli. Frequently they 

 are grouped together in masses and surrounded by a kind of 

 sheath of connective tissue, in which condition they resemble 

 touch corpuscles. 



4. Free nerve endings occur on the surface of the epithelium of 

 the mucous membranes, and are seen on the surface of the cornea. 

 Here delicate, single strands of nerve fibrils can be seen after gold 

 staining, passing between the epithelial cells and ending at the 

 surface in very minute blunted points or knobs. 



Naked nerve fibrils have also been traced into the deeper 

 layers of the epidermis of the skin, where they end among the 



FIG. 209. 



FIG. 210. 



FIG. 209. End bulb from human conjunctiva, treated with osmic acid, showing cells 

 of core. (Longworth.) a, Nerve fibre; 6, nucleus of sheath; c, nerve fibre within core; 

 d, cells of core. 



FIG. 210. Tactile Corpuscle from the Duck's Tongue, containing two tactile cells, 

 between which lies the tactile disk. (Izquierdo.) 



soft cells of the mucous layer, either in branched cell-like bodies 

 (Laugerhans) or delicate loops (Ranvier). 



In the subcutaneous fat tissue as well as in parts remote from 

 the surface are large bodies, easily visible to the naked eye, 

 commonly called 



5. Pacinian Corpuscles. They are ovoid bodies made up of a 

 great number of concentrically arranged layers of material, of 

 varying consistence, with a collection of fluid in the centre in 

 which an axis cylinder ends. There is no doubt that they are 

 the terminals of afferent nerves, but if they belong to the sense 

 of touch, which is doubtful, it is unknown to what special form 



