CUTANEOUS NERVE-ENDINGS. 537 



Many different shapes and varieties of these bodies have been 

 described, but there seem to be no very definite morphological or 

 physiological distinctions between the different varieties. 



3. Touch-cells (Merkel) are found in the deeper layers of the 

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

 cells with distinct nuclei and nucleoli. Frequently they are 



FIG. 209. FIG. 210. 



I 

 a 



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 tac- 

 tile cells, between which lies the tactile disk. (Izquierdo.) 



grouped together in masses and surrounded by a kind of sheath 

 of connective tissue ; in which condition they resemble touch-cor- 

 puscles. 



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 soft cells 

 of the mucous layer, either in branched cell-like bodies (Langer- 

 haus), 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, com- 

 monly called 



45 



