XXVII] SKIN. SENSORY NERVE ENDINGS 213 



of the epidermis the fibrils will probably be represented by a 

 series of small globules corresponding to the varicosities ; in the 

 centre of the bundle are two or three larger fibrils having a 

 zigzag course. 



The slightly conical mass of modified epithelium cells ex- 

 tending from the surface, around and in which the nerve fibrils 

 run. 



A few fibrils run to the surrounding ordinary epidermic cells. 

 A small end-bulb may be present immediately beneath the epi- 

 dermis where the nerves lose their medulla. 



(6) Note in the transverse section 



The circular areas of the columns of modified epithelium 

 cells ; the ring of nerve fibrils around each, and the two or three 

 . fibres in the centre. 



DEMONSTRATIONS. 



1. Vertical section of scalp, or other skin containing 

 hairs (osmic acid). Note the fatty globules in the 

 sebaceous glands. 



2. Vertical section of tip of finger (osmic acid). 

 Note the medullated fibre entering a touch corpuscle. 



3. Section stained with orcein to show the elastic 

 fibres. 



4. Section of skin of face of rat or cat cut nearly 

 in the plane of the surface, but a little obliquely 

 (alcohol, picrocarmine). Observe one of the large 

 tactile hairs with its cuticle, and the sheaths of its 

 follicle (cp. 1, d). In the sections of the roots, note 

 the ring of transversely cut nerve fibres outside the 

 hyaline membrane, 



