70 



PSYCHOBIOLOGY 



layer of compact circular bundles, and a thin inner layer, called the 

 glassy layer (hyaline membrane or vitreous membrane). 



The nerve fibre or fibres entering a follicle penetrate at about the 

 median level to the glassy layer, where each forms two branches which 

 almost completely encircle the hair, and on the opposite side arborize 



w 



Fig. 58. Nerve endings about a large hair of a dog. (Barker, Nervous System, 

 after Bonnet.) 



[Fig. 58], The nerve terminals very rarely penetrate through the glassy 

 layer. 



Since hairs are present over the entire body except the palms of the 

 hands, the soles of the feet, the dorsal surface of the terminal segments of 

 the fingers and toes, and certain parts of the genital organs, it is apparent 

 that they constitute an important group of receptor organs. 



AFFERENT NEURONS OF THE OLFACTORY MEMBRANE. 



The cell bodies of the olfactory afferent neurons are in the olfactory 

 epithelium. Outwardly, the cell has a short slender process (correspond- 

 ing to a dendrite) ending in a hemispherical knob that projects slightly 



