ii4 ELEMENTS OF HISTOLOGY. [Chap. xiv. 



they form by association simple axis cylinders, which 

 vary in thickness according to the number of their 

 constituent primitive fibrils. These simple axis cylin- 



Fig. 70.- Intra-epithelial Nerve-termination in the Anterior Epithelium 

 of the Cornea, as seen in an oblique section. 



a, An axis cylinder; 6, sub-epithelial nerve-flbrillae ; c, intra-epithelial network; 

 d, epithelial cells. (Handbook.) 



ders form plexuses. By association they make larger 

 axis cylinders, and these becoming invested with a 

 neurilemma, and with the nuclei of nerve corpuscles, 

 form non-medullated nerve-fibres. These also form 

 plexuses. Lastly, a medullary sheath makes its ap- 

 pearance between the neurilemma and the axis 

 cylinder, and thus forms a medullated 'nerve-fibre. 



