516 HORN. 



a medulla or pith, composed of soft spherical or polyheclra 

 cells, and of a cortical portion, which has a fibrous appear- 

 ance, due to elongated fusiform cells, like the cortical por- 

 tion of the hair. The thickness of the fibres varies; those at 

 the surface of the wall of a horse's hoof are the smallest and 



Fie "IS fCHATJVEAU.) Transverse section of several horn fibres of the horse s sole, 

 showing the concentric arrangement of scales around a central medulla; also the super, 

 imposed cells constituting the agglutinating material, X 100. 



most compact. Between these fibres there is an intermediate 

 substance, best seen on examining a transverse section of 

 horn. Such x a section (fig. 218), when examined by trans- 

 mitted light, affords us a view of the concentric layers of 

 horn-cells surrounding the soft opaque medulla, besides the 

 connecting substance formed by a dense mass of cells similar 

 to those which constitute the fibres, but disposed in an oppo- 



