XXV.] TASTE AND SMELL. 259 



6. In the olfactory part of the raucous mem- 

 brane, the division of the epithelium into an 

 outer and an inner layer. 



a. The outer layer consisting of the peri- 

 pheral processes of both cylindrical and 

 rod-cells. 



/3. The inner or nuclear layer consisting 

 of several rows of nuclei belonging to 

 the rod-cells. The nuclei of the cylin- 

 drical cells form a single row in the 

 upper part of this layer, but these, as 

 well as the greater part of the processes 

 of the rod-cells, are generally hidden by 

 the nuclei of the rod-cells. 



7. In the sub-mucous tissue the numerous 

 bundles of the non-medullated nerve- 

 fibres of the olfactory nerve. Near the 

 epithelium these form a close-meshed 

 plexus. 



S. Serous glands, usually tubular with a 

 few branches; here and there a duct 

 may be seen running through the epi- 

 thelial layer as a fine tube consisting 

 of basement membrane and flattened 

 cells. 



3. From a rabbit's tongue which has been hardened 

 in chromic acid *2 p.c., or in potassium bichro- 

 mate 1 p.c., excise a papilla foliata (cp. p. 32, 

 29) and imbed in such a way that the sections 

 will be at right angles to the ridges. 



17-2 



