218 PRACTICAL HISTOLOGY [XXVIII 



Observe (h. p.) 



The outer layer of the olfactory epithelium, with- 

 out nuclei, and appearing as very closely packed thin cell 

 bodies or processes (the outer portions of the columnar 

 and of the olfactory cells). 



The inner layer, in which little is seen but closely 

 packed nuclei ; the outermost layer of nuclei (belong- 

 ing to the columnar cells) are elongated ; the rest are 

 round or nearly so (nuclei of the olfactory cells). 



The delicate processes of the olfactory cells project- 

 ing on the surface. 



The bundles of non-medullated fibres of the olfactory 

 nerve, and the small serous glands in the submucous 

 tissue. Here and there a duct may be seen running 

 through the epithelium, as a fine tube consisting of 

 basement membrane and flattened cells. 



The respiratory epithelium, consisting of columnar 

 ciliated cells and mucous cells. (This will probably be 

 seen in the lateral part of the nasal cavity. It is the 

 sole epithelium at the nasal openings.) 



2. Take a pithed frog or newt, cut off the upper 

 part of the head just in front of the eyes, from this 

 cut off the tip a little behind the nostrils. Examine 

 the piece with a lens and observe the nasal cavities, 

 cut away the roof of one nasal cavity, place in osmic 

 acid '5 p.c. for about \ an hour, wash well with water, 

 place in picrocarmine for 1 to 24 hours (better the 

 longer time), wash, scrape off a little of the olfactory 

 mucous membrane, tease and mount in dilute glycerine. 

 Observe 



The columnar or supporting cell; it has a 



