ANATOMY OF THE OLFACTORY ORGAN 



27 



ous branched alveolo-tubular glands which, contain both 

 mucous and serous cells. 



The conchsB of the respiratory region have long been 

 known to be extremely vascular and to be possessed of a 

 structure like that of erectile tissue. This is especially 

 true of their edges. They can be 

 excited through reflex channels to 

 considerable enlargement and the 

 swelling thus produced may be suffi- 

 cient to close completely the respir- 

 atory passages. It is believed that 

 this high vascularity of the respira- 

 tory region is concerned with the 

 moistening and warming of the 

 current of respiratory air. The 

 secretions of this portion of the nose 

 are also believed to be inimical to 

 pathogenic germs and thus to afford 

 a protection to the deeper parts against the invasion 

 of disease. 



The olfactory region in man is yellowish in color as 

 it is in the calf and in the sheep. In the dog and the 

 rabbit it is of a more brownish hue. According to the 

 older anatomists it was supposed to extend in man over the 

 dorsal half or even more of the nasal cavity. Von Brunn 

 ( 1892 ) , however, claimed by a reconstruction from sections 

 that the olfactory epithelium was much more restricted 

 than had been originally supposed. According to this 

 author only a small portion of the superior concha and a 

 correspondingly small part of the nasal septum represent 

 the unilateral area of distribution of the olfactory nerve. 

 This area in one subject measured 257 sq. mm. and in an- 



FlG. 3. — Respiratory epi- 

 thelium from the nasal cavity 

 of a young pig; b, basal cell; 

 c, ciliated cell. After Alcock, 

 1910, Fig. 2. 



