IV 



THE SENSE OF SMELL 



163 



extended over a part of the middle turbinal (Schwalbe), because 

 the yellow portion above described is more extensive than the 

 olfactory epithelium proper, and covers, particularly in the foetus 

 and new-born animal, a certain portion of the middle turbinal as 

 well. But the work of Max Schultze and the measurements of 

 von Brunn showed that the region innervated by the olfactory 

 nerve is confined in adults to a portion of the upper turbinal and 

 of the septum. Von Brunn carried out his investigations on two 

 adult subjects, aged from thirty to forty. He made sections of the 

 nasal mucous membrane, and was thus able to determine the true 

 extension of the olfactory epithelium. In the first subject the 



3 9 



FIG. 64. Nerves of outer wall of nasal cavity. -?. (Sappey, from Hirschfeld and Leveille.) 

 1, network of branches of olfactory nerve descending into the region of the upper and middle 

 turbinals ; 2, external branch of nasal nerve ; 3, spheno-palatine ganglion ; 4, ramifications of 

 great palatine nerve ; 5, small palatine nerve ; 6, external palatine nerve ; 7, branch to region 

 of lower turbinal ; 8, branch to region of upper and middle turbinals ; 9, naso-palatine branch 

 to septum (divided). 



olfactory region of the right side measured 238 sq. mm., in the 

 second 257 sq. mm. So that the dimensions of this area are com- 

 paratively restricted, as it only amounts to about 5 sq. cm. for 

 both nostrils. 



In the olfactory region two different kinds of epithelial cells 

 were described by Eckhardt in the frog (1855), and by Ecker in 

 man and in certain mammals (1856). M. Schultze (1863) distin- 

 guished them as olfactory cells and columnar epithelial cells. The 

 former are true peripheral nerve cells, which are directly con- 

 tinuous with the fibres of the olfactory nerve ; the second are 

 merely special supporting cells (Fig. 65). This distinction, 

 which Exner at first disputed, was subsequently confirmed by the 



|>lgi method. 

 The peripheral end of each olfactory cell is continued into a 



