32 SMELL, TASTE, ALLIED SENSES 



from five to eight. Because of their great delicacy the ol- 

 factory hairs are probably seldom observed to their full 

 length. Schultze (1856) described those of the frog as 

 long, but Jagodowski (1901) has shown 

 that in the pike the hair may be twice as 

 long as the olfactory cell itself, (Fig. 9) 

 and may reach from the distal end of the 

 cell through the whole thickness of the 

 superimposed slime. So delicate are the 

 distal portions of these hairs that 

 Jagodowski has proposed for them the 

 name of olfactory flagella or lashes. In 

 the opinion of this author the so-called 

 olf actorj' hairs are only the proximal ends 

 of these lashes, the distal part having 

 disappeared in the course of preparation. 

 The lashes can be demonstrated by means 

 of the Golgi method or by osmic acid. 

 These lashes are without doubt the true 

 receptive elements of the olfactory cells. 

 The secretion in which they are suspended 

 and whose thickness they probably 

 penetrate is produced by the numerous 

 Fio. 8— laoiatcd olfactory or Bowman glands whose ducts 

 BMte'iTtecular cdi Open out abundantly through the olfac- 



from a frog. After . * j i i • 



Schultze, 1862, torv epithelium. 



Plate 1, Fig. 4. .' i 



4. Intermediate Zone. In the majority 

 of vertebrates there seems to be a fairly sharp boundary 

 between the respiratory epithelium and the olfactory 

 epithelium. In some mammals, however, these two regions 

 are separated by a considerable intervening area, known 

 as the intermediate zone. This was first described by 



