PHYSIOLOGY OF OLFACTION 



75 



Henning, is represented by a number of odors, it is not ab- 

 solutely separated from the others, but between any pair 

 of them there are numerous odors that assume interme- 

 diate positions. The six classes, however, are the striking 

 predominant elements in this complex and are in no sense 

 submerged in the general array of odors. 



Henning has tried to make clear his idea of the rela- 

 tions of these six classes by imagining them located one 



flowery 



spicy 



fruity 



\ 



"S 



resinous 



FIQ. 17. Olfactory prism. After Henning, 1916, Fig. 4. 



at each corner of a three-sided prism which he calls the 

 olfactory prism (Fig. 17). From each corner of this 

 prism lines may be imagined to pass out to the other 

 corners ; these lines traverse either the edges of the prism 

 or pass over its faces and mark the positions of all in- 

 termediate odors. Thus all odors, be they fundamental 

 or intermediate, find places on the surface of the prism. 

 Relations indicated by lines within the prism and con- 

 necting any two points on its surface indicate only 

 mixed odors. Thus by means of a figure of three dimen- 

 sions Henning brings into clear view the relations 

 he conceives to exist between the six fundamental odors, 



