86 SMELL, TASTE, ALLIED SENSES 



It is needless to say that since in this form of double 

 stimulation one stimulus is applied to one olfactory organ 

 and the other to the other organ, the phenomenon of neu- 

 tralization cannot depend upon the chemical action of 

 one odor upon the other, for the odorous materials are 

 not allowed to mingle. The fact that they are separately 

 applied to different receptors shows that this type of 

 conflict and of neutralization must have a central origin. 



10. Olfactory Reflexes. In discussing the relations 

 of the two categories of nasal stimuli, irritants and true 

 odors, Frohlich attributed reflex action to the first but 

 not to the second, and it is true that nasal irritants 

 almost invariably call forth vigorous respiratory re- 

 sponses, such as sneezing, whereas true odors are seldom 

 followed by reactions of a marked kind. Pawlow, how- 

 ever, has pointed out the great importance of true odors 

 in exciting and, in a way, in controlling the whole chain 

 of digestive secretions, a process just as significantly 

 reflex as sneezing but not so easily observed. Both 

 classes of stimuli, then, are followed by abundant and 

 important reflexes, but in one class these are of a kind 

 easily noticed, in the other they are more hidden. 



Although the olfactory organs in man are unques- 

 tionably concerned with the odors of the food that is 

 being masticated, they are much more concerned with 

 the odors of the environment. From this standpoint the 

 olfactory organs are properly classed as distance-recep- 

 tors or receptors affected by stimuli that emanate from 

 more remote points in the surroundings. In consequence 

 our olfactory sensations are in a way projected into the 

 exterior and we seek, avoid, or recognize the distant body 

 by its odor. The smell of a skunk is unquestionably a 



