SENSATIONS OF TASTE AND SMELL. 285 



ated in centimeters. It is evident that the further out the inner 

 tube is pulled the greater will be the amount of olfactory substance 

 which will be exposed to the incoming air of an inspiration. 



Conflict of Olfactory Sensations. When different odors are 

 inhaled simultaneously through the two nostrils they may give rise 

 to the phenomenon of a conflict of the olfactory fields similar to that 

 described for the visual fields. That is, we perceive first one then 

 the other without obtaining a fused or compound sensation. The 

 result depends largely on the odors selected. In some cases one 

 odor may predominate in consciousness to the entire suppression 

 of the other, a phenomenon which also has an analogy in binocular 

 sensations. It is well known, also, that certain odors antagonize or 

 neutralize others. It is said, for instance, that the odor of iodoform, 

 usually so persistent and so disagreeable, may be neutralized by the 

 addition of Peru balsam, and that the odor of carbolic acid may 

 destroy that of putrefactive processes. Whether the neutralization 

 is of a chemical nature or is physiological does not seem to have 

 been definitely ascertained. 



Olfactory Associations. Personal experience shows clearly 

 that olfactory sensations arouse numerous associations our 

 olfactory memories are good. On the anatomical side the cortical 

 center in the hippocampal lobe is known to be widely connected 

 with other parts of the cerebrum, and we have in this fact a basis for 

 the extensive associations connected with odors. In animals like 

 the dog, with highly developed olfactory organs, it is evident that 

 this sense must play a correspondingly large part in the psychical 

 life. In such animals as well as among the invertebrates it is in- 

 timately connected with the sexual reflexes, and some remnant of 

 this relationship is obvious among human beings. Among the so- 

 called special senses that of smell is perhaps the one most closely 

 connected with the bodily appetites, and overgratification or over- 

 indulgence of this sense, according to historical evidence, has at least 

 been associated with periods of marked decadence of virtue among 

 civilized nations. 



