TOUCH, TEMPERATURE, MUSCULAR SENSE. 493 



on a relatively blunt end only slightly raised above the gen- 

 eral epithelial level. 



As in the case of taste, so here there is absolutely no 

 knowledge at present as to the exact manner in which the 

 sensations of smell are produced. Possibly here, too, the 

 subjective element plays a very important part, for it not 

 infrequently happens that a person who has experienced an 

 exceedingly unpleasant odor (such, for instance, as those 

 associated with a corpse) will have this odor recur after 

 that from time to time with the clearest exactness, although 

 every possibility of the offending gases actually having af- 

 fected the nose was precluded. Smell sensations are oc- 

 casioned by the introduction of gaseous substances only, 

 but the intensity of the sensation depends not only upon 

 the strength of the gas, but also upon the circumstance that 

 this gas must stream through the nose. A gas allowed to 

 rest in the nose soon ceases to affect the membrane. For 

 this reason the air is always sniffed when the odor of any- 

 thing is to be detected. 



One of the most remarkable things about the sense of 

 smell is that it may be aroused by almost inconceivably 

 small quantities of odorous matter. Musk, for instance, 

 may fill large spaces with its odor and do so for relatively 

 long times, and yet not lose measurably in weight. 



A further interesting fact is the inability we have of 

 forming anything like a scale of odors, or even our inability 

 to divide them into related groups. In fact, we are unable 

 to designate them with definite names, but apply to them 

 the names of the objects in which they occur. We are also 

 further entirely unable to analyze odors into their compo- 

 nents, a thing which can be easily done in the matter of 

 colors with the eye, or still more easily with sounds in the 

 ear. Even when one nostril is filled with an odor of one 

 kind and the other nostril with a different odor, the two 

 sensations do not blend at all, but we perceive now the one, 

 now the other, depending upon the relative strength or sen- 

 sitiveness of the two nostrils. 



