694 THE SENSES 



been discovered in the case of tastes. In the art of cooking, however, atten- 

 tion has at all times been paid to the consonance or harmony of flavors in 

 their combination or order of succession, just as in painting and music the 

 fundamental principles of harmony have been employed empirically while 

 the theoretical laws were unknown. 



Frequent and continued repetitions of the same taste render the perception 

 of it less and less distinct, in the same way that a color becomes more and 

 more dull and indistinct the longer the eye is fixed upon it. There is fatigue 

 of the taste organ at some point. 



THE SENSE OF SMELL. 



The sensation of smell is produced by the action of odorous particles on a 

 special end-apparatus, which in turn causes nerve impulses that arouse 

 changes in a special area in the sensorium. The stimulating cause is the 

 direct action of chemical substances as in the sense of taste. In this case 



FIG. 426. Nerves of the Septum Nasi, Seen from the Right Side. X f. /, The 

 olfactory bulb; i, the olfactory nerves passing through the foramina of the cribriform plate, 

 and descending to be distributed on the septum; 2, the internal or septal twig of the nasal 

 branch of the ophthalmic nerve; 3, naso-palatine nerves. (From Sappey, after Hirschfeld 

 and Leveille.) 



however, the substances must reach the sensory membrane in a gaseous 

 state or in extremely fine division, so that it can quickly enter into solution 

 in the moisture on the sensitive mucous surface. The odorous particles are 

 carried to the membrane by inspiratory currents of air. 



The Olfactory Apparatus. The essential parts of the olfactory ap- 

 paratus are the nasal sensory or olfactory membrane to receive the special 

 stimuli, and the nervous apparatus to conduct the olfactory nerve-impulse to 

 the sensory area in the cortex cerebri for its perception. 



