CHAPTER XVIII 

 THE SPECIAL SENSES 



602. In the special senses sight, hearing, smell, taste, 

 touch (including the temperature sense) we refer the 

 sensations to some external cause, but general sensations 

 (fatigue, pain, hunger), as previously stated, are referred 

 to our own bodies. You learned that the muscular sense 

 is made up of special sensations of touch and general 

 sensations from the muscles. Hence the much discussed 

 question as to whether the muscular sense is a sixth special 

 sense, is best answered by classing it with the general 

 sense. The special sense of touch has been studied in a 

 previous chapter. 



603. The Sense of Taste (Fig. 165). It was mentioned 

 that the tip of the tongue has a very keen sense of touch. 

 The tongue is a very muscular organ, and when we are eat- 

 ing, it helps to keep the food between the teeth ; it also does 

 the chief part of the work in the beginning of the process 

 of swallowing. But perhaps its most important function is 

 to afford a home for the nerves of taste. These nerves 

 consist of a branch of the fifth pair of nerves, which are 

 distributed over the front part of the tongue, and the ninth 

 pair, which go to the back part of the tongue (Fig. 201). 

 Although we often speak of food as being palatable, the 

 sense of taste in the palate is very feebly developed. 



604. What we call flavors affect us through the sense 

 of smell. If the nose be closed with the hand, a piece of 

 onion placed on the tongue does not have the " taste " of 

 onion at first, nor at all, unless particles are wafted up and 



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