ORGANS OP TASTE. 205 



smell are much less vitiated, than in civilized man ; and 

 hence the men of the forest, it is said, are guided, in a 

 considerable degree by these senses, in the choice of 

 their food, especially in times of scarcity, when they are 

 obliged to roam in search of new articles. 



ORGANS OF TOUCH. 



By the sense of touch we are enabled to know the 

 external properties of bodies. 



Physiologists make a distinction between tact and 

 touch. Tact, with some few exceptions, is generally dif- 

 fused through all our organs, and particularly over the 

 skin. It exists in all animals, while touch exists chiefly 

 in the fingers of man, in the antennce of insects, and in 

 the noses of certain quadrupeds. 



In the exercise of these functions, tact is considered 

 passive, as when any part of the system comes into con- 

 tact with another body, a sensation of its presence is 

 given, without the exercise of volition. On the coittrary 

 touch is active, and is exercised voluntarily for the pur- 

 pose of conveying to the mind a knowledge of the 

 qualities, or properties of the surfaces of bodies ; as 

 when we feel a piece of cloth to ascertain its quality, 

 or a polished surface to prove its smoothness. 



Anatomy of the Skin. The sensation of tact, and 

 touch is conveyed to the brain by means of nerves situ- 

 ated in the skin. 



The skin consists of three parts called the cuticle, or 

 epidermis ;'the rete mucosum ; and the corium, or cutis 

 vera, or true skin. 



The cuticle is the external layer. In its structure it is 

 membranous and dry, having neither nerves, veins, nor 

 arteries. It has therefore no sensation, its office being 

 merely to protect the true skin from external injury. 

 The cuticle is that thin membrane which is raised by a 



What is the difference between touch and tact 1 In the exercise of these 

 functions which is active and which passive 7 How are these sensations 

 conveyed to the brain 7 What parts compose the skin, and what their 

 names 1 What is the cuticle and where is it situated ? What is the use 

 of the cuticle ? 



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