78 SENSE OF TOUCH. 



4. These faculties or senses, in man and most animals aie rive 

 in number; namely : touvh, t<ist<>, sine//, hearing, and sight. 



5 Touch and taste are only exercised upon bodies which are 

 brought into contact with those organs which are the seat of 

 those senses. Smell, hearing, and sight, make us acquainted 

 with certain properties of objects at a greater or less distance 

 frvm us. 



6. All- animals do not possess the senses in an equal number 

 with man ; in some, there is neither organ of sight, nor organ of 

 hearing, nor organ of smell ; such is the oyster for example : in 

 others, one or another of these instruments is wanting. 



We will now consider each one of the senses, and the organs 

 which are the seat of them. 



OB^ THE SENSE OF TOUCH. 



7. Touch is the sense which reveals to us the contact of foreign 

 bodies with our organs and informs us of the nature of their sur- 

 faces whether rough or smooth, their movements, the degree of 

 their consistence, their temperature, and, to a certain extent, their 

 form, volume and weight. 



8. Tact is a passive touch, but this function sometimes becomes 

 active : it is more especially called touch, when the sensibility is 

 most exquisite and the surface, which is its seat, can in a manner 

 mould itself to objects. 



9. Tactile sensibility is spread out in all parts of the surface of 

 the body, and resides in the skin. 



1 0. The skin is the membrane which covers or clothes the 

 body. It is principally composed of two parts, one called the 

 corivm or derma, or true skin, the other, the epidermis or cuticle, or 

 scarf-skin. 



1 1. The epidermis is the most superficial layer of the skin; it 

 is a sort of thick varnish which covers the derma and serves to 

 protect it against the contact of hard bodies, and prevent it from 

 oecoming dry by the action of the air. 



12. The derma is the thickest and most important part of the 

 kin; it is beneath the epidermis, and adheres to the subjacent 



^ 4. What is the number of the senses? What are they called? 



5. What is necessary t;rthe exercise of the faculties of touch and taste? 

 What faculties convey to us notions of bodies withou' contact ? 



6. Have all animals the same number of senses as man? 



7. What is touch ? 



8. What is tact? When does it become touch? 



9. What is the seat of tactile *& sibility ? 



10. What is the skin ? Of what pans is it composed? 



11. What is the epidermis ? What is the use of the epidermis or cuticle ? 



12. What is the derma ? Where is it placed ? Has 'he derma anv nerves? 

 What fbrwi the napilliE of the derma ? Where is the derma most sensible ? 



