[Illustration:  INSIDE OF THE NOSE.]

25. Smelling is a sort of feeling.  The nerves of smell are so sensitive that they can discover things in the air which we cannot taste or see.  An Indian uses his sense of smell to tell him whether things are good to eat or not.  He knows that things which have a pleasant smell are likely to be good for him and not likely to make him sick.

We do not make so much use of the sense of smell as do the savages and many lower animals, and hence we are not able to smell so acutely.  Many persons lose the sense of smell altogether, from neglecting colds in the head.

26.  How we Taste.—­The tongue and the palate have very delicate nerves by means of which we taste.  We cannot taste with the whole of the tongue.  The very tip of the tongue has only nerves of touch or feeling.

27. The use of the sense of taste is to give us pleasure and to tell us whether different substances are healthful or injurious.  Things which are poisonous and likely to make us sick almost always have an unpleasant taste as well as an unpleasant odor.  Things which have a pleasant taste are usually harmless.

28.  Bad Tastes.—­People sometimes learn to like things which have a very unpleasant taste.  Pepper, mustard, pepper-sauce, and other hot sauces, alcohol, and tobacco are harmful substances of this sort.  When used freely they injure the sense of taste so that it cannot detect and enjoy fine and delicate flavors.  These substances, as we have elsewhere learned, also do the stomach harm and injure the nerves and other parts of the body.

29.  The Sense of Touch.—­If you put your hand upon an object you can tell whether it is hard or soft, smooth or rough, and can learn whether it is round or square, or of some other shape.  You are able to do this by means of the nerves of touch, which are found in the skin in all parts of the body.  If you wished to know how an object feels, would you touch it with the elbow, or the knee, or the cheek?  You will say, No.  You would feel of it with the hand, and would touch it with the ends of the fingers.  You can feel objects better with the ends of the fingers because there are more nerves of touch in the part of the skin covering the ends of the fingers than in most other parts of the body.

30. The sense of touch is more delicate in the tip of the tongue than in any other part.  This is because it is necessary to use the sense of touch in the tongue to assist the sense of taste in finding out whether things are good to eat or not.  The sense of touch is also very useful to us in many other ways.  We hardly know how useful it really is until we are deprived of some of our other senses, as sight or hearing.  In a blind man the sense of touch often becomes surprisingly acute.