How to keep well : a text-book of health for use in the lower grades of schools with special reference to the effects of alcholic drinks, tobacco and other narcotics on the bodily life . the approachof a stranger, even in a dark night, and can also distin-guish whether he is white or black. Many animals are more highly endowed with thissense than man. A dog will smell the footsteps of hismaster amid those of a hundred other people, and cantrace him for miles, although he has been for hours outof sight. Pointers also scent game at a great sense of smell is natures sentinel to guard
How to keep well : a text-book of health for use in the lower grades of schools with special reference to the effects of alcholic drinks, tobacco and other narcotics on the bodily life . the approachof a stranger, even in a dark night, and can also distin-guish whether he is white or black. Many animals are more highly endowed with thissense than man. A dog will smell the footsteps of hismaster amid those of a hundred other people, and cantrace him for miles, although he has been for hours outof sight. Pointers also scent game at a great sense of smell is natures sentinel to guardagainst taking improper food into the stomach, andimpure air into the lungs. 125. Hearing. — Next to sight, hearing is the mostimportant of the senses. We could get along withoutbeing able to taste ; but without seeing and hearing,life would be almost a blank. Our ears have their deli-cate structure securely lodged in the temple bones. THE FIVE GATEWAYS OF KNOWLEDGE 157 The outer ear is a piece of gristle covered with skin,and curiously moulded for catching sounds. In animalsit is quite movable: hence the timid rabbit and theintelligent horse prick up their ears to listen. The. nches or TORY NERVE Sectional View of the Nose. tube in the ear is about an inch long, and guides thesound inward just as an air-trumpet does. At the lower end of this passage we find a delicatemembrane stretched across, which serves as a partitionbetween the outer and the middle ear. It is thin andelastic, hence easily broken by a blow or by pushinganything into the ear. If once broken or destroyed,deafness results. The middle ear is really the drum, and in formit resembles an ordinary drum. Three of the tiniestbones in the body stretch across it. They are so smallthat you can easily balance them on the tip of your I58 . HOW TO KEEP WELL finger. One curious thing is, that they are as large ininfancy as they ever will be. The air reaches the inside of our ear-drum througha little tube about an inch lon
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