All the nerves do not end in the muscles, but many in the skin. These nerves can not be used to carry nervous impulses from the brain to the skin. By no effort of yours can you make the skin contract. For what purpose then are these nerves? If you prick your finger, you feel the touch, or say that you have sensation in your finger. If you were to cut the nerve leading to the finger you would lose this power of feeling. These nerves, then, ending in the fingers have a different use from those ending in the muscles. The latter carry an impulse from the brain to the muscles, and are called motor nerves. The former carry impulses from the skin to the brain, and are called sensory nerves, or those which bring about sensations. Motor nerves are of but one kind, but there are several kinds of sensory nerves, each kind having a special work to do. The several works which these nerves do are called the senses. By means of these sensory nerves we receive impressions from the external world, sensations of heat, cold, roughness, good and bad odors, taste, sound, and the color and form of things. Thus impressions of the external world are made upon the brain, and it is these impressions that stimulate the brain to action. The brain worked on by them, through ways that we know not of, governs the muscles, sends commands by the motor nerves, and rules the body as a conscious, intelligent will.
[TO THE NIGHTINGALE.]
By DRUMMOND OF HAWTHORNDEN.
Sweet bird, that sing’st away the early hours,
Of winters past or coming void of care,
Well pleased with delights which present are,
Fair seasons, budding sprays, sweet-smelling flowers;
To rocks, to springs, to rills, from leafy bowers
Thou thy Creator’s goodness dost declare,