This kind of feeling is called the sense of touch.
~13.~ There are other nerves of feeling by means of which we are able to hear, see, taste, and smell, of which we shall learn in another lesson.
Besides these we have nerves which tell us whether objects are cold or hot, and heavy or light.

Nerves of feeling also tell us when we are hungry, or thirsty, or tired, and when we need more air to breathe.
~14.

Nerves of Work.~--There are other nerves which are made just like the nerves of feeling, but which do not feel.

These nerves have a very different use.

They come from cells in the brain which have charge of the different kinds of work done in the body, and they send their branches to the parts which do the work; hence we call them _nerves of work_.
~15.~ One set of cells sends nerves to the heart, and these make it go fast or slow as is necessary.