“It needs no key to wind it up, No oiling of the wheels, No jeweler to make repairs; With such it never deals. “Near seventy ticks a minute is Its normal race to go; Just place your thumb against your wrist, And you will find it so. “This little clock was made to be A faithful sentinel, To give alarm of any change Within its prison cell. “If you are healthy, then its ticks Are even, full, and strong; By this you know that, in its cell, Nothing is going wrong. “When sickness comes, it works so hard, And is so feeble, too, It can not keep the perfect time Its Maker meant it to. “Now, would you help this little clock The best of time to keep? Then always mind the rules of health, And thus their blessings reap.” —_Mrs. Julia Loomis._ [Illustration: A clock] THE CARETAKER AMY: Just see, mother! I have cut my finger. See how fast the blood runs out! Oh-h! MOTHER: Suppose we let a drop fall on this glass and then try to find out what it is made of, what it does in the body, and about the different rooms it visits. You may ask questions and I will try to answer them; but first we will bind up the cut finger in this bit of soft cloth. We have already learned how blood is made, but we want to learn what it does for us. Blood is made from the food you eat and the water you drink. If you eat good food it makes good blood. Bad food and drink make bad blood. It might be called the caretaker, or the housekeeper of the body. Without it your body-house would go to ruin; for the Bible says, “The life of all flesh is the blood.” After passing through the kitchen, serving room, and dining room, the blood enters a dark tunnel and comes to your heart. HELEN: But what makes it such a bright red color? MOTHER: Because it has millions of little red bodies called cor´pus-cles. Really it is a pale yellow, but there are so many of these tiny folk floating around that they make it look red, just as a river would if it were packed full of tiny red fishes, or as water would if you should fill a bottle with very small red beads and then cover them with water. PERCY: But are all the cor´pus-cles red? MOTHER: No; some are white, but there are many more red than white. AMY: What do they look like? MOTHER: You can not see them at all unless you should look through a mi´cro-scope. The red cor´pus-cles are shaped like a little biscuit with a dimple in the middle. The white ones keep changing their shape in a very wonderful way. First they are round, then square, then three-cornered, and they take on ever so many other shapes. There are several millions of these little red and white fellows in a single drop of blood. [Illustration: _Corpuscles._] ELMER: But you said it went through a dark tunnel to get to the heart. Please tell us about that.