Part 24

MOTHER: No; it went through as quickly as it could, and on its way back found itself in bigger tubes, which keep growing larger; for it is now on its way back to the heart. This picture will help you to see the road it travels. It is now a dark red color, and unfit to work longer till it is washed. Back it goes to the heart, the tubes through which it travels growing larger all the way until it tumbles into the right top room of the heart, which, as you have learned, always has dirty, worn-out blood in it. But it is not allowed to stay there; for between this room and the lower right room there are three folding doors kept in place like the two on the left side, and through them it passes. The walls of the rooms on the right side of the heart are not as thick as those on the left side. I think that must be because the left side sends the blood farther than the right.

HELEN: Does the blood stop to rest in the lower right room?

MOTHER: Oh, no; it never rests as long as there is any life in it! The heart squeezes it out into another big tube, and it soon finds itself in the bath room, where it is washed through and through, and its color becomes as bright red as when new.

AMY: And where does the blood then go?

MOTHER: Straight back to the left side of the heart, where it is pumped out the same as before; and this time we will say it goes to the kitchen of the house you live in, and helps the cook get the dinner you have eaten ready to be made into more blood. The old blood eats some of the good things, and again it is sent to the right side of the heart and back through the bath room.

PERCY: And what then?

MOTHER: Its next trip may be taken to the brain, to help a little girl learn her lessons in school. The brain takes what it can use, and back the blood goes to the right heart, around through the bath room again, and the next time it may be sent to the liver, where it finds sugar and bile-making going on, as usual.

ELMER: But how can the blood be of any use there?

MOTHER: I think you would not ask such a question if you could go there to see. It “takes all the starch out of it,” as you sometimes say, and some other things besides, to make into sugar. It also uses part of it to make into bitter bile, so you may well believe that when it goes back to the heart there is not much left that is of value. But after a good wash in the bath room the blood goes back to the heart, and this time may be sent to the bones in your fingers, and they take what lime it has. This drop was just making its way back to the heart again when Amy cut her finger and let it out.

PERCY: But I should have thought the blood would have been worn out making so many trips.

MOTHER: So it would if it was not made new by the food you eat. It keeps taking as well as giving as it goes round and round through the body. You would not expect a housekeeper to keep everything tidy and clean in a house, and not give her what she needed to make her strong and able to work; and so the master of the house gives the blood plenty to eat; and it makes no complaint as long as it can do its work well. It is a very busy person, we might say, and, as there is no end of things to do in the house in which you live, the blood works night and day.

ELMER: But I don’t see how the blood can take with it all that is needed to mend the different parts of the house.

MOTHER: It is supposed to carry with it a supply of everything that is needed to keep the house in order as it goes, so that when a bone says, “I want some lime,” or a muscle says, “Please give me some al-bu´men,” each part gets what it calls for if it is in the blood. Whether it has what every part needs depends on what the master of the house sends into the kitchen to make blood. Have I told you about the filters in the body?

AMY: I’m sure you have not. Please tell us now.

MOTHER: There are two of them in the lower part of the trunk close to the back, one on each side. They are the shape of a bean, and are called the kidneys. The blood passes through them, and some of the poisons it has picked up are strained out and sent to a storeroom, called the bladder, where they are kept till the brain gives an order to send them away.

HELEN: But there is one thing I would like to know. I can see how blood can run down-hill into our fingers and toes, but I can’t see how it can climb back up to the heart again. Will you please tell me?

MOTHER: The heart is the power that sends it through the arteries to every part of the body, whether it is up-hill or down. Now when the blood has come to the end of its journey, and has reached the tiny hair-like veins of which I told you, more blood keeps coming down and pushes it on till it starts back through the larger veins. The blood keeps crowding behind, and the veins are made in such a way as to help it climb up.

PERCY: But how are they different from the arteries?

MOTHER: Did you ever see little watch-pockets hung in bedrooms in which to put watches? Well, the veins have tiny pockets in them, as you see in the picture.

AMY: But I don’t see how that helps the blood in climbing.

MOTHER: It is this way: If you had a tube with little pockets and should hold it so the top of the pockets was down, you could pour anything through it and they would not stop it from passing. But turn the tube the other way, with the pockets up, as you see in the picture, and they would catch and hold anything you tried to pour through the tube. It is the same way with the veins and the blood. If the blood should try to go back, the pockets would fill full and hold it, but when it is passing up toward the heart, they let it slip by without holding it back.

ELMER: Then the blood keeps going round and round in the body, and never stops.

MOTHER: Yes; and this “going round and round,” as you say, is called the cir-cu-la´tion. This drop of blood would have kept going until it was used up in mending your body and helping keep it alive, if it had not slipped out through the cut in Amy’s finger into the world in which you live and move.

I know you have all enjoyed hearing how the blood travels through the body. Let me tell you a little story I read of what a boy said in school. His teacher asked him to tell the class how the blood cir´cu-lates, or goes round and round.

“Please, sir,” said the lad, “the blood goes down one leg and up the other.”

“Very clever of it, I am sure,” said the teacher. “How does it get across?”

Perhaps that was something the boy had not thought of, and I am sure you would never give such an answer as that since you have heard the story of a drop of blood. Let us see the cut finger where it came out.

AMY: It doesn’t bleed at all now, mother.