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. [Illustration: Vein, artery and capillary] 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.