250 INDESTRUCTIBILITY OF MATTER. 



under Anabolism, while Katabolism designates the tearing- 

 down, or destructive processes. All the processes of nutri- 

 tion, both of building up and tearing down, are included in 

 the term Metabolism. 



The Indestructibility of Matter. We are agreed that 

 we cannot destroy matter. We may demolish a house, but 

 the material is all there. We may burn it ; but if we could 

 gather the ashes and that part of the smoke and gases 

 furnished by the material of the house, the weight would 

 all be recovered. 



In the continual wasting away of our bodies, there is no 

 real loss of matter. Our weight is reduced ; but the wastes 

 are still part of the earth or air, and are used again. For 

 instance, a particle of carbon in the carbon dioxid of the 

 expired breath may be taken in through a blade of grass in 

 an adjoining field. A cow may eat the grass, and we may 

 soon take the very same particle of carbon in the flesh or 

 milk of the cow. Or the carbon may be taken by that kind 

 of grass called wheat, and become part of the seed or grain of 

 wheat, and be made into flour and be eaten as bread, and be 

 part of us once more. Or this particle of carbon might be 

 carried by the winds to Florida or California, and become part 

 of an orange, and come again to make part of our bodies. 

 Thus there is a ceaseless round of matter into and out of our 

 bodies. The plants furnish food for us, and we help to make 

 food for them by the wastes of our substance. No one has a 

 monopoly of any portion of matter ; it is now ours, now some- 

 one else's. A particle may pass from one animal to another 

 animal, as when we eat flesh or other animal food. But more 

 often the wastes of our bodies go to make part of the air or 

 the soil, and are then taken by some plant before again be- 

 coming part of our tissues. But we are as unable to destroy 

 matter as we are to create it. 



