You will be astonished when I tell you what this curious play of carbon amounts to. A candle will burn some four, five, six, or seven hours. What, then, must be the daily amount of carbon going up into the air in the way of carbonic acid! ... Then what becomes of it? Wonderful is it to find that the change produced by respiration ... is the very life and support of plants and vegetables that grow upon the surface of the earth.