The body is constantly undergoing a process of change and regeneration. Old cells are being cast off every second, and new cells are taking their places. Our muscles, tissues, hair, nails, nerves, brain substance, and even our bones are constantly being made over and rebuilt. Our bodies to-day do not contain a single particle of the material which composed them a few years back. A few weeks suffices to replace our entire skin, and a few months to replace other parts of the body. If a sufficiently large microscope could be placed over our bodies, we would see each part of it as active as a hive of bees, each cell being in action and motion, and the entire domestic work of the human hive being performed according to law and order. Verily, "we are fearfully and wonderfully made." A number of the best authorities have used the illustration of the process of the cells in healing an ordinary wound, in order to show the activity and "mind" of the tiny cells. We have become so accustomed to the natural healing of a wound, scratch or broken skin, that we have grown to regard it as an almost mechanical process. But, science shows us that there is manifested in the healing process a marvellous degree of life and mind in the cells. Let us consider the process of healing an ordinary wound, that we may see the cells at work. Let us imagine that we are gazing at the wounded part through a marvellously strong microscope which enables us to see every cell at work. If such a glass were provided we should witness a scene similar to that now to be described.