So far only can the physiologist take us. Physiology may teach us how to develop our powers and economize our strength; it is already beginning to convert medicine from an art into a science; it will, it is to be hoped, shortly work a revolution in our at present barbarous ideas of how to rear and educate children; it may, in short, teach us how to make the very most of life and die easily; but not until, if ever, it understands the physical basis of life, and perhaps not even then, will it be likely to succeed in prolonging a man’s days much beyond the traditional fourscore years. CONCLUSION. While the physiologist is quietly working, making slow but sure progress, his critics, friendly and otherwise, buzz about him like bees. There are some who are in a chronic state of excitement, expecting a revolutionizing discovery from hour to hour; there are others who assure him that he has reached the limit of human powers of comprehension, and can never know much more than he does to-day; and, lastly, there are those who declare that he has done next to nothing, and that his utmost endeavours have failed to effect any real result, and leave all the important secrets of life untouched. No one knows better than the physiologist how mistaken is the oversanguine class first mentioned. In no department of science, certainly not in physiology, is it possible to reach the top of the ladder by a bound; each rung must be mastered in order. In invading the unknown land the scientist must thoroughly explore and effectively occupy as he advances. He must annex as he goes along; the flying columns which try to reach the enemy’s capital by a dash are never heard of again. In physiology the publication of the various steps is sometimes withheld until the objective has been reached, but our knowledge of life is like Solomon’s temple: a David collects the material, and his successor raises the edifice. The world watches it grow. It is not like those bewildering and unstable palaces of the ‘Arabian Nights,’ built by genii in a single night, and often vanishing as mysteriously. In every age there have existed people who declare that men can never know more than they do at the moment. There were plenty of them when the science of physiology was unborn, and there will be plenty more of them a hundred years hence; only then they will refer with tolerant amusement to the crude and elementary ideas of their predecessors at the beginning of the twentieth century.