Since that period, surprising changes have taken place in all the nations of Europe; but in none has the change been so great as in England. From that period, when its mortality exceeded that of any great and prosperous European country, its mortality has been steadily diminishing, and at the present time the value of life is greater in England than in any other country in the world. Not only has the value of life been regularly increasing until it has advanced beyond that of any country of which there is any record; but the remarkable fact is established, that the whole mass of its people now live considerably longer than its higher classes did in the seventeenth and eighteenth centuries. Thus, by inspecting the preceding table, it will be seen that between the years 1693 and 1715, the nominees of the tontine of England, at the age of fifty, fell short of the maximum longevity by 269 weeks; whereas, the mass of the people in all England and Wales, between the years 1811 and 1831, fell short of it only by 100 weeks; the entire mass having not only reached the select class, but absolutely advanced beyond it by 169 weeks. There cannot be a more interesting and instructive thing than to connect these facts with their causes. This will be attempted in a subsequent part of this work; but the reader will be incomparably better prepared for the investigation when the processes of life have been explained, and the influence of physical and moral agents upon them traced. And with this exposition we now proceed. CHAPTER V. Ultimate elements of which the body is composed—Proximate principles—Fluids and solids—Primary tissues—Combinations—Results—Organs, systems, apparatus—Form of the body—Division into head, trunk, and extremities—Structure and function of each—Regions—Seats of the more important internal organs. 1. The ultimate elements of which the human body is composed are azote, oxygen, and hydrogen (gaseous fluids); and carbon, phosphorus, calcium, sulphur, sodium, potassium, magnesium, and iron (solid substances). These bodies are called elementary and ultimate, because they are capable of being resolved by no known process into more simple substances. 2. These elementary bodies unite with each other in different proportions, and thus form compound substances. A certain proportion of azote uniting with a certain proportion of oxygen, hydrogen, and carbon, forms a compound substance possessing certain properties. Another proportion of azote uniting with a different proportion of oxygen, hydrogen, and carbon, forms another compound substance possessing properties different from the former. Oxygen, hydrogen, and carbon, uniting in still different proportions without any admixture of azote, form a third compound possessing properties different from either of the preceding. The compounds thus formed by the primary combinations of the elementary substances with each other are called PROXIMATE PRINCIPLES.