PHYSICAL LIFE. PHYSICAL LIFE DEFINED. T is very far from our purpose in this part of our book to undertake a systematic treatise in human physiology, first, because the physiological facts relating to the human species cannot be fully understood without considerable acquaintance with general physiology, anatomy, and organic chemistry; and to introduce these would occupy too much space, and would fail to interest the general reader. Secondly, the plan of this work is to present only the most salient and striking points of the various subjects discussed, and to deduce from them such truths and lessons as will tend to better human life and make happier individual souls. The opinion is an old one, but very good, that the physical life of man is the result of a mysterious union of a vital principle with a material organism, and that death is the result of a separation of the two. Plato and Aristotle held to the idea of three animating spirits, the vegetation of the plant, the vegetative and sensitive in the animal, and in man an additional intelligent and reasoning spirit. Modern psychology supposes the three-fold division of man into body, soul, and spirit, "the spirit being his highest nature, in which he bears the nearest affinity to God, by which he is a moral, conscientious, or religious being; while the soul embraces his animal and secular understanding, by which he is acute in things of sense."-DR. WHEDON. It is in physical life that man is most nearly allied to the creature world around him. He is exposed to the elements, and must have shelter. He has a perishing nature, and must have food. He has frail powers, and must have rest. In the Bible we find descriptions that apply with equal force to animals and man. Thus David says: The high hills are a refuge for the wild goats; and the rocks for the conies. Thou makest darkness, and it is night: wherein all the beasts of the forest do creep forth. The young lions roar after their prey, and seek their meat from God. The sun ariseth, they gather themselves together, and lay them down in their dens. Man goeth forth unto his work and to his labor until the evening. (Ps. civ. 18-20.) So in regard to physical death: For that which befalleth the sons of men befalleth beasts; even one thing befalleth them: as the one dieth, so dieth the other; yea, they have all one breath: so that a man hath no pre-eminence above a beast: for all is vanity. All go unto one place; all are of the dust, and all turn to dust. (Eccl. iii. 19, 20.) But in the very next verse the inspired writer takes in the thought of man's superior part, for he exclaims-who knoweth the spirit of man that goeth upward, and the spirit of the beast that goeth downward to the earth? In physical life, man resembles the animal; in spiritual life there should be none of the animal in him. GROWTH AND MATURITY. According to Mons. Quetelet, the most rapid growth in the human body takes place immediately after birth; the infant in the space of a year grows about two decimeters. The increase in size diminishes gradually, as its age increases, up toward the age of four or five years. When about three, it attains half the size it is to become when full grown. When from four to five years of age, the increase in size is very regular each year up to sixteen years, that is to say, up to the age of puberty; this annual increase is nearly fifty-six millimeters. After the age of puberty the size continues to increase but feebly; when from sixteen to seventeen years old, the individual increases four centimeters (.60 inch). In the two years following, it increases only one inch. The total increase in the size of a man does not appear to be entirely terminated when he is twenty-five years old. Some one proposes the following natural divisions and natural durations for the whole life of man: The first ten years of life are infancy; the second, boyhood; the third, first youth; the fourth, second youth; from forty to fifty-five, first manhood; from fifty age five to seventy, second manhood, and this period of manhood is the of strength and manly period of human life; from seventy to eighty-five, first old age; from eighty-five to one hundred, second old age. These deductions are made from a careful study of the question with all the aids derivable from thorough knowledge of the sciences of anatomy and physiology. The divisions will, of course, vary in different individuals, and overlap each other in the same one. They are given simply as general truth. The limits are not so arbitrary as they may seem at first sight. At ten years of age the second teething is complete and infancy ought to end; at twenty, the bones no longer increase in length, and boyhood naturally ends; at thirty, the body ceases to increase in size, and youth ends, and so on. After forty, whatever increase there may be of the body is in fat; and, instead of increase in strength and activity, this latter growth weakens the body and retards its motion. When the growth ceases absolutely, the body rests, rallies and becomes invigorated. This period of internal invigoration is the first manhood, and lasts fifteen years longer, when the period of old age begins. The following facts in reference to the human body are not new, but are convenient for reference: The average weight of an adult is one hundred and forty pounds six ounces. The average weight of a skeleton is about fourteen pounds. The skeleton measures one inch less than the height of the living man. The average height of an Englishman is five feet nine inches; of a Frenchman, five feet four inches; and of a Belgian, five feet six and three-quarter inches. The average weight of an Englishman is one hundred and fifty pounds; of a Frenchman, one hundred and thirty-six pounds; a Belgian, one hundred and forty pounds. The average number of our teeth is thirty-two. A man breathes about twenty times a minute, or twelve hundred times an hour. A man breathes about eighteen pints of air in a minute, or upward of seven hogsheads in a day. A man gives off 4.08 per cent. carbonic gas of the air he respires; respires ten thousand six hundred and sixty-six cubic feet of carbonic acid gas in twenty-four hours, equal to one hundred and twenty-five cubic inches of common air. A man annually contributes to vegetation one hundred and twenty-four pounds of carbon. The average of the pulse in infancy is one hundred and twenty per minute; in manhood, eighty; at sixty years old, sixty. The pulse of females is more frequent than that of males. The weight of the circulating blood is about twenty pounds. The heart beats seventy-five times in a minute; sends nearly ten pounds of blood through the veins and arteries each beat, and makes four beats while we breathe once. Five hundred and forty pounds, or one hogshead one and onequarter pints of blood pass through the heart in one hour. Twelve thousand pounds, or twenty-four hogsheads four gallons, or ten thousand seven hundred and eighty-two and one-half pints pass through the heart in twenty-four hours. One thousand ounces of blood pass through the kidneys in one hour. One hundred and seventy-four million holes, or cells, are in the lungs, which would cover a surface thirty times greater than the human body. THE BODY A MACHINE. Dr. George Wilson, who compares the human body to a stove, and the food we eat to fuel which, in the ultimate form of carbon, mingled with hydrogen and sulphur, burns in the capillaries, producing heat, goes on to say: "In some of our artificial stoves, little doors or slides are employed to control the admission of air; in furnaces connected with steam-engines, we may have dampers which will accomplish the same purpose by the ingenious workings of the machine itself. "But neither doors nor dampers, pokers nor stokers, can be employed in the bodily apparatus. If, on the one hand, our human fire should begin to flag from undue expenditure of heat, the appetite speaks out sharply, and compels the owner to look round for |