were imbedded many feet below the surface of the earth, and, on being exposed to the air, exhibited signs of life."

445. The renovation of the bone, muscle, ligament, tendon, cartilage, fat, nerve, hair, &c., is not perfected merely by the general circulation of the fluid which is expelled from the left side of the heart, but through the agency of a system of minute vessels, which, under ordinary circumstances, cannot be seen by the eye, even when aided by the microscope; still, minute as they are, the function of these agents is necessary to the continuance of life. They are the smallest capillary vessels.

446. "As the blood goes the round of the circulation, the nutrient capillary vessels select and secrete those parts which are similar to the nature of the structure, and the other portions pass on; so that every tissue imbibes and converts to its own use the very principles which it requires for its growth; or, in other words, as the vital current approaches each organ, the particles appropriate to it feel its attractive force,- obey it,quit the stream,-mingle with the substance of its tissue, and are changed into its own true and proper nature."

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447. Thus, if a bone is broken, a muscle or a nerve wounded, and, if the system is in a proper state of health, the vital economy immediately sets about healing the rupture. The blood, which flows from the wounded vessels, coagulates in the incision, for the double purpose of stanching the wound, and of forming a matrix for the regeneration of the parts. Very soon, minute vessels shoot out from the living parts into the coagulum of the blood, and immediately commence their operations, and deposit bony matter, where it is required to unite fractured bones, and nervous substance to heal the wounded nerve, &c.

445. Show how the renovation of the bones, muscles, &c., is perfected. 446. What is said of the office of the nutrient capillary vessels? 447. When a bone is fractured, by what process is it healed?

448. But the vital economy seems not to possess the power of reproducing the muscles and true skin, and therefore, when these parts are wounded, the rupture is repaired by a gelatinous substance, which gradually becomes hard, and sometimes assumes something of a fibrous appearance. It so perfectly unites the divided muscle, however, as to restore its functional power. When the cuticle is removed, it is reproduced and no scar remains; but, when the true skin is destroyed, a scar is formed.

449. It is not uncommon that the nutrient arteries have their action so much increased in some parts, as to produce preternatural growth. Sometimes the vessels whose function it is to deposit fat, are increased in action, and wens of no inferior size are formed. Again, there may be a deposition of substances unlike any known to exist in the body. Occasionally, these nutrient arteries of a part take on a new action, and not only deposit their ordinary substance, but others, which they have not heretofore secreted, but which are formed by vessels of other parts of the body. It is in this way that we account for the bony matter deposited in the valves of the heart and brain, also the chalky deposits around the fingerjoints.

450. In infancy and childhood, the function of nutrition is very active; a large amount of food is taken, to supply the place of what is lost by the action of the absorbents, and also to contribute to the growth of the body. In middle age, nutrition and absorption are more equal; but in old age, the absorbents are more active than the nutrient vessels. The size, consequently, diminishes, the parts become weaker, the bones more brittle, the body bends forward, and every function exhibits marks of decay and dissolution.

451. A string instance of active absorption in middle

448. What occurs when a muscle is divided? 449. State some of the results of an increased action of the nutrient arteries. 450. When is nutrition most active? How in middle age? How in old age? 451. Relate a striking instance of active absorption in middle age.

HYGIENE OF NUTRITION.

455. Healthy nutrition requires pure blood. If the nutrient arteries of the bones are supplied with impure blood, they will become soft or brittle, their vitality will be impaired, and disease will be the ultimate result. The five hundred muscles receive another portion of the blood. These organs are attached to, and act upon the bones. Upon the health and contractile energy of the muscles depends the ability to labor. Give these organs of motion impure blood, which is an unhealthy stimulus, and they will become enfeebled, the step will lose its elasticity, the movement of the arm will be inefficient, and every muscle will be incapacitated to perform its usual amount of labor.

456. When the stomach, liver, and other organs subservient to the digestion of food, are supplied with impure blood, the digestive process is impaired, causing faintness and loss of appetite, also a deranged state of the intestines, and, in general, all the symptoms of dyspepsia.

457. The delicate structure of the lungs, in which the blood is or should be purified, needs the requisite amount of pure blood to give them vigor and health. When the blood is not of this character, the lungs themselves lose their tone, and, even if permitted to expand freely, have not power fully to change the impure quality of this circulating fluid.

458. The health and beauty of the skin require that the blood should be well purified; but, if the arteries of the skin receive vitiated blood, pimples and blotches appear, and the individual suffers from "humors." Drinks, made of various

455-462. Give the hygiene of nutrition. 455. What is the effect of impure blood upon the bones? On the muscles? 456. On the digestive organs? 457. On the lungs? 458. What is the effect if the vessels of the skin are supplied with vitiated blood?

age was exhibited in the person of Calvin Edson, of Ver. mont, who was exhibited in the large towns of New England, as the "living skeleton." In early manhood he was athletic, and weighed one hundred and sixty pounds; but the excessive action of the absorbents over the nutrient vessels, reduced his weight, in the interval of eighteen years, to sixty pounds.

452. Instances, on the other hand, have occurred, of the action of the nutrient vessels exceeding, in an extreme degree, those of absorption; as in the person of a colored girl, thirteen years of age, who was exhibited in New York in the summer of 1840. She was of the height of misses at that age, but weighed five hundred pounds. Several cases are on record of persons weighing eight hundred pounds.

453. As already mentioned, the blood is the nutritive fluid of animals. When this fluid is coagulated, a thick, jelly-like mass floats in the serum, called fibrin. On the under surmass floats in the serum, called coagulum. This coagulated mass is composed of fibrin and red globulated matter. The color of the red globules is owing to the presence of iron, though some physiologists think it depends on an animal substance of a gelatinous character.

Observation. That portion of the serum which remains fluid after coagulation by heat has taken place, is called se-ros'i-ty. It is more abundant in the blood of old, than in that of young animals; and it forms the "red gravy" in roasted meats.

454. The blood is not necessarily red. It may be white, as in most fish. There is no animal in which the blood is equally red in all parts of the body. The ligaments, tendons, and other white tissues in man are supplied but sparingly with red blood. The fluid that supplies hese tissues is whitish.

452. Of excessive nutrition in early life. 453. Describe the parts that enter into the composition of the blood. What part of the blood forms the red gravy in roasted meats? 454. Is the blood necessarily red? Of what color is the blood of the fish? What part of the human system has white blood ?