steady streams to the heart, with an intensity of force equal to that with which the ventricles repel them through the arteries. Every repulsion of a fluid, in elastic bodies, produces expansions, and every attraction is succeeded by contractions of these bodies, according to a law of these forces, viz: repulsions expand, and attractions contract with powers proportioned to their quantities in given spaces. Every repulsion of the heart, repels or pushes the fluids in the arteries, and every attraction pulls the fluids in the absorbent vessels. The water The motions of the pulse correspond exactly with these laws and these motions; for every repulsion is succeeded by an expansion in the artery, and every attraction by a contraction of it. The same phenomena is found in the hose of the fire engine when in motion. moves in the hose from the cistern or hydrant in a steady stream to the engine, and from the engine through the hose with the motions of the pulse. When the heart is laid open and distended in a circular manner, as seen in the following figure, it is found by the manner in which it is constructed to have four large poles in its circumference; a a, and c c, the axis of which cross each other in the centre of the heart, like those of the circumference of the brain, The forces from the poles; a a, radiate along the ligaments or braces, called calumnæ cornea, to the sides of the ventricles; bb, and the forces also radiate from the poles in the oracles c c, along their ligaments, as seen in the figure: all of which are first expanded and then contracted in the motions of the heart, by the action of the forces from the poles. dd, walls of the heart; e e, septum or division between the auricles and ventricles, and equator between the poles; ff, pericardium or heart case. CHAPTER II. Secreting system-Its organs and vessels-The secretions and chyle are all attracted to the heart, and the excretions repelled from it to the internal and external surfaces of the body-Secreting and excreting systems of the vegatable kingdom. In our first chapter we attempted to give a concise view of the motive system which was formed for the purposes of motion. The excretions, it will have been seen, are attracted from the blood and then repelled from the body. On a farther examination of the human structure, we find another system in which chyle is attracted from the mass in the intestines; lymph, from the lymphatic glands, and fluids from the stomach as well as from every other cavity of whatever size or kind in the whole structure, and conveyed to the heart. We find, therefore, one formative system in which the fluids are attracted to the centre of the body, and a motive system by which they are repelled from it. The existence of such a system as this is indispensable, not only to furnish the fluids necessary for the support and growth of the body, but to supply the waste of those that are necessarily repelled from it, to maintain its different surfaces in positive and negative states, for the purposes of motion. This system consists of a vast number of minute vessels taking their origin with patulous or expanded orifices in almost every part of the skin, serous and mucous membranes, and in nearly all the most minute, as well as the largest cavities of the body. They unite and increase in size as they advance from these surfaces and cavities, in proportion to distance, in two divisions, one from the upper, and the other from the lower part of the body, and at length uniting with two large veins very near the heart called vena cava. In their course to these veins they pass into and then out of a great number of glands, varying in size from that of a small seed to a large bean, which attract from the blood and mix with the fluids in these vessels a semi fluid called lymph, and are hence callea lymphatic glands. When these are viewed through a magnifying glass, we can see the vessels and the nerves b b and c c, penetrating the gland on one side and passing out of it on the other, as seen in fig. 13. The lymph secreted by these glands is very thin, under the influence of the natural temperature of the body in health, but when it is reduced the lymph becomes more or less thick, according to the amount of the reduction, and its motion in these minute vessels becomes more or less difficult. Some of these vessels become entirely obstructed in this way, and the lymph secreted by many of these glands, is accumulated in them, in consequence of these obstructions by which the glands themselves are expanded. By these accumulations the glands are sometimes enlarged in various parts of the body, to the size of that seen in the figure, before they cease secreting, when the accumulated lymph begins to harden down, and sometimes in a few weeks or a few months becomes as hard as old cheese, and looks, as well as cuts like it. On opening the gland with a scalpel in this state, its interior presents a beautiful conglobate arrangement of the acini, as seen in fig. 14, and as the same is seen through a magnifying glass, fig. 15. The organization, it will be seen, is geometrical, and constitutes a beautiful comparison with the conglobate form of snow, as seen through a microscope, Fig. 16, constructed geometrically in the atmosphere with the same forces that produce motion in the gland. There are two classes of these glands in regard to size and situation which are connected with the brain, through the spinal cord, by the nerves of sensation, while the mucous glands of the mucous and mucoserous membranes are connected with it, through the same channel, by the motor nerves or nerves of motion. The lymphatic glands of the largest class are situated in places near the structures to which they belong, and are called by different names, according mostly with the names given to the places in which they are found, while their sattellites, with which they are connected, or those of the smallest and most numerous class are situated in the substance of the structures. The thymus gland of the first class is situated under the sternum or breast bone,-assists in the office of secretion for the infant, and disappears at an age when every other part of the animal system becomes perfectly developed. The pineal gland is situated in the brain, glandula concatenatæ or series of glands in the neck, the thyroid gland upon the cricoid cartilage in the lower and front part of the neck, the bronchial around the bronchial tubes, the cardiac near the heart, the axillary in the armpits, the dorsal along the dorsal, and lumbar along the lumbar vertebræ, the mesenteric in the mesentery or caul attached to the stom-. ach and intestines, the pelvic in the pelvis, the sacral in the sacrum, the inguinal in the groin, and popliteal in the ham, &c. The series of these glands along the neck with some of their sattellites, together with the principal nerves of the neck and face with which they are connected, may be seen in Fig. 17. |