8thly. Lymphatic Vessels; which are small cellular canals, that convey the lymph in different parts of the body.
9thly. Glands; which are kernels formed to secrete or separate various humours from the blood.
10thly. Nerves; these are medullary branches springing from the brain, and distributed in the most minute parts of the body; ordained to give the act of sensation, as the soul of animal activity.
11thly. Hair and nails; these are a horny substance, and appropriated either for defence or warmth of the different parts where they are placed.
The fluids; are, 1st. Blood; which is circulated in the arteries and veins, and is the nutriment and source of life.
2dly. The different humours separated by the glands from the blood; of which there are many, as the lymph, serum, spittle, seed, chyle, urine, gall, &c. appropriated to different uses, as hereafter will be described.
3dly. Fat, and marrow in the bones; which are designed not only as a store of nourishment, but to lubricate and warm the parts where they are lodged.
These are the principal materials which compose our wonderful machine. There are various other parts mentioned by Anatomists, both solids and fluids; but as this is designed only to give a universal idea of the most material parts of the structure of this stupendous fabric, we will let this definition suffice, and now consider with what order the principal organs of life act, either in consort, or in opposition to each other.