CHAP. 88.—THE NERVE: ANIMALS WHICH HAVE NONE.
The nerves312 take their rise at the heart, and even surround it in the ox; they have the same nature and principle as the marrow. In all animals they are fastened to the lubricous surface of the bones, and so serve to fasten those knots in the body which are known as articulations or joints, sometimes lying between them, sometimes surrounding them, and sometimes running from one to another; in one place they are long and round, and in another broad, according as the necessity of each case may demand. When cut, they will not reunite, and if wounded, it is wonderful what excruciating pain they cause; though, if completely cut asunder, they are productive of none whatever. Some animals are destitute of nerves, fish, for instance, the bodies of which are united by arteries, though even these are not to be found in the mollusks. Wherever there are nerves found, it is the inner ones that contract the limb, and the outer ones that extend it.
Among the nerves lie concealed the arteries, which are so many passages for the spirit; and upon these float the veins, as conduits for the blood. The pulsation of the arteries is more especially perceptible on the surface of the limbs, and afford indications of nearly every disease, being either stationary, quickened, or retarded, conformably to certain measures and metrical laws, which depend on the age of the patient, and which have been described with remarkable skill by Herophilus, who has been looked upon as a prophet in the wondrous art of medicine. These indications, however, have been hitherto neglected, in consequence of their remarkable subtilty and minuteness, though, at the same time, it is by the observation of the pulse, as being fast or slow, that the health of the body, as regulating life, is ascertained.