_Similar Parts_] Containing parts, by reason of their more solid substance, are either homogeneal or heterogeneal, similar or dissimilar; so Aristotle divides them, lib. 1, cap. 1, de Hist. Animal.; Laurentius, cap. 20, lib. 1. Similar, or homogeneal, are such as, if they be divided, are still severed into parts of the same nature, as water into water. Of these some be spermatical, some fleshy or carnal. [957]Spermatical are such as are immediately begotten of the seed, which are bones, gristles, ligaments, membranes, nerves, arteries, veins, skins, fibres or strings, fat. _Bones_.] The bones are dry and hard, begotten of the thickest of the seed, to strengthen and sustain other parts: some say there be 304, some 307, or 313 in man's body. They have no nerves in them, and are therefore without sense. A gristle is a substance softer than bone, and harder than the rest, flexible, and serves to maintain the parts of motion. Ligaments are they that tie the bones together, and other parts to the bones, with their subserving tendons: membranes' office is to cover the rest. Nerves, or sinews, are membranes without, and full of marrow within; they proceed from the brain, and carry the animal spirits for sense and motion. Of these some be harder, some softer; the softer serve the senses, and there be seven pair of them. The first be the optic nerves, by which we see; the second move the eyes; the third pair serve for the tongue to taste; the fourth pair for the taste in the palate; the fifth belong to the ears; the sixth pair is most ample, and runs almost over all the bowels; the seventh pair moves the tongue. The harder sinews serve for the motion of the inner parts, proceeding from the marrow in the back, of whom there be thirty combinations, seven of the neck, twelve of the breast, &c. _Arteries_.] Arteries are long and hollow, with a double skin to convey the vital spirit; to discern which the better, they say that Vesalius the anatomist was wont to cut up men alive. [958]They arise in the left side of the heart, and are principally two, from which the rest are derived, aorta and venosa: aorta is the root of all the other, which serve the whole body; the other goes to the lungs, to fetch air to refrigerate the heart. _Veins_.] Veins are hollow and round, like pipes, arising from the liver, carrying blood and natural spirits; they feed all the parts. Of these there be two chief, _Vena porta_ and _Vena cava_, from which the rest are corrivated. That _Vena porta_ is a vein coming from the concave of the liver, and receiving those mesaraical veins, by whom he takes the chylus from the stomach and guts, and conveys it to the liver. The other derives blood from the liver to nourish all the other dispersed members. The branches of that _Vena porta_ are the mesaraical and haemorrhoids. The branches of the _cava_ are inward or outward. Inward, seminal or emulgent. Outward, in the head, arms, feet, &c., and have several names. _Fibrae, Fat, Flesh_.] Fibrae are strings, white and solid, dispersed through the whole member, and right, oblique, transverse, all which have their several uses. Fat is a similar part, moist, without blood, composed of the most thick and unctuous matter of the blood. The [959]skin covers the rest, and hath cuticulum, or a little skin tinder it. Flesh is soft and ruddy, composed of the congealing of blood, &c.