De Motu Animalium

and it is conjectured that those fibers are nervous from their tenacious and hard consistency, which resists being pulled apart and rupture when we attempt to divide them with the point of a needle.

Moreover, although fibræ musculosæ muscular fibers appear reddish and bloody, they are all white, and that reddish tincture depends on the influx of cruoris blood, by which they are filled and perpetually moistened like sponges. This is proven by the fact that if that bloody redness is washed away by water poured over them continuously, those carneæ illæ fibræ fleshy fibers remain most white, similar entirely to the fibris tendinosis tendinous fibers, to which they are assimilated not only by their white color but also by their strong and tenacious consistency, no less than tendons and nerves have; for they resist strong traction, as can be seen in the muscle called the musculo interno gracili internal slender muscle, which supports more than 80 pounds without rupture of the fibers. Indeed, although the fibers themselves are soft, they are not pulled apart, but are shortened spontaneously.

Individual fibers after boiling are inflated, and when inspected with a microscope, they are seen to be little cylinders similar to the twigs of trees, which do not appear to be hollow tubes as are reed pipes; but they are seen to be full of a substance, or a certain medulla marrow/pith, which must be spongy like elder wood. First, because any soft rod which is inflated by an infused humore humor/fluid becomes turgid and directed, it will necessarily be porous, since it is filled by aqueous granules as if by wedges, as is evident in a wetted rope.

Furthermore, the same thing is conjectured from the fact that in musculis sanguine saturatis & exsiccatis muscles saturated with blood and dried, as they are observed in ham with the aid of a microscope, in their fibris fibers are certain bloody droplets or filaments, direct and transverse, distinct among themselves like porphyry stone. This, however, seems impossible to happen if the internal substance of the fibers were not spongy.

Otherwise, the vessels and capillary nerves binding the prismatic bundles are finer than the columnæ columns or fibrillæ musculosæ muscular fibrillae, which nevertheless do not exceed the thickness of a human hair.

Finally, transverse bindings do not seem to exist in the prisms or muscular bundles, except loosely, since tendons, nerves, and membranes do not suffer any contraction when muscular fibers are shortened and act. And this is evident in the anatomy of the living, and especially in the membrane of the diaphragmatis diaphragm, which is corrugated while the enclosed muscular fibers are contracted.

PROPOSITION II.

The muscle does not differ from flesh.

The error of the ancients must now be rejected; for they distinguish the muscle from carne flesh, and they think the muscle is an aggregate of tendinous fibers; but that carne flesh is something superadded and different from the fibers, namely that it is a tomentum villosum woolly padding encrusted by blood, clothing those tendinous fibers. They prove this with such an argument: because in animals that are very emaciated or starved to death, the fibrous muscles themselves become very thin and fleshless, and the ani-