On the Movement of Animals, Part One

encrusting them, lest in movement the fibers themselves be damaged or lacerated; which I think to be false. For truly, within the nervous or tendinous membrane, there are contained many bundles which have a hexagonal, square, or triangular prismatic form. Each prismatic bundle, however, is formed of many filaments or tendinous fibers, which fibers in each prism are parallel to one another and are bound together by a most tenacious glue, if they are not continued by terminal tendons or membranes, and sometimes they are directly connected to bones or fleshy fibers.

Furthermore, these same bundles are in some places invested and bound together by countless transverse fibers, as is evident in a muscle that has been boiled and then dried, which nervous fibers seem to compose certain reticular membranes together with capillary vessels that bring and carry away blood. And that those fibers are nervous is conjectured from their tenacious and hard consistency, which resists distraction and rupture while we attempt to sever them with the point of a needle.

Moreover, although muscular fibers appear reddish and blood-like, they are nevertheless all white, and that reddish tincture depends upon the influx of blood, by which, as if by sponges, they are filled and perpetually moistened. This is evinced by the fact that if that bloody redness is washed away by water continuously poured over it, those fleshy fibers remain most white, entirely similar to tendinous fibers, to which they are assimilated not only by white color but, furthermore, they possess a strong, tenacious consistency, no differently than tendons and nerves; for they resist powerful traction, as is to be seen in the internal muscle called the Gracilis, which sustains more than 80 pounds without rupture of its fibers; indeed