On the Movement of Animals, Part One

with AG, CH, then the fibrous prisms are necessarily thickened, otherwise they would not fill the space. Therefore the contracted fibers of the muscles become thicker, which is against their hypothesis.

Secondly, all fibers in a straight muscle parallel among themselves are shortened. Therefore, lest there be penetration of bodies, they must be inflated and thickened. And thus the thickness of the whole muscle must be increased, which they likewise denied.

Thirdly, in an intercostal oblique muscle, the ribs are brought close to each other, and all fibers are shortened at the same time, nor can their interstices be widened, since rather the obliquity of the fibers is increased. Therefore, the entire mass of the muscle will be diminished, which they also denied.

Finally, what is most important in this matter is the mechanical ratio by which, by means of an organ, the force of the muscle moves a resistance. Furthermore, the constitution and arrangement of the muscle, or rhomboidal organ, seems most inept for lifting the weight R. This could easily be shown clearly by demonstration through those things which are to be set forth hereafter; but so that the doctrinal order is not disturbed, it will suffice to settle the matter with sensory experiments.

b Tab. 1. Fig. 6.

Let there be taken two wooden rulers AC, BD, equal, and they shall be connected by several equal threads AB, CD, &c., and the end of the rod A shall be fastened with a nail fixed at E, and to the end D shall be applied the weight R. You will see first that the rhomboidal figure ABDC being destroyed, the rod BD is united, and drawn to the contact of the ruler AC, so that from them is made a single straight line AC, DR perpendicular to the horizon.

c Tab. 1. Fig. 7.

And if the frequency and thickness of the intercepted ropes prevent the contact of the rods, there will arise a constricted and elongated rhomboid, whose diameter ADF