PART ONE.

ON THE EXTERNAL MOVEMENTS OF ANIMALS

And Their Forces.

Those things which must be assumed in the Treatise

on the movement of Animals are enumerated.

CHAPTER I.

CONCERNING the local movement of animals, in order for us to discourse methodically, all species of motions which belong to animals must be recounted. First, it is known that an animal migrates from one place to another by transferring its entire mass from one site to another; and if such a transit occurs upon the earth, it is called a gait, or if its transport is effected in water, it is called swimming; but if its translation occurs through the airy, liquid region, it is called flight. One must also consider the various motions and transpositions of the parts of the animal, which are either external, such as those of the hands, legs, the head, etc., or internal, of the viscera, heart, arteries, veins, or of muscles, bones, and other parts of this kind. Or, finally, they are the flux and motions of liquids through the cavities and vessels of the animal, such as blood and other humors. Therefore, that we may inquire into the faculties, instruments, and contrivances by which nature executes those primary external motions,