On the Movement of Animals, Part One

we shall set forth; but not in those simple muscles which constitute a single rhomb, of which the aforementioned authors speak in express words and exemplify with figures.

PROPOS. VI.

The true figure of muscles is indicated.

That there exist in animals columnar muscles composed of fibers parallel among themselves, such as ABDC, which pull a resistance R through the same direction of the fibers AB, is evident by direct observation, especially in the tongue of the Woodpecker, and in the tails of lobsters, and in many others.

a Tab. 1. Fig. 10.

Furthermore, there are also simple rhomboidal muscles AB, DC, whose oblique fibers AD and CD, annexed to the bone TV, pull towards themselves another bone, or tendon RS, as are the muscles of the abdomen and the intercostals, and others, in which the bone RS, resisting the traction, is moved by a transverse motion parallel to itself, approaching towards the firm bone TV; where it is to be noted that the angle VCD is not rendered less obtuse, but on the contrary, the obtuse inclination is increased.

b Tab. 1. Fig. 11.

In the last place, b there are given penniform muscles, first observed and delineated by Casserio of Piacenza. These indeed are most artfully formed for purposes to be set forth below; but the oblique fibers act by contracting themselves, and from such oblique traction the weight R attached is suspended in the same way as a weight is suspended by two or more ropes pulled obliquely, the force and manner of operating of which we shall declare in its proper place.