Part 66

Characters of the vital properties.—Different remarks upon these characters. 388

ARTICLE FOURTH.

PHENOMENA OF THE ACTION OF THE MUSCULAR SYSTEM OF ANIMAL LIFE.

I. Force of the Muscular Contraction.

Difference according as it is put into action by stimuli or by the cerebral influence.—Experiments.—Influence of muscular organization upon contraction.—The laws of nature the reverse of those of mechanics in the production of motions.—Multiplication of forces.—Uncertainty of calculations upon this point. 390

II. Quickness of the Contractions.

Varieties according as the contractions are, 1st, from stimuli; 2d, from nervous action.—Different degrees of quickness in different individuals.—Influence of habit upon this degree. 395

III. Duration of the Contractions. 397

IV. State of the Muscles in Contraction.

Different phenomena which they then experience.—Essential remark upon the different modes of contraction. 398

V. Motions imparted by the Muscles.

Simple Motions.—1st. In the muscles with a straight direction.—How we determine the uses of these muscles.—2d. In the muscles with a reflected direction.—3d. In those with a circular direction. 400

Compound Motions.—Almost every motion is compound.—How.—Different examples of compound motions.—Antagonist muscles. 403

VI. Phenomena of the Relaxation of the Muscles.

They are opposite to the preceding. 406

ARTICLE FIFTH.

DEVELOPMENT OF THE MUSCULAR SYSTEM OF ANIMAL LIFE.

I. State of this System in the Fœtus.

It contains but little blood.—Slight contractility at this age.—Influence upon these phenomena, of the blood which then penetrates the muscles.—These organs are then slender and weak. 407

II. State of this System during Growth.

Sudden effect of the red blood which penetrates the muscles, and of the other irritations which are connected with it.—Colour of the Muscles.—Period of the brightest colour.—Varieties of the action of reagents on the fleshy texture of young animals. 410

III. State of this System after Growth.

The thickness constantly increases.—The external forms are more evident.—Colour in the adult.—Innumerable variety. 413

IV. State of this System in Old Age.

Increase of density.—Diminution of cohesion.—Phenomena of the vacillation of the muscles.—Atrophous muscles. 416

V. State of the System at Death.

Relaxation or stiffness of the muscles. 419

END OF CONTENTS TO VOL. II.