Part 51

Of the valves of the veins.—Their form.—Their situation.—Veins which they occupy.—Their size.—Remarks upon their relations with the caliber of the veins.—Their variety.—Their number. 404

Action of reagents upon the venous texture.—Action of the air, water, caloric, the acids, &c. 407

II. Parts common to the Organization of the Vascular System with Black Blood.

Blood vessels. Cellular texture.—Of that which unites the veins to the neighbouring parts.—Of that which is peculiar to them. 408

Exhalants and Absorbents.—Experiments upon venous absorption.

Nerves.—There are but very few of them. 409

ARTICLE THIRD.

PROPERTIES OF THE VASCULAR SYSTEM WITH BLACK BLOOD.

I. Properties of Texture.

Extensibility.—It is very evident.—Venous ruptures however take place.—Various examples.—Their causes are but obscurely known. 411

Contractility—Of this property in the longitudinal and the transverse direction. 413

II. Vital Properties.

Properties of Animal Life.—Result of the experiments upon sensibility.—There is no contractility. 414

Properties of organic life. Sensible Contractility.—It appears to be but slight.—General remarks. 415

Of the venous pulse.—Of its cause.—It is a reflux.—Double cause which produces it. 416

Insensible Contractility.—It appears to exist.—The vital activity is greater in the veins than in the arteries.—Consequences. 419

Observations on the motion of the black blood in the veins.—There is no pulse analogous to that of the arteries.—Agent of impulse of the venous blood.—Causes of delay—Accessory causes of motion.—Resemblance between the motion of the veins and that of the arteries. 420

Sympathies of the veins.—They are very obscure. 424

ARTICLE FOURTH.

DEVELOPMENT OF THE VASCULAR SYSTEM WITH BLACK BLOOD.

I. State of this System in the Fœtus.

The veins are less developed in proportion than the arteries.—Why.—Remarks. 425

II. State of this System during Growth and afterwards.

Various phenomena of childhood, adult age, &c. 427

III. State of this System in Old Age.

The veins are much developed in old age.—This development is only a dilatation.—Its varieties according to different circumstances. 428

IV. Accidental Development of the Veins.

It must be considered, 1st, in tumours; 2d, in the distensions of the different parts. 430