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THE TWENTY-THIRD TABLE.
Fig. 1.
REPRESENTS the External Coat of a Vein viewed with a Microscope.
A B C D, The Fibres extended according to the Length of the Vessel, where may be observed the Vasa Vasorum.
Fig. 2.
A, The Second Coat of the Vein, called by Dr. Willis, the Vasculous and Glandulous Coat.
Fig. 3.
The Third or Internal Tunick of a Vein composed of Circular Fibres.
Fig. 4
The External Coat of an Artery consisting of a Rete of small Nerves (A,) Blood-Vessels, (B) and Membranous Expansions (C▪) On this Membrane of the Artery divers Glandulous Bodies appear com∣posing greater and lesser Clusters, D E, variously dispersed.
Fig. 5.
A B, The Second Coat of an Artery consisting of divers Strata of Fibres variously decussating each other, and joyned with the Internal or Third Coat.
Fig. 6.
A B C, The Inner and Smooth Surface of the Third or most In∣ternal Coat of the Artery; where the Foramina for the Branches which arise out of it, are exprest, and its Fibres extended according to its length B, C. The great Trunks of the Arteries do evidently appear to consist of a greater Number of Strata of Fibres, than those of the Veins; but the farther they recede from the Heart, they are both still more and more subdivided, and their Trunks and Capillary Branches become still thinner and thinner, till their outmost Extremities con∣sist of one single transparent Membrane; chiefly composed of such Tubes, as only convey their Succus Nutritius. And this I am apt to think may serve for the Description of Blood-Vessels in general; and shall farther consider the Organization of the several Extremities of the Blood-Vessels, in speaking of their particular Offices relating to Se∣cretion in the several Parts; wherefore at present shall only men∣tion, that the Extremities of Veins and Arteries are continued Chan∣nels, variously contorted and not all of them of an equal Size, even in Parts which are uniform or the same. Vid. App. Fig. 4.5.
After the Blood has past the Extremities of its Vessels, and is in its Return to the Heart again by the Veins; it there meets with divers Valves or Stops, which prevent the Weight of the Blood of the In∣ferior Parts of the Body, and the Recoiling of it in the Superior, (when any violent Motions affect the Thorax, as in Coughing, from pressing on the Extremities of the Vessels, and hindering its progressive Motion. That there is a Recoiling of the Blood in any extraordinary Motions of the Thorax, in the Jugular Veins, may be observ'd in taking Blood from thence, especially in Children. Hence it is the Valves in those Veins are necessary; least the Blood should again repass into the Vessels of the Brain with great Violence; which is also prevented in the Contortion made in the Internal Jugular Vein, in its Specus in the Basis of the Skull. I must confess I never yet observed above Two Valves (one opposite to the other) in the largest Vein that is fur∣nished with Valves; however Anatomists commonly mention Three, and Professor Bidloo tells us of Four and Five Valves, as they ap∣pear in the following Figures.
Fig. 7.
Part of a Vein extended with Wind and dried, having a double Valve or Two Valves of Semilunary Figures, placed opposite to each other.
Fig. 8.
A A, A Portion of the Jugular Vein blowed up and dried; B B B, Its Three-fold Valves.
Fig. 9.
Part of a Vein with Five Valves.
Fig. 10, 11.
A A, The Portions of Veins exprest in the Two preceeding Fi∣gures lay'd open;
B B, &c. Their Valves as they appear in their Insides.
Fig. 12.
The Valves as they appear in the Insides of the Veins according to Bidloo.
Fig. 13.
Two Valves as they appear when taken out of the Veins.
Fig. 14.
The unequal Distance of the Valves in the Veins; the Vestigia of the Valves being here only exprest, as they appear when the Vein is extended with Wind.
Fig. 15.
Represents (according to Bidloo) a System of the Arteries injected with Wax, and free'd from the Body of an Infant Six Months Old; which he tells us he has reserved: If so, it is a great Rarity indeed! For having more than once free'd the Arteries from the Body of an Infant, as well as from an Adult, and finding them far differing from this Figure, and not much disagreeing with the Descriptions and Fi∣gures of Vesalius and others; I cannot look on this, but as a Prodigy in Nature. Wherefore I shall here give you his Description of it, and refer you to my Appendix. Fig. 3. Where their common Ap∣pearance is exprest, as I now have them injected by me, and dissected from the Body of an Infant.
The Arteria Aorta (say's Bidloo) arising from the Heart, soon sends out Two small Coronary Branches. B, in the Body of the Heart. Its Trunk is divided on the Pericordium into the Ascendens C, and Descendens D. The First gives Branches to the Parts above the Heart, and is divided into the Subclavii E, from which the Axillares F, and Internal Mammary G, Three or Four Intercostales H, and Cervicales I. do arise. From the Axillary Artery are Branches com∣municated to the Scapula K, and to the Superior Parts of the Thorax. When it has got between the Muscles of the Cubit, it is divided into Two little Branches; the First of which L, goes to the Wrist, Thumb, and Fore-Finger; the other to the Three other Fingers. It divides into Two about the Thymus, and Forms the Carotides M. These ascen∣ding near the Wind-pipe after having sent several Branches to the Tongue, Larynx and Parts adjacent, and are divided into the Exter∣nal N, and Internal Branch O, the Exterior supplies the Face, Lips, partly the Ear and lower Teeth; the other Branch serves the Forehead, Temples and Neighbouring Parts.
The Inward Branch ascending streight through the Os Sphoenoides creeps under the 'Dura Mater, and forming various Plexus's, in that Part within the Skull, it is cover'd with a particular Coat already de∣scrib'd; it sends out small Branches near the Optick Nerves; but the large Trunks creep back again, sometimes united and by and by se∣parated from each other. There are small Branches convey'd to the Spinal Marrow, partly above and partly below the Heart. From the Axillarie's, and ascending and descending Trunks, it derives several Branches which reflected into a Circle, creep through its Coverings and several Parts of the Head. The descending Trunk of the Aorta D, supply's some of the Intercostals 1, and the Neighbouring Muscles and Parts; there is a large Trunk 2, also sent to the Diaphragm; under the Diaphragm the Branches of the Viscera of the Abdomen are re∣markable. viz. of the Stomach, 3. The Inferior and Superior Me∣seraic Branches, 4, 5, those of the Omentum, or Caul, 6, of the Liver, 7, of the Kidneys 8, the Spermatics 9, and so on. About the Os Sa∣crum this Trunk is divided into Two Branches, from which others are again deriv'd to the Right Gut and Pudenda, some to the Hips, some to the Thighs and Legs, as well Internally, as Externally. Thus much concerning the principal Distribution of the Aorta.
In the next Place Professor Bidloo gives us the Anatomy of the Blood. In the Anatomy of the Blood Chymically performed (say's he) it is manifest there is a Water in it, which as well as it can be, is simply to be considered) a Spirit and Salts both fixt and volatile. Tho' by this Method (he very well say's) some Parts are very accurately disco∣ver'd; yet doth it exceedingly destroy the Appearances of some Figures, which ought by no means to be alter'd; wherefore he proposed the following Figure.
Fig. 16.
A, A small Drop of Blood inclosed in a Glass Tube, and its Parti∣cles by the Help of a Microscope are represented very much magnifyed.
B, The Globular Bladders.
C, The little Fibres variously turned, laid, and disposed, accord∣ing to Bidloo. I must confess I have frequently view'd the Blood in the same Manner as here Exprest with a Microscope, and have con∣stantly observed its Appearance as here represented: Nor could I ever apprehend the Blood was furnished with Fibres (so much talk'd of) but that the Fibrous Appearance it has, (when any Blood-Vessel is open in the Mouth, or in Bleeding into warm Water and the like) is owing to a Coagulation of its Serum, by which Means its Globules are entangled and frame those Fibrous Bodies: The Streaked Mass repre∣sented at D, E. (according to Bidloo) I am apt to think proceeded from a Coagulation of the Serous Part of the Blood, by sealing the Tube Hermetically; in doing which the Glass must be heated. To this our Author adds another Way of Anatomizing the Blood, thus:
The watery whitish Liquor, which is of a different Substance, being separated from the cold coagulated Mass of Blood, and set on the Fire, thickens in a short Time; the red Part which remains, (of which the more fluid Part being frequently washt away with warm Water,) appears like a grumous Heap; every Particle of which resembles a Glo∣bular Bladder; of which, some are Transparent, others not. The rest of the Mass which consists of very flexible Fibres, according to Bidloo, and being exposed to the Air and Cold, become very tough, tensile, and seem like Net-work, owe that Appearance to a Combination of the Globules variously stratified on each other.
The Third Way (which our Author proposes) of enquiring into the Blood, is when the Blood is separated from the Serum or Li∣quor it swims in, and put on a Piece of Paper dawb'd over with Lard, is become a little dry; after an External View of the Particles, gently with the Finger break off a little of the Mass of Blood; in which, you will presently behold little Globes of a differing Frame and Fi∣gure, little Fibres, and Streaks of the same Kind.