[g] I shall not here intrench so much upon the Anatomist’s Province, to give a Description of the Lungs, although it be a curious Piece of God’s Workmanship; but refer to Seignior Malpighi, the first Discoverer of their Vesiculæ in 1660, in his two Letters to Borelli de Pulmon. Also to Dr. Willis’s Pharm. Rat. p. 2. S. 1. c. 1. de Respir. Orig. & Us. who as he wrote after Malpighi, so hath more accurately described those parts; and to Mr. Cowper’s Anat. Tab. 24, 25. And if the Reader hath a Mind to see what Opposition Seignior Malpighi’s Discoveries met with at Home and Abroad, and what Controversies he had on that Account, as also his Censures of Dr. Willis’s Descriptions and Figures, he may consult Malpighi’s Life written by himself, pag. 4 to 21.
That the Lungs consist of Vesiculæ, or Lobuli of Vesiculæ admitting of Air from the Bronchi, is visible, because they may be blown up, cleansed of Blood, and so dried. But Mr. Cowper saith, he could never part the Lobuli, (so as to make Dr. Willis’s Fig. 1. Tab. 3. & 4.) so that probably the Vesiculæ are contiguous to one another throughout each Lobe of the Lungs. And not only Air; but Diemerbroeck proves, that the Vesiculæ admit of Dust also, from two asthmatick Persons he opened; one a Stonecutter’s Man, the Vesiculæ of whose Lungs were so stuffed with Dust, that in cutting, his Knife went as if through an Heap of Sand; the other was a Feather-driver, who had these Bladders filled with the fine Dust or Down of Feathers.
[h] There is a considerable Difference between Dr. Willis, and Etmuller, viz. Whether the Vesiculæ of the Lungs have any muscular Fibres or not? Etmuller expressly saith, Nullas Fibras musculosas, multo minùs rubicundam Musculorum compagem (sunt enim Vesiculæ albidæ & fere diaphanæ) in ipsis reperiri. ubi supr. c. 6. §. 2. And afterwards, §. 3. Pulmones esse molles flexilesque musculosis fibris ceu propriæ explicationis organis destitutos. But Dr. Willis as expressly alerts they have musculous Fibres, and assigns an excellent Use of them; Cellulæ istæ vesiculares, ut nixus pro expiratione contractivos edant, etiam fibras, utì per Microscopium planè conspicere est, musculares obtinent, ubi supr. §. 16. And in the next §, Ut pro datâ occasione majorem aëris copiam exsufflent, aut materiam extussiendam ejiciant, fibris muscularibus donatæ, sese arctiùs contrahunt, contentaque sua penitùs exterminant. Et enim ordinariæ pectoris Systolæ, quas musculorum relaxationes ex parte efficiunt, aërem forsan totum à Tracheâ & Bronchiis, haud tamen à Vesiculis, quâque vice ejiciunt: propter has (quoties opus erit) inaniendas, & totius Pectoris cavitas plurimùm angustatur, & cellulæ ipsæ vesiculures à propriis fibris constrictis coarctantur.
[] Circa hos motus [Scil. Pectoris dilatationem, &c.] divini Conditoris mechanicen, ad regulas Mathematicas planè adaptaram, satis admirari non possumus; siquidem nullâ aliâ in re manifestùs Ὁ Θεὸς γεωμετρεῖν videtur. Quippe cùm pectoris, tum ampliato, tum coarctatio à quibusdam Musculis (quorum munus unicum est contrahere) perfici debeat; res ita instituitur, ut Costæ quæ thoracis, volut parallelogrammi oblongi versus cylindrum incurvati, latera efformant, in figuram modò quadratam, cum angulis rectis, pro pectoris ampliatione; modò in rhomboeidem, cum angulis acutis pro ejusdem contractione, ducantur, &c. Willis, ubi supr. §. 28.
Galen having spoken of the Parts ministring to Respiration, concludeth, Nihil usquam à Naturâ ullo pacto per incuriam, fuisse præteritum, qua cùm omnia præsentiret & provideret, quæ sunt necessaria illa, quæ causa alicujus extiterunt, confecutura, omnibus instaurationes parare occupavit, cujus apparatus copiosa facultas admirabilem Sapientiam testantur. De us. part. l. 5. c. 15. See also l. 6. c. 1.
[k] For the Structure of the Intercostals, Midriff, &c. I shall refer to Dr. Willis, and other Anatomists. Bur Dr. Drake taxeth Dr. Willis with an Error in fancying there is an Opposition in the Office of the Intercostals, by reason that the Fibres of the external and internal Intercostals decussate; that therefore the external serve to raise the Ribs, the internal to draw them down. But Dr. Drake is of Steno’s, and Dr. Mayow’s Opinion, that notwithstanding the Decussation of their Fibres, the Power they exert upon, and the Motion they effect in the Ribs, is one and the same. Drake’s Anat. l. 2. c. 7. and l. 4. c. 5. Mayow de Respir. c. 7.
[l] Although Dr. Drake and some others deny the Intercostals being Antagonist-Muscles, as in [the preceding Note], yet they, and most other Anatomists that I have met with, attribute a considerable Power to them in the act of Respiration, as they do also to the Subclavian and Triangular Muscles: but the learned Etmuller denies it for these three Reasons, 1. Quia respirando nullam in illis contractionem sentio. 2. Quia——sibi invicem non adducuntur, &c. 3. Quia Costæ omnes ab aliis modò enarratis musculis moventur, idque simul, &c. Intercostales itaque, necnon Subclavios Musculos Costis, parietum instar, ad complenda interstitia intercostalia, pectusque integrandum, ac Costas connectendas, intertectos esse, probabiliter concludo; quo munere triangulares etiam——fungi, rationi consentaneum est. Etmul. Dissert. 2. cap. 4. §. 6.
But as to the Use of the Triangular Muscle in Respiration, we may judge of it, from its remarkable Size, and Use in a Dog; of which Dr. Willis gives this Account from Fallopius: In Homine parvus adeò & subtilis iste [Musculus] est, ut vix pro Musculo accipi queat: in Cane per totum os pectoris protenditur, & cartilagines omnes, etiam verarum Costarum sterno inosculatas, occupat: Cujus discriminis ratio divinam circa Animalium fabricas Providentiam planè indigitat. Quippe cùm hoc animal, ad cursus velocissimos & diu continuandos natum, quo sanguis, dum intensiùs agitatur, ritè accendatur eventileturque, aërem celerrimè & fortiter uti inspirare, ita etiam exspirare debet——idcirco propter hunc actum firmiùs obeundum (cujus in Homine haud magnus est usus) musculus caninas molem ingentem & tanto operi parem fortitur. Willis ubi supr. §. 32.
[m] Ray’s Wisdom of God in the Creation, p. 343.
[n] Mr. Cheselden, an ingenious and most accurate Anatomist, having somewhat particular in his Observations about the Circulation of the Blood through the Heart of the Fœtus, I shall present the Reader with some of his Observations, which he favoured me with the Sight of. The Blood (saith he) which is brought to the Heart by the ascending Cava, passes out of the right Auricle into the left, through a Passage called Foramen Ovale, in the Septum [common to them both] without passing through the right Ventricle (as after the Birth) while the Blood from the descending Cava passeth through the right Auricle and Ventricle into the pulmonary Artery, and thence into the Aorta through the Duct, betwixt that and the pulmonary Artery, called Ductus Arteriosus, whilst a small Portion of the Blood, thrown into the pulmonary Artery passeth through the Lungs, no more than is sufficient to keep open the pulmonary Vessels. Thus both Ventricles are employed in driving the Blood through the Aorta to all Parts of the Fœtus, and to the Mother too. But after the Birth, the Blood being to be driven from the Aorta through the Fœtus alone, and not the Mother too, one Ventricle becomes sufficient, whilst the other is employed in driving the Blood through the Lungs, the Ductus Arteriosus being shut up by means of the Alteration of its Position, which happens to it from the raising the Aorta by the Lungs when they become inflated. After that the Blood is thus driven into the Lungs, in its return it shuts the Valve of the Foramen Ovale against the Foramen it self, to whose Sides it soon adheres, and so stops up the Passage. The Ductus Arteriosus, or Ductus Arteriosus in Ligamentum versus, is seldom to be discerned in adult Bodies, but the Figure of the Foramen Ovale is never obliterated.