Note Book 4. Chap. 7. Note 1 — BOOK IV.

[a] The Uses assign’d to Respiration by all the Anatomists before Malpighi’s Discoveries of the Structure of the Lungs, are so various, and many of them so improbable, that it would be frivolous to recount them. But the more eminent modern Anatomists assign these Uses. Willis thus sums up his Opinion, Præcipua Pulmonum functio, & usus sunt, sanguinem & aerem per totas partium compages, intimosque recessus, atq; ductus quosque minutissimos traducere, & ubique invicem committere; in cum nempe finem, ut sanguis venosus à circuitu redux, & chymo recenti dilutus,——tum perfectiùs misceatur & velut subigatur, tum potissimùm ut secundùm omnes suas partes ab aëre nitroso de novo accendatur. Pharmaceut. p. 2. S. 1. c. 2. §. 2. Mayow saith rightly, that one grand Use of Expiration is, Ut cum aëre expulso, etiam vapores è sanguine exhalantes, simul exsufflentur. And as for Inspiration, that it coveyeth a nitro-aerial ferment to the Blood, to which the Animal-Spirits are owing, and all Muscular-Motion. Mayow de Respir. p. 22. &c. meâ Edit.

Somewhat of the Opinion of these two last cited, if I mistake not (it being long since I read their Tracts, and have them not now at hand,) were Ent, Sylvius, Swammerdam, Diemerbroek, and my Friend Mr. Ray in an unpublished Tract of his, and in his Letters now in my Hands.

But our Dr. Thurston, for good Reasons, rejects these from being principal Uses of Respiration, and thinks, with great Reason, the principal Uses to be to move, or pass the Blood from the right to the left Ventricle of the Heart. Upon which account Persons hanged, drowned, or strangled by Catarrhs, so suddenly die, namely, because the Circulation of their Blood is stopped. For the same Reason also it is, that Animals die so soon in the Air-Pump. Among other Proofs he instanceth in an Experiment of Dr. Croon, Profess. Gresh. which he made before our R. S. by strangling a Pullet, so that not the least Sign of Life appear’d; but by blowing Wind into the Lungs through the Trachea, and so setting the Lungs a playing, he brought the Bird to Life again. Another Experiment was once tried by Dr. Walter Needham, before Mr. Boyl, and others at Oxford, by hanging a Dog, so that the Heart ceased moving. But hastily opening the Dog, and blowing Wind into the Ductus Pecquetianus, he put the Blood in Motion, and by that means the Heart, and so recovered the Dog to Life again. V. Thurston de Respir. Us. p. 60, and 63. meâ Edit.

Such an Experiment as Dr. Croon’s my Friend, the late justly renowned Dr. Hook shewed also our R. S. He cut away the Ribs, Diaphragm, and Pericardium, of a Dog; also the top of the Wind-Pipe, that he might tie it on to the Nose of a Pair of Bellows; and by blowing into the Lungs, he restored the Dog to Life; and then ceasing blowing, the Dog would soon fall into dying Fits; but by blowing again, he recovered; and so alternately would die, and recover, for a considerable Time, as long, and often as they pleased. Philos. Trans. Nᵒ. 28.

For the farther Confirmation of Dr. Thurston’s Opinion, the ingenious Dr. Musgrave cut off, and close stopped up the Wind-Pipe of a Dog with a Cork, and then threw open the Thorax; where he found the Blood stagnating in the Lungs, the Arteria Pulmonaris the right Ventricle and Auricle of the Heart, and the two great Trunks of the Cava, distended with Blood to an immense Degree; but at the same Time, the Vena Pulmonaris, the left Ventricle and Auricle of the Heart in a manner empty, hardly a spoonful of Blood therein. Philos. Trans. Nᵒ. 240. Or both the Experiments may be together met with in Lowth. Abridg. Vol. 3. p. 66, 67.

This Opinion of our learned Thurston, the late learned Etmullerus espoused, who being particular in reckoning up the Uses of Respiration, I shall therefore the more largely cite him. Respiration, saith he, serves, 1. Ad Olfactum. 2. Ad Screatum & Sputationem. 3. Ad Oscitationem, Tussim, Sternutationem, Emunctionemque. 4. Ad liquidorum Sorbitionem, Suctionemve. 5. Ad Loquelam, Cantum, Clamorem, Risum, Fletum, Flatum, &c. 6. Ad facum Alvi, Urinæ, Fœtûs Molæve, necnon Secundinarum expulsionem. 7. Ad promovendi Ventriculi, Intestinorum, Lacteorumque vasorum, &c. contenta. 8. Ad halitus aqueos Sanguinis è pulmonibus, aëris ope, exportandos. 9. Ad Diapnoën. 10. Ad exactiorem Chyli, Lymphaque, necnon Sanguinis——miscelam. 11. Ad conciliandum sanguini——coccineam rubedinem, &c. 12. Nec merosè negabimus, aërem——pulmones, & sanguinem illos transcurrentem, minùs calida reddere, &c. 13. Quod denique aër sanguini singulis Respirationibus aliquantillâ sui parte, admixtus, paucissimas quasdam in spiritum animalium elaboratione particulas simul contribuat. All these Uses, although of great Consequence, yet he thinks rather conduce to the Well-Being, than the Being of the Animal; because without any of them, the Animal would not so speedily die, as it doth by Strangling, or in the Air-Pump. He therefore assigns a 14ᵗʰ, and the principal Use of Respiration to be, For the passing of the Blood through the Lungs, that is thrown into them by the Heart. Etmull. Dissert. 2. c. 10. §. 1. & 16.

But the late Dr. Drake, with great Ingenuity and Address, (like a Person so considerable for his Years, as he was in his Time,) not only establish’d this Notion of Respiration, but also carries it farther, making it the true Cause of the Diastole of the Heart; which neither Borelli, Lower, or Cowper, much less any before those great Men, have well accounted for. That the Heart is a Muscle, is made evident beyond all doubt by Dr. Lower. And that the Motion of all Muscles consists in Constriction, is not to be doubted also. By which means the Systole is easily accounted for. But forasmuch as the Heart hath no Antagonist-Muscle, the Diastole hath puzzled the greatest Wits. But Dr. Drake with great Judgment, and much Probability of Reason, maketh the Weight of the Incumbent Atmosphere to be the true Antagonist to all the Muscles which serve both for ordinary Inspiration and the Constriction of the Heart. The Particulars of his Opinion may be seen in his Anatomy, l. 2. c. 7. And in Philos. Trans. 281.

And I remember when I was at the University, my most ingenious and learned Tutor Dr. Wills, when he read Anatomy to us, was of Opinion, that the Lungs were blown up by the Weight of the incumbent Air, and represented the manner of Respiration in this manner, viz. He put a Bladder into a Pair of Bellows, turning back the Neck of the Bladder, and tying it fast, so that no Air might enter in between the Bladder and Bellows. This being done, when the Bellows were opened, the Bladder would be blown up by the Weight of the incumbent Air; and when shut, the Air would be thereby pressed forcibly out of the Bladder, so as to blow the Fire. This Experiment I take Notice of here; because (besides the Illustration it gives to Respiration) that great Genius seems to have had a truer Notion of this Phænomenon, than was very common then, viz. about the Year 1677 or 78; as also, because I have in some Authors met with the same Experiment, without mention of Dr. Wills, whose I take it to have been.

Another Use of great Consideration, the already commended Dr. Cheyne assigns; namely, to form the elastick Globules of which the Blood principally consists, without which there would be a general Obstruction in all the capillary Arteries. Cheyne’s Phil. Prin. of Nat. Rel. or Harris’s Lex. Tech. in Lungs.