william harvey and the pulmonary circulation

William Harvey and the Pulmonary CirculationAuthor(s): Donald FlemingSource: Isis, Vol. 46, No. 4 (Dec., 1955), pp. 319-327Published by: The University of Chicago Press on behalf of The History of Science SocietyStable URL: http://www.jstor.org/stable/227574 .

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William Harvey and

the Pulmonary Circulation

By Donald Fleming *

IT is customary to represent William Harvey as the culminating figure in a rebellion against the Galenical motions of the blood - particularly in the

heart and lungs.' A line is often traced from Vesalius as the first to deny that there were pores in the interventricular septum of the heart through which blood could pass, as Galen claimed, directly from right to left. Michael Servetus and Realdo Colombo are then said to have found in the pulmonary circulation an alternative to passage through the septum. To this contribution the work of Fabricius of Aquapendente in calling general attention to the venous valves is added as a final element in preparing the way for Harvey.2 Whatever may be thought of the last point, one can say with some assurance that neither the overthrow of Galen's teaching on the motions of the blood in the heart and lungs nor the establishment of the pulmonary circulation was a decisive element in Harvey's achievement.

Galen's doctrine in this matter was much nearer to the truth than is com- monly believed.3 Though he mistakenly allowed for the passage of some blood from the right ventricle to the left through pores in the septum, he knew that much, if not most, of the blood in the right ventricle passed into the "arterial vein" (our pulmonary artery) in the direction of the lungs. He also provided for the passing over of blood in the lungs from the venous into the arterial system (in our terminology, from the arterial into the venous). What exactly was borne into the left ventricle by the "venous artery," corresponding to our pulmonary veins, Galen failed to make clear. The chief strength of his account lay in his description of the four sets of cardiac valves which impose one-way traffic in the ventricles. He did, however, fall into the error of supposing that the mitral valves guarding the entrance into the left ventricle functioned im- perfectly and allowed sooty wastes to move backward from the heart to the lungs, against the prevailing current. In spite of this lapse, Galen may fairly be

* Department of History, Brown University. 1 Cf., e.g., A. R. Hall, The Scientific Revolu-

tion z500o-800 (London, 1954), ch. V. 2 Cf. Robert Boyle, A Disquisition about the

Final Causes of Natural Things, i688; in Works, ed. Thomas Birch, 2d ed. (London, 1772), V, 427: "And I remember, that when I asked our famous Harvey, in the only discourse I had with him, (which was but a while before he died) what were the things, that induced him to think of a circulation of the blood? he answered me, that when he took notice, that the valves in the veins of so many parts of the body were so

placed, that they gave free passage to the blood towards the heart, but opposed the passage of the venal blood the contrary way; he was in- vited to imagine, that so provident a cause as nature had not so placed so many valves without design; and no design seemed more probable, than that since the blood could not well, because of the interposing valves, be sent by the veins to the limbs, it should be sent through the arteries, and return through the veins, whose valves did not oppose its course that way."

'Cf. Donald Fleming, "Galen on the Motions of the Blood in the Heart and Lungs," Isis, 1955, 46: 14-21.

3I9



320 DONALD FLEMING

said to have opened a channel through the lungs by which blood might flow from the right ventricle to the left but never in reverse. If the pores in the septum were once stopped up, this channel would have to be invoked as the only possible means of transfer.

In a sense, however, what Galen really said about the pulmonary circulation is immaterial for the present purpose. One need only know what Harvey took him to be saying. Harvey addresses himself to this point twice in the course of De Motu. In chapter 5, he discusses the passage in De Placitis Hippocratis et Platonis in which Galen says that the arteries carry spirits and that there is no vessel by which purified blood can be distributed from the heart to the rest of the body.4 As Harvey says, Galen elsewhere establishes, against the very Erasistrateans with whom he is contending in this treatise, that the arteries carry not spirits but blood; and his discussion of the semilunar valves indicates that the aorta is the great distributing vessel in question.5 Why then, Harvey asks, has Galen fallen into error in this instance? "Does he hesitate, as all after him to the present, because he could not see, on account of the close connection between heart and lungs, a way by which blood might go from veins to arteries?" 6 The clear implication is that Galen has been pulled up short by the implausibility of a pulmonary circulation.

It must be borne in mind, however, that Harvey is here accounting for a single aberrant passage. In chapter 7, where he brings together the best of the Galenical writings on the subject, the tone is entirely different. Here Harvey actually seems at one point to be claiming for Galen full and explicit knowledge of the pulmonary circulation: ". . . this truth may be confirmed by the words of Galen himself, that not only may blood be transmitted from the arterial vein to the venous artery, then into the left ventricle, and from there to the arteries, but that this is accomplished by the continual beat of the heart and the motion of the lungs in breathing." 7 At first glance this gives every appearance of having been intended as an epitome of Galen's own teaching. If, however, one

' Exercitatio anatomica de motu cordis et sanguinis in animalibus (Francofurti, I628), pp. 31-32; Guilielmi Harveii Opera Omnia, ed. Mark Akenside ([London], I766), pp. 35-36. The original passage may be found in Claudii Galeni De Placitis Hippocratis et Platonis, lib. 6, cap. vi; ed. Iwanus Muller (Lipsiae, I874), I, 541-542 (Opera Omnia, ed. C. G. Kuhn, V, 550-551): "clpa gaw0ev 9w pE7rowTas 77 ToPvarTrov

Qw0ev gaw O/epoALefvovs; dXX&a 'gaws o0e TOUTO .ueeya 7rpOs TO 7rpo7rapeCaKeVacOaL /uev ev v7raT TO r a,/Aa,

q/YpecfaaL 5U evTerOev es T*P Kap5Biav voX+'6ie,vov gpTaVOa TOr Xe7rop TriS OIKedas 156as es dKpL/i TeXeL6T67Ta. Kai yap Kai X6yoo gXe, r/OV75 T7VP TeXeCVJ Te Kai /LAcydXCv gp-ywv dipops 56Jvaa0a PyeveTOat /uL756 Jc' eVoS 6p-yv PO qaLKoV TOVP OLKeCoP K6aLuov a7rapTa KTfraaaOaL. 5eEaTe ouvp

J,uEv CeTepov dyyeclov eCYov 9K T-rS Kap5tas TOvTr TOr KOaE7T0/ev at,/ua KaEZ 5Lave/L6/Levov es a'7rav T7O

a04,ua, KaOci7rep j dpT77pta TO 7rJemvua." 6"Si quis vero ibidem pro Erasistrato, vel

pro illa, & nunc nostra opinione (ipsius con- fessione Galeni) alias rationi consentanea instaret, & arteriam magnam sanguinem 6 corde in universum corpus dispensantem digito com-

monstrasset; Quid divinus ille vir ingeniosissimus & doctissimus responderet, miror. Si arteriam spiritus dispensare & non sanguinem diceret; profecto Erasistratum refelleret satis (qui in arteriis spiritus duntaxat contineri arbitrabatur) sed sibi ipsi contradiceret interea & id esse turpiter negaret, quod libro proprio acriter esse contendit, contra eundem Erasistratum: & multis, & validis argumentis comprobat, & ex- perimentis demonstrat, quod sanguis contineatur in arteriis natura, & non spiritus." De Motu, 31-32; Opera Omnia, 35-36.

"An adhuc forsan haesitaret, ut omnes in hunc usque diem post ipsum, quod propter contextum, ut dixi cordis cum pulmone, non videat vias, per quas sanguis e venis in arterias transferri possit." De Motu, 32; Opera Omnia, 36. Translation by Chauncey D. Leake (Spring- field, Ill., 1928), p. 5I. All subsequent transla- tions from De Motu are from Dr. Leake; but I have systematically substituted "arterial vein" for his "pulmonary artery," and "venous artery" for his "pulmonary vein." I have also made a few minor changes.

7 "Sed quando aliqui sunt, qui nil nisi



HARVEY & THE PULMONARY CIRCULATION 321

studies the citations from Galen which follow, one finds that none of these con- tains a clear statement of the pulmonary circulation.8 Moreover, Harvey's own summing-up of the force of the passages which he has quoted from Galen is equivocal:

From the words of that great Prince of Physicians, Galen, it seems clear that blood filters through the lung from the arterial vein to the branches of the venous artery as a result of the heart beat and the movement of the lungs and thorax. The heart, further, continually receives blood in its ventricles, as into a cistern, and expels it. For this reason, it has four kinds of valves, two regulating inflow, and two outflow, so blood will not be inconveniently shifted back and forth like Euripus, neither flowing back into the part from which it should come, nor quit- ting that to which it should pass, lest the heart be wearied by vain labor and respiration be impeded. Finally, our assertion is clearly apparent, that the blood continually flows from the right to the left ventricle, from the vena cava to the aorta, through the porosities of the lung.9

In the one sentence which expressly claims to give the views of Galen himself, the blood is not said to have passed through the venous artery into the left ventricle, but merely from the venous system of the lungs into the arterial. One is therefore led to ask whether Harvey was conscious of a weakness in Galen's doctrine at this point. The only additional evidence which seems to be available may be found in the early pages of De Motu. There, in setting forth the misguided opinions with which he has to contend, Harvey makes fun of currents flowing in opposite directions through the mitral valves of the left ventricle; and the inflowing current of which he speaks is air, not blood.10 It must be admitted that Harvey does not explicitly identify this orthodoxy with Galen himself. If, however, one accepts the identification and takes it as a gloss on chapter 7, one may well conclude that in Harvey's considered opinion Galen had not postulated a pulmonary circulation of which the end result was to thrust blood into the left ventricle. Here he would be in accord with the best opinion of historians of science. The real tribute paid by Harvey to Galen would then consist in an acknowledgment that Galen by his description of the

adductis authoritatibus admittunt; iidem ex ipsius etiam Galeni verbis hanc veritatem con- firmari posse sciant; scilicet non solum posse sanguinem, e vena arteriosa in arteriam venosam, & inde in sinistrum ventriculum cordis, & postea in arterias transmitti: sed ex continuo pulsu cordis, & pulmonum motu inter respirandum, hoc fieri." De Motu, 38; Opera Ontnia, 44; Leake, 63.

'De Motu, 38-39; Opera Omnia, 44-46. The passages from Galen are cited from the originals in Fleming, "Galen."

"Ex Galeni igitur viri divini patris Medi- corum locis & verbis clare apparet, & sanguinem per pulmones de vena arteriosa, in arteriae venosae ramulos permeare, tum propter pulsum cordis, tum propter pulmonum & thoracis motum. Quinetiam quod cor continue in ven- triculos quasi lacunam, recipere & emittere sanguinem, & huius rei causa valvularum genera quatuor, duo introductioni, emissioni sanguinis duo inservire; ne aut sanguis Euripi in morem

inconvenienter agitetur, huc, illuc, aut retro remearet, unde trahere praestiterat, & ex illa reflueret parte, ad quam mittere erat necesse. Et sic cor vano labore fatigaretur, & pulmonum respiratio praepediretur. Denique clare apparet assertio nostra, continue, & continenter sanguinem per pulmonum porositates permeare de dextro in ventriculum sinistrum, de vena cava in arteriam magnam. [Ad marg.: Vide Hof- manni doctissimi Commentarium supra Galeni lib. 6 de usu part. Quem librum post quam haec a me scripta essent vidi.]" De Motu, 39-40; Opera Omnnia, 46; Leake, 65-66.

10 ". quomodo dicunt per arteriam venalem spirituosum sanguinem distribui e ventriculo sinistro in pulmones, nec interim impediant tricuspides? cum affirmarint aerem per idem vas a pulmonibus in ventriculum sinistrum ingredi, cuius regressui tricuspides filae valvulae [Aken- side: illas valvulas] impedimento esse voluerunt. Deus bone! Quomodo tricuspides impediunt aeris egressum [Akenside: regressum], & non sanguinis." De Motu, i6; Opera Omnia, i6.



322 DONALD FLEMING

cardiac valves and of the anastomosis of veins and arteries in the lungs had afforded conclusive evidence of such a circulation for those who cared to see. This in itself is a remarkable tribute from the 17th century to the 2nd, and one which follows not from the most generous but from the most conservative estimate of the comfort taken by Harvey from Galen's writings.

Thus Galen's conception of what happened to the blood in the heart and lungs did not obstruct Harvey's work. Moreover, this is true in a double sense. For even if Galen had had in Harvey's view no glimmering whatever of the anatomical basis of the pulmonary circulation, this would not have made any decisive difference to Harvey. So long as Galen, or anyone else, acknowledged that there was a one-way valve admitting blood to the right ventricle and another such valve discharging it from the left, Harvey could rest content. For on this basis a systemic circulation could be established, and at bottom this was the only thing that Harvey was interested in. If, as Galen never claimed, the whole of the blood in the right ventricle had passed through the septum, the basic structure of Harvey's thought would have been totally un- impaired. At least once, in his letter to Slegel of I65I, he himself spelled the point out in unmistakable terms. The younger Riolan of Paris "vaunts himself on having upset the very foundations of the Harveian circulation" by sending blood through the septum. But "I have nowhere assumed such a basis for my doctrine, for there is a circulation in many red-blooded animals that have no lungs." 11

Now, this statement as such might be regarded as a mere stratagem of debate, got up for polemical purposes long after the event. If, therefore, the point is to carry conviction, one must look to the text of De Motu itself and ask what Harvey had to say about the pulmonary circulation, not in 1651 but in I628. The principal defense of the pulmonary circulation occurs in chapters 6 and 7. With one possible exception, these have given less satisfaction than any other part of the book. Dr. Leake finds them "puzzling," with " a peculiar use of the traditional authority of Galen as evidence." 12 Professor Woodger in his logical analysis of De Motu finds much of these chapters anomalous in lacking any direct experiential basis. "Harvey's argument here is largely a propaganda argument - a use of persuasion rather than an appeal to reason." 13

In brief, Harvey's central vindication of the pulmonary circulation in De Motu is a tissue of analogies and authorities. The description of cardiac valves is drawn from Galen; and "the passage of blood through the substance of the lungs from the right ventricle of the heart to the venous artery and left ventricle" is commended by analogy with other processes in nature. "That this

' To P. M. Slegel of Hamburg; London, 26 March I651: "Interea temporis, quoniam Riolanus summo molimine id agit, ut sanguini per pulmones, in sinistrum cordis ventriculum, transitum praecludat, eumque omnem illuc per septum deducat, eoque pacto circulationis Har- veanae fundamentum penitus eversum iri gloria- tur (licet id a me pro fundamento circulationis meae nuspiam statutum sit; sit enim sanguinis circuitus in plurimis animalibus sanguineis, in

quibus pulmones nullos reperias) libet hic experimentum &/VKTroP, a me nuper et collegis aliquot praesentibus exploratum, commemorare." Opera Omnia, 6I3; translation by Robert Wil- lis, The Works of William Harvey (London, I847), 597. Note that in this letter of his old age Harvey describes a conclusive experimental demonstration of the pulmonary circulation.

12 Leake, "Translator's Postscript," 137. 13J. H. Woodger, Biology and Language

(Cambridge, Eng., 1952), 92.




may be so, and that there is nothing to keep it from being so, is evident when we consider how water filtering through the earth forms springs and rivers, or when we speculate on how sweat goes through the skin, or urine through the kidneys." 14

Though the prevailing note of this part of De Motu is to cite somebody else and some other process, Harvey does say at one point that he and Realdo Colombo consider the pulmonary circulation evident "from dissections and other reasons given previously." 15 The other reasons are not repeated, and can only be deduced from the content of earlier chapters. The critical point would seem to be the fact, already known to Colombo and experimentally demonstrated by Harvey himself, that the two ventricles contract and dilate in unison.'6 On this ground Harvey finds it hard to see how the right ventricle in systole could contrive to thrust blood into the left ventricle, also in systole. Even if the pores are there, he asks, "how could the left ventricle draw blood from the right when both ventricles contract and dilate at the same time?" 1' This argument would naturally fall to the ground if one held that the left ventricle was never gorged with blood and by contrast with the right was comparatively empty even in systole. Harvey's observations had shown, however, that such a view was untenable.

One finds, therefore, that early in De Motu Harvey gives in a single sentence a cogent argument, grounded in experiment, in support of the transit of blood through the lungs. Yet this argument is neither expanded nor even repeated in passing when Harvey gets to the point in his analysis where this would be appropriate. He had the means to make his defense of the pulmonary circulation in chapters 6 and 7 fresh from the mint of his own mind. Instead he made it second-hand and almost renunciatory. In such a man, at the height of his powers, this can scarcely have been an accident. The "unsatisfactory" nature of this part of the book may therefore be taken as an index of Harvey's comparative indifference to the pulmonary circulation.

The fact is that though well aware of its existence in many animals, he scarcely knew what to make of it. Here he made contact with the problem of the purpose subserved by circulation in general.'8 His own view was that by the coursing of blood through the body, "all parts are fed and warmed." In the process the blood itself is "cooled, thickened, and loses its power, so that it returns to its source, the heart, the inner temple of the body, to recover its

14isFieri autem hoc posse, & nihil esse, quo minus fiat, satis constat, cum & quomodo [Aken- side: cum quomodo] aqua per terrae substan- tiam permeans, rivulos, & fontes procreet, con- sideremus [Akenside: consideramus], aut quomodo per cutem sudores: per parenchyma renum, urina fluat, speculamur." De Motu, 37; Opera Omnia, 42; Leake, 6i.

15De Motu, 38; Opera Omnia, 44; Leake, 63- "ex ante dictis, & autopsia, aliisque argumentis."

i "Pace tantorum virorum [ad marg.: Bauhin. lib. 2. C. 21. Ioan. Riolan. lib. 8. cap. i.j, quatuor sunt motus, loco, non vero tempore

distincti. Simul enim ambae auriculae movent, & simul ambo ventriculi, ut quatuor loco motus distincti sunt [Akenside: sint] duobus tantum temporibus, atque hoc se habet modo." De Motu, 26; Opera Omnia, 28.

17 De Motu, i8; Opera Omnia, 17; Leake, 21 -"Sed si adessent foramina, quomodo (cum simul uterque ventriculus distenditur, & dilata- tur) [Akenside: distendatur, dilatetur] alterum ab altero quidpiam, aut sinistrum sanguinem l dextro exhaurire possibile est?"

18 On this whole subject, see the brilliant book by John G. Curtis, Harvey's Views on the Use of the Circulation of the Blood (New York, 1915).



324 DONALD FLEMING

virtue." 19 In this context he draws his famous analogy with the meteorological cycle of Aristotle, with the heart as "the sun of the microcosm." Harvey's explanation, if any, of the purpose served by the pulmonary circulation must fit into this larger scheme. Discussions of the function of breathing had tradi- tionally stressed the cooling effect of the air, and Harvey himself fell back on this point. Why is the blood filtered through the lungs in the larger, adult animals? "It may be that the larger, more perfect animals are warmer and when full grown their greater heat is thus more easily damped. For this reason the blood may go through the lungs, to be cooled by the inspired air and saved from boiling and extinction." 20 If this explanation were adopted, Harvey would be saying that the heart consistently warms the blood to excess so that only the cooling effect of air in the lungs keeps it from boiling away. In his effort to account for the pulmonary circulation, he has been brought to the verge of acknowledging that the much-vaunted animal economy invariably overshoots the mark in the heart and has to retrieve itself in the lungs. No wonder he says that there may be other reasons why the blood goes through the lungs. But what these are he never specifies. Only if he had understood the purpose of the circulation as we do could the pulmonary transit have taken on decisive importance in his doctrine. In the circumstances, it always re- mained for him at best secondary and at worst positively embarrassing. The embarrassment ought not, however, to be exaggerated. He rightly felt that doubts about the purpose which nature had in view could not touch his central achievement, to have set forth the fact of the circulation. "I own I am of opinion that our first duty is to inquire whether the thing be or not, before asking wherefore it is." 21

A more fundamental explanation of Harvey's comparative indifference toward the pulmonary circulation than his uncertainty concerning its purpose may be found on the very title-page of De Motu. He called the book, advisedly, a treatise on the motion of the heart and blood in animals. He undertook to treat not of men alone but of animals in general. This purpose is borne out by the whole text of De Motu and most explicitly by chapters 5 and 6. Here he points out that the general motion of the blood is obscured by the presence in man and some other animals of a pulmonary circulation. "The chief cause of perplexity and error in this matter seems to me to be the close connection between the heart and lungs in man. When both the venous artery and the arterial vein were seen to disappear into the lungs, it was very puzzling to de- termine how the right ventricle might distribute blood to the body or the left

" "Sic verisimiliter contingat in corpore, motu sanguinis, partes omnes sanguine calidiori perfecto, vaporoso, spirituoso, (& ut ita dicam) alimentativo, nutriri, foveri, vegetari: Contra in partibus sanguinem refrigerari, coagulari, & quasi effaetum reddi, unde ad principium, videlicet, Cor; tanquam ad fontem sive ad lares corporis, perfectionis recuperandae causa, revertitur. ..." De Motu, 42; Opera Omnia, 49; Leake, 7'i.

?". . . sive hoc sit quod majora, & per-

fectiora animalia sint calidiora, & cum sint adulta, eorum calor magis (ut ita dicam) igniatur & ut suffocetur sit procivis: Ideo tranare, & traiici per pulmones, ut inspirato aere contemperetur, & ab ebullitione, & suffocatione vindicetur, sive quid aliud tale." De Motu, 36; Opera Omnia, 41-42; Leake, 59.

2 Exercitatio anatomica de circulatione sanguinis, I649; cited from Opera Omnia, 122 (Willis, 123) - "Prius in confesso esse debet, quod sit, antequam propter quid, inquirendum.




draw blood from the vena cava." 22 This has seemingly led even Galen to "hesitate" before the truth and has hardened many lesser men in error.

Happily, many of the lower animals do not have a pulmonary circulation. In them the basic issue of the systemic circulation can be studied without any distracting complications. Fishes, toads, frogs, serpents, and lizards have only one ventricle.

It is obvious in opening these animals that the blood is transferred from the veins to the arteries by the heart beat. The way is wide open; there is no difficulty or hesitancy about it; it is the same as it would be in men were the septum of the heart perforated or removed, making one ventricle of the two. Were this so, no one would doubt, I think, how blood passes from veins to arteries.23

Moreover, even the lung-animals do not breathe in foetu, and here also the perplexities of the pulmonary circulation can be avoided.24 Indeed, the very structure of the foetal heart and blood vessels is designed to bypass the lungs. Thus Harvey conceives of the foramen ovale in the foetus as allowing blood to pass directly from the vena cava to the venous artery - an error, for the foramen opens into the left auricle itself - and, correctly, of the ductus arteriosus as transporting blood from the arterial vein into the aorta.25

In Harvey's opinion many anatomists had been led into error about the pulmonary circulation by failing to study the simpler structures and processes of lower animals. But even if no confusion had ever ensued, these men would still have been at fault.

. . . the common practice of anatomists, in dogmatizing on the general make-up of the animal body, from the dissections of dead human subjects alone, is objection- able. It is like devising a general system of politics, from the study of a single state, or deigning to know all agriculture from an examination of a single field. It is fallacious to attempt to draw general conclusions from one particular proposition.26

The offense of his fellow-workers in Harvey's eyes was nothing less than to 22 "Causa maxima hac in parte haesitandi,

& errandi una fuisse mihi videtur, cordis cum pulmone in homine contextus: cum venam ibi arteriosam in pulmones obliterari, & similiter arteriam venosam conspexissent, unde aut quomodo dexter ventriculus in corpus distri- bueret sanguinem: aut sinister e vena cava exhauriret, obscurum admodum illis erat.... De Motu, Pi; Opera Omnia, 35; Leake, 50.

a "Idem etiam deinde in omnibus animalibus, in quibus unus duntaxat ventriculus, vel quasi unus, non diffcile est cernere, ut in bufone, rana, serpentibus, lacertis, . . . ex autopsia eodem modo in illis e venis in arterias sanguinerm pulsu cordis traductum esse palam est, & via patens aperta, manifesta, nulla difficultas, nullus haesitandi locus: In his enim perinde se res habet atque in homine, si septum cordis perforatum, aut ademptum esset, aut unus ex utrisque fieret ventriculus, quo facto, nemo credo dubitasset, qua via sanguis e venis in arterias transire potuisset." De Motu, 33; Opera Omnia, 37-38; Leake, S4.

2'De Motu, 33-36; Opera Omnia, 38-4I.

'De Motu, 34; Opera Omnia, 38-39. In the modern view, most of the blood from the superior vena cava passes, by way of the right auricle, into the right ventricle and thence through the pulmonary artery and ductus arteriosus to the aorta (with some blood going to the lungs and thence passing through the pulmonary veins to the left auricle); most of the blood from the inferior vena cava empties almost directly into the left auricle via the foramen ovate and from there passes into the left ventricle and out into the aorta. There is thought to be some confusion of the two streams.

"In hoc peccant, qui dum de partibus animalium (uti vulgo omnes Anatomici faciunt) pronunciare, & demonstrare, aut cognoscere volunt, unum tantum hominem, eumque mortuum introspiciunt, & sic tanquam, qui una reipub[licae] forma perspecta disciplinam poli- ticam componere, aut unius agri naturam cog- noscentes, agriculturam se scire opinantur: Ni- hilo plus agunt, quam si ex una particulari propositione, de universali Syllogizare darent operam." De Motu, 32-33; Opera Omnia, 37; Leake, 53.



326 DONALD FLEMING

have mistaken the universe of discourse. He for his part took for granted that it was the anatomist's task to elucidate not any one circulation of the blood but all circulations, including the foetal. The assumption is profoundly gratu- itous, in the way that all the great commitments of life must be, and corre- spondingly significant for his own character and temperament. Though many anatomists had certainly made incautious transfers of knowledge from one animal to another (generally, however, from lower animals to man and not, as Harvey states, vice versa), there is no evidence that most of Harvey's con- temporaries were attempting to produce the anatomical equivalent of "a general system of politics." The only person who is consciously dealing with "the general make-up of the animal body" is Harvey himself. In fact he has transferred to others his own really imperial ambition, to comprehend the whole animal kingdom within a single field of vision. The same ambition may be seen at work in his other great book, De Generatione Animalium (I65I), from the frontispiece illustration of Jove opening an egg from which a mixed assortment of animals (and plants) spring forth, through the use of the word animals in the title, to the characteristic statement that after studying generation in the main types of animals "we may turn to the consideration of the more abstruse nature of the vegetative soul, and feel ourselves in a condition to understand the method, order, and causes of generation in animals generally." 27 In fact, they all took their first beginning from an egg.28 For Harvey, synoptic views of this kind were not simply the means to some further end, such as the better understanding of particular animals, but the end in itself. He was a comparative anatomist who sought for an ideal common pattern beneath the diversities of concrete existence. He did not of course make this a pretext for inaccuracy. He clearly wished in De Motu, not to deny or misrepresent the details of particular circulatory systems, but merely to transcend and comprehend them in a larger scheme. In this view, knowledge of the pulmonary circulation, where one existed, was important for Harvey only as a warrant that in his search for a generalized conception of the circulation he had not lost his grip on concrete realities.

Yet the warrant was worth having. For almost by definition Harvey's own peculiar temptation would be to let go of realities and hold fast to general con- ceptions. This is precisely what happened when the idea of a lymphatic system began to emerge at the end of Harvey's life - the fitting complement, as many people thought, to his own work, but to him anathema. Attention was first focused on the lacteals, the lymphatic vessels which carry chyle - emulsified fat - from the small intestines to the veins by way of the thoracic duct. "But how," Harvey wrote apropos of the researches of Jean Pecquet of Dieppe, "how can these vessels serve as conduits for the whole of the chyle, or the

2 Exercitationes de generatione animalium, I65I; cited from the presumed second edition (Amstelodami, Apud Ludovicum Elzevirium, I65i), 34 (Opera Omnia, I79; Willis, i65)- "His perspectis, & cognitis, naturam animae vegetativae abstrusam contemplari; & in omnibus animalibus, generationis modum, ordinem,

atque causas intelligere licebit. ..." ' De Generatione, 38; Opera Omnia, I82;

Willis, 170 -"Nos autem asserimus, (ut ex dicendis constabit) omnia omnino animalia, etiam vivipara, atque hominem adeb ipsum ex ovo progigni; primosque eorum conceptus, e quibus foetus fiunt, ova quaedam esse; ut & semina plantarum omnium."



OXYGEN & PHLOGISTON THEORIES IN U.S. 327

nourishment of the body, when we see that they are different in different animals?" 29 He himself could find no trace of lacteals in birds and fish. "Nor do I see any reason why the route by which the chyle is carried in one animal should not be that by which it is carried in all animals whatsoever." 30 Harvey had made himself immortal by a generalized conception of the circulation; he had done important work on generation in the same spirit; and he could not conceive why the physiology of nutrition should not make up a triumvirate of vital processes substantially the same throughout nature.

To account for Harvey's attitude toward the pulmonary circulation, one must therefore penetrate to the very core of his thought and personality. One finds a habit of mind which leaves him cut off at both ends of time - not really the successor of Vesalius and Colombo on the pulmonary circulation, and not willingly the precursor of Pecquet and Bartholin on the lymphatics. He had an instinct for simplicity in thought and isolation in history. This instinct could and did lead him astray, but rightly told him that the pulmonary circulation was not central for his purpose.

9 Letter to R. Morison of Paris; London, 28 April I652: "Quomodo autem toti chylo, cor- porisve nutrimento, deferendo inserviant, siqui- dem hi ductus in diversis animalibus diversi

conspiciuntur?" Opera Omnia, 622; Willis, 6o6. 'To Morison: "Neque causam ullam video

quin, quo itinere chylus in uno fertur, eodem quoque in aliis omnibus animalibus transferatur ... ." Opera Omnia, 626; Willis, 609.

An Attempt in the United States

to Resolve the Differences

between the Oxygen and the

Phlogiston Theories

By Robert Siegfried *

EFORE the arrival of Joseph Priestley in America in I794, there had not been any apparent concern among American chemists as to the phlogiston

controversy that had been taking place in Europe. Priestley had become, by that time, the last major chemical figure still maintaining an undiminished pref- erence for the phlogiston theory. But he neither found nor made any adherents

t Read before the History of Science Society, Baltimore, Maryland, 3 April I954. This paper is based upon a portion of a Ph.D. thesis sub- mitted to the graduate school of the University of Wisconsin. The author gratefully acknowl- edges the help and encouragement provided by

Professors Aaron J. Ihde and Robert C. Stauffer of the University of Wisconsin, under whose direction this work was originally under- taken.

* Department of Chemistry, University of Arkansas.



william harvey and the pulmonary circulation

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