"All are agreed," says our author, "that one of the ventricles is the instrument of alimentation, the other the instrument of the vital spirit; the former being characterized by anatomists as the sanguineous, the latter as the spirituous ventricle. That the two ventricles pulsate at the same moment, may be seen by laying open the chest of a living animal; but they do not contain blood and spirit in the same proportion; the right having a much larger charge of blood relatively to its charge of spirit than the left, which may be said to contain the substance of the spirit.

"That the arteries contain blood and when wounded discharge nothing but blood, no one will deny who has seen one of them divided. They therefore who with Erasistratus maintain that the arteries contain air, are forced to admit that they must have communications or anastomoses with the veins, and that the veins have thus a share of spirit." In so important a light does Galen see this subject that he returns to it in a special book in which he combats Erasistratus and those who follow him, saying: "When an artery is wounded we always see blood escape; wherefore one of two things: Blood is either contained in the arteries immediately, or it flows into them from somewhere else. But if from elsewhere, it is obvious that the arteries in their natural state should contain spirit only. Were this the case, however, we should see

1" Hæ duæ vasorum genera mutuis anastomosibus inter se juncta venasque aliqua ex parte spiritus esse participes." (Ib., cap. 21.)

spirit escape from a wounded artery as a prelude to any flow of blood; but as nothing of the kind occurs we conclude that the vessel never contained aught but blood."1

Again he says: "If we lay bare an artery, include a portion of it between ligatures, and then open it, we shall find it full of blood." And yet again: "But how, say the followers of Erasistratus, if the arteries contain blood only, does the air we take in when we breathe reach every part of the body? To whom we reply wherefore the necessity of its doing so, when all that is taken in is returned again? Many therefore, and among these some of the most able both of our philosophers and physicians, have seen that the heart requires not air in substance, but coolness only, whereby it is refreshed-and this is the purpose of Respiration"-another of the Galenical, and still more ancient errors, that was only dissipated by the progress of modern chemistry, the discovery of oxygen by Priestly, and the theory of combustion announced by Lavoisier. Albert Haller, the most learned anatomist and physiologist of his age (Elementa Physiologiæ, 1757), retained a lingering belief

1 "Quoniam arteria quocunque vulnerata sanguinem egredi videmus, duorum alterum sit oportet: vel in arteriis sanguinem contineri, vel aliundè ipsum in eas confluere. Quod si aliundè, manifestum cuique est, cum se naturaliter arteriæ habebant [ut dictum est], spiritum ipsas solummodo contenuisse, oportebat in vulneratis priusquam sanguis egrederetur spiritum exire conspiceremus. Cum hoc autem fieri non videamus, nec anteà solum spiritum in arteriis contentum fuisse colligemus. (Lib. An sanguis in arteriis naturâ contineatur ?)

that the purpose of Respiration was to cool the heart.

"The reason why there are two orders of vessels in the animal body," says the great man of Pergamos, "is that the several parts may be supplied with the kind of nutriment appropriate to them. What so absurd as to suppose that the dense and heavy liver should have nourishment of the same kind imparted to it as the light and spongy lungs? Hence it is, that we see the liver furnished almost exclusively with veins, whilst the lungs are provided in large proportion with arteries. Let us, therefore, admire the providence of nature which ordains a two-fold order of vessels, but arranges mutual openings between the terminations of neighbouring branches of each." 2

Nor is this by any means the only place in which such communications between arteries and veins are spoken of. In one especially it is said that the blood, thrown by the heart into the aorta, being prevented from returning into the ventricle by the semilunar valves at its root, communicates by innumerable

1 Non oporteat eodem alimento partes omnes corporis ali. Si enim unicum esset duntaxat sanguinis vas, simili partes omnes alerentur nutrimento; quo quid absurdius dici potest quam ut similem ad sui nutritionem postulent sanguinem, verbi gratia, hepar, viscerum omnium gravissimum et densissimum, et pulmo lævissimus ac rarissimus. Proinde rite a natura factum est ut non arteriæ modo, verum etiam venæ in animalium corporibus inessent. (De usu Partium, lib. vi., cap. 17.)

2 "Simul ipsorum fines sibi ipsis vicinos mutuis inter se orificiis aperuit atque applicuit." (Ib.)

D

anastomoses with the veins, to the end that they may participate in the vital spirit with which the arteries are especially charged. That there was the freest possible communication between the arteries and veins of the body, was indeed perfectly well known to Galen. The two orders of vessels, he says, anastomose or inosculate by means of certain minute and invisible passages; so that if a large artery be divided, both arteries and veins are alike and rapidly drained of their blood—a fact which he had ascertained experimentally.2

In the transfusion which is thus shown to take place, the arteries by their dilatations are said to suck in from the veins, and by their contractions to return to them what they had taken.3

These matters are seen by our author to be of such moment that they are reverted to and discussed in another work, in which all that is said above is repeated in other words: "If you kill an animal by dividing one or more of the larger arteries, you will find the veins as well as the arteries of the whole

"In toto corpore mutua est anastomosis atque osculorum apertio arteriis simul cum venis; transumuntque per invisibiles quasdam atque angustas plane vias.” (Ib., vi., 10.)

2 "Arteria magna vulnerata universum animalis sanguinem per eam exhauriret. Hujus rei periculum fecimus subinde; et quum semper vacuatas cum arteriis venas deprehendissemus, verum esse dogma de communibus arteriarum et venarum osculis nos persuasemus." (Ib., lib. v., cap. 5.) The two orders of vessels, he goes on to say, do, in fact, communicate freely throughout the body.

366 Quippe per hos transitus arteriæ dilatatæ ex venis trahunt; contractæ contra, in eas regerunt." (Ib., v., 5.)

body emptied of their blood; but this could not happen did not the two orders of vessels inosculate."

"The heart is ceaselessly in motion from the beginning of life to its close; the principal motion being the diastole, which is ascribed to the innate heat of the organ: As the bellows of the blacksmith draw in air when they are expanded, as the flame of the lamp draws oil to it through the wick, or as the magnet (lapis Heraclius) attracts iron, so is it with the heart it possesses in itself an inherent power of attraction; so that even as air is drawn into the lungs by the expansion of the chest in breathing, is the finer part of the blood attracted from the right to the left ventricle of the heart by its diastole, the partition between them having certain minute pores or orifices to this end designed. These indeed are seen with difficulty in the dead body, the parts being then cold, hard and rigid. Reason assures us, however, that such pores must exist. Nature does nothing imperfectly or in vain, and it is not by accident that these passages lie so deeply, or end by such inconspicuous orifices. Besides these pores, however, there are two mouths-duo ora-in the right ventricle, one by which the blood is brought into the heart; another by which it is sent out to the lungs.'

"2

"But all the blood thus intromitted is not for the

1" Quod sane nunquam fieret nisi inter se haberent altera in alteram ora reclusa." (De Natura Facult., iii., 15.)

2 "Quorum quidem alterum sanguinem in ipsum cor intromittet, alterum autem ex ipso in pulmonem deducit." (Ib., lib. i., cap. 7.)