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Book Title: On the Motion of the Heart and Blood in Animals|
Format files: PDF
The size of the: 5.53 MB
v The author of the book: William Harvey
Edition: Kessinger Publishing
Date of issue: December 1st 2005
ISBN 13: 9781425464974
City - Country: No data
Read full description of the books On the Motion of the Heart and Blood in Animals:Good God! how should the mitral valves prevent the regurgitation of air and not of blood?
I have a friend who studied history, who likes to complain how about how unfairly maligned are the Middle Ages in the popular imagination. According to him, and according to much else I’ve heard, the characterization of that time period as consisting of incorrigible dogma and the absence of all free intellectual inquiry, is simply a bunch of lies concocted in the Renaissance and perpetuated to the modern day. I have no doubt that this is true; but still, I cannot help suspecting that there is, at least, a degree of truth in the negative characterizations of the Medieval period. For example, just before reading this book, I read a work of Galen, and came away very unimpressed with the Roman physician; so it is hard not to be dismayed to find Galen’s inaccurate theories still holding sway in 1628, almost 1,500 years after Galen’s death. This strikes me as very wrong.
In any case, this book is one of the classics of European science. Harvey is a tremendously impressive man; and this book is a product of deep learning and an inquisitive mind. That the heart pumps blood, and that blood circulates away from the heart in arteries and back to the heart in veins, seems obvious; so it is fascinating and strange to see somebody trying to prove just that. That European science could have gone on so long without such a basic anatomical understanding is frightening. I wonder if this is partly due to the engrained class divisions holding sway at that time. Doctors were considered a part of the learned gentility, akin to professors of other subjects; so would they have understood the workings of the body more quickly if they spent more time with farmers and butchers? Medicine isn’t a subject that should be taught in the ivory tower, after all.
So how did Harvey arise at this insight? Well, it was difficult; in his words:
When I first gave my mind to vivisections, as a means of discovering the motions and uses of the heart, and sought to discover these from actual inspection, and not from the writings of others, I found the task so truly arduous, so full of difficulties, that I was almost tempted to think, with Fracastorius, that the motion of the heart was only to be comprehended by God.
Thankfully, that didn’t turn out to be the case. Rather, Harvey performs numerous dissections and vivisections, not only on humans, but on a variety of other species. Here we see him observing an invisible shrimp:
We have a small shrimp in these countries, which is taken in the Thames and in the sea, the whole of whose body is transparent; this creature, placed in a little water, has frequently afforded myself and particular friends an opportunity of observing the motions of the heart with the greatest distinctness, the external parts of the body presenting no obstacle to our view, but the heart being perceived as though it had been seen through a window.
In perhaps the most famous experiment included in this book, Harvey manages to resuscitate a pigeon:
Experimenting with a pigeon upon one occasion, after the heart had wholly ceased to pulsate, and the auricles too had become motionless, I kept my finger wetted with saliva warm for a short time upon the heart, and observed that under the influence of this fomentation it recovered new strength and life, so that both ventricles and auricles pulsated, contracting and relaxing alternately, recalled as it were from death to life.
Apparently, the commonly held belief, that autopsies and dissections on humans were taboo in the Middle Ages, is untrue. So what prevented doctors from figuring out how the heart worked? It wasn’t that they weren’t dissecting humans, Harvey says, but that they were confining their attention solely to humans:
Had anatomists only been as conversant with the dissection of the lower animals as they are with that of the human body, the matters that have hitherto kept them in a perplexity of doubt would, in my opinion, have met them freed from every kind of difficulty.
(As a side note, the great similarities that Harvey notes in the bodies of fish, snakes, birds, and other mammals, reveals tantalizing evidence for evolution; otherwise, it’s hard to explain why all of these apparently unrelated animals are built on the same body plan, and share the same, or analogous, internal organs.)
In another fascinating experiment, Harvey uses a ligature (a binding to decrease the flow of blood to a limb, at that time used in amputations), first on animals, and then on humans, to observe the valves in veins that prevent blood from flowing backwards. By tying the cord tightly, Harvey could see the veins on the surface of the arm; then, with his finger, he tried to push the blood backward, but it wouldn’t go; but if he tried to push it forwards, up the arm, it was moved easily.
I must admit, however, that even though some parts were absolutely fascinating, much of Harvey’s points went over my head. In order to fully understand this book, you would need, I think, both a thorough understanding of the state of medical knowledge before Harvey, as well as a thorough understanding of the heart’s anatomy—both of which I lack. Still, there are some beautiful quotes in the book, which I want to include.
Here we have his manifesto:
My dear colleagues, I had no purpose to swell this treatise into a large volume by quoting the names and writings of anatomists, or to make a parade of the strengths of my memory, the extent of my reading, and the amount of my pains; because I profess both to learn and to teach anatomy, not from books but from dissections; not from the positions of philosophers but the fabric of nature; and then because I do not think it right or proper to strive to take from the ancients any honor that is their due, nor yet to dispute with the moderns, and enter into controversy with those who have excelled in anatomy and been my teachers. I would not charge with willful falsehood anyone who was sincerely anxious for truth, nor lay it to any one’s door as a crime that he had fallen into error. I avow myself the partisan of truth alone; and I can indeed say that I used all my endeavours, bestowed all my pains on an attempt to produce something that should be agreeable to the good, profitable to the learned, and useful to letters.
The heart as the sun of the body:
The heart, consequently, is the beginning of life; the sun of the microcosm, even as the sun in his turn might well be designated the heart of the world; for it is the heart by whose virtue and pulse the blood is moved, perfected, and made nutrient, and is preserved from corruption and coagulation; it is the household divinity which, discharging its function, nourishes, cherishes, quickens the whole body, and is indeed the foundation of life, the source of all action.
And, finally, a warning on the implacability of ancient doctrine:
Doctrine once sown strikes deep its root, and respect for antiquity influences all men.
Read information about the authorWilliam Harvey (1 April 1578 – 3 June 1657) was an English physician. He was the first to describe completely and in detail the systemic circulation and properties of blood being pumped to the brain and body by the heart, though earlier writers had provided precursors of the theory. After his death the William Harvey Hospital was constructed in the town of Ashford, several miles from his birthplace of Folkestone.
At the time of Harvey's publication, Galen had been an influential medical authority for several centuries. Galen believed that blood passed between the ventricles by means of invisible pores. According to Galen's views, the venous system was quite separate from the arterial system, except when they came in contact through the unseen pores. Arabic scholar Ibn al-Nafis had disputed aspects of Galen's views, providing a model that seems to imply a form of pulmonary circulation in his Commentary on Anatomy in Avicenna's Canon (1242). Al-Nafis stated that blood moved from the heart to the lungs, where it mixed with air, and then back to the heart, from which it spread to the rest of the body. Harvey's discoveries inevitably and historically came into conflict with Galen's teachings and the publication of his treatise De Motu Cordis incited considerable controversy within the medical community. Some doctors affirmed they would "rather err with Galen than proclaim the truth with Harvey." Galen incompletely perceived the function of the heart, believing it a "productor of heat", while the function of its affluents, the arteries, was that of cooling the blood as the lungs "...fanned and cooled the heart itself". Galen thought that during dilation the arteries sucked in air, while during their contraction they discharged vapours through pores in the flesh and skin.
Independently from Ibn Al-Nafis, Michael Servetus identified pulmonary circulation, but this discovery did not reach the public because it was written down for the first time in the Manuscript of Paris in 1546. It was later published in the theological work which caused his execution in 1553, almost all copies of which were destroyed. Pulmonary circulation was described by Andreas Vesalius, before Harvey would provide a refined and complete description of the circulatory system.
Harvey's other major work was Exercitationes de generatione animalium, published in 1651.
The book starts with a description of development of the hen's egg. The major part is theoretical, dealing with Aristotle's theories and the work of the physicians following Galen and up to Fabricius. Finally he deals with embryogenesis in viviparous animals especially hinds and does. The treatment is generally Aristotelian and limited by use of a simple magnifying lens.
Needham claims the following achievements for this work.
His doctrine of omne vivum ex ovo (all life comes from the egg) was the first definite statement against the idea of spontaneous generation. He denied the possibility of generation from excrement and from mud, and pointed out that even worms have eggs.
He identified the citricula as the point in the yolk from which the embryo develops and the blastoderm surrounding the embryo.
He destroyed once and for all the Aristotelian (semen-blood) and Epicurean (semen-semen) theories of early embryogeny.
He settled the long controversy about which parts of the egg were nutritive and which was formative, by demonstrating the unreality of the distinction.
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