Harvey, William.  The Works of William Harvey.  London for the Sydenham Society: 1847.

Of the Method to be pursued in studying Generation

(from the Introduction to Essays on the Generation of Animals)

            Since in Animal Generation, (and, indeed, in all other subjects upon which information is desired,) inquiry must be begun from the causes, especially the material and efficient ones, it appears advisable to me to look back from the perfect animal, and to inquire by what process it has arisen and grown to maturity, to retrace our steps, as it were, from the goal to the starting place: so that we have attained to the principles; at the same time we shall perceive from what primary matter, and from what efficient principle, and in what way from these the plastic force proceeds; as also what processes nature brings into play in the work.  For primary and more remote matter, by abstraction and negation (being stripped of its garments as it were) becomes more conspicuous; and whatever is first formed or exists primarily in generation, is the material cause of everything that succeeds.  For example, before man attains to maturity, he was a boy, an infant, an embryo.  And then it is indispensable to inquire further as to what he was in his mother’s womb before he was an embryo or foetus; whether made up of three bubbles, or a shapeless mass, or a conception or coagulum proceeding from the mingled seminal fluids of his parents, or [163] what else, as we have it delivered to us by writers.  In like manner, before a fowl had attained to maturity or perfection,--because capable of engendering its like,--it was a chicken; previous to which it was an embryo or foetus in the egg; and before this, Hieronymus Fabricius, of Aquapendente, has observed rudiments of the head, eye, and spine.  But when he asserts that the bones are formed before the muscles, heart, liver, lungs, and precordial parts, and contend that all the internal organs must exist before the external one, he followed probabilities according to previous notions rather than inspection, and quitting the evidences of senses that rest on anatomy, he seeks refuge in reasonings upon mechanical principles; a procedure that is perfected; and this the rather as he expressly proposed to himself to write himself to write the history of the formation of the chick in the egg, and to exhibit in figures what happens in the course of each successive day.  It would have been in harmony with such a design, I say, had we been informed, on the testimony of the senses, of what parts are formed first, together, or subsequently in the egg; and not had mere opinions or musty conjectures, and the instances of houses and ships, adduced in illustration of the order and mode of formation of the parts. 

            We, therefore, in conformity with the method proposed, shall show in the first place in the egg, and then in the conceptions of other animals, what parts are first, and what are subsequently formed by the great God of Nature with inimitable providence and intelligence, and most admirable order.  Next we shall inquire into the primary matter out of which, and the efficient cause by which generation is accomplished, and also the order and economy of generation, as observed by us; that from thence, from its own work, we may have some certain information of the several faculties of the formative and vegetative [165] soul, and the nature of the soul itself, judging from its members or organs, and their functions.

            This, indeed, cannot be done in all animals: first, because a sufficient number of several of these cannot be commanded; and again, because, from the small size of many, they escape our powers of vision.  It must suffice, therefore, that is done in some kinds which are more familiarly known to us, and that we refer all the rest of these as types or standards.

            We have, therefore, selected those that may tend to render our experiments more undeniable, viz. the larger and more perfect animals, and that are easily within reach.  For in the larger animals all things are more conspicuous; in the more perfect, they are also more distinct; and in those that we can command, and that live with us, everything is more readily examined: we have it in our power so often as we please to repeat our observations, and so to free them from all uncertainty and doubt.  Now, among oviparous animal of this description, we have the common fowl, the goose, duck, pigeon; and then we have frogs, and serpents, and fishes; crustacean, testacea, and mollusca; among insects, bees, wasps, butterflies and silkworms; among viviparous creatures, we have sheep, goats, dogs, cats, deer, and oxen; lastly, we have the most perfect of all animals, man. 

            Having studied and made ourselves familiar with these, we may turn to consideration of 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; for all animals resemble one or other of those above mentioned, and agree with them either generally; for all animals resemble one or other of those above mentioned, and agree with them either generally or specifically, and are procreated in the same manner, or the mode of their generation at least is referrible by analogy to that of one or other of them.  For Nature, perfect and divine, is ever in the same things harmonious with herself, and as her works either agree or differ, (viz. in genus, species, or some other proportion,) [166] so is her agency in these (viz generation or development either same or diverse. He who enters on this new and untrodden path, and out of vast realm of Nature endeavors to find the truth by means of anatomical dissections and experiments, is met by such a multitude of facts, and these of so unusual an aspect, that he may find it more difficult to explain and describe to others the things he has seen, then he reckoned it labour to make his observations; so many things are encountered that require naming; such is the abundance of matter and the dearth of words. But if he would have recourse to metaphors, and by means of old and familiar terms would make known his ideas concerning the things he has newly discovered, the reader would have little chance of understanding him better than if they were riddles that were propounded; and of that thing itself, which he had never seen, he could have no conception.  But then, to have recourse to new unusual terms were less to bring a torch to lighten, than to darken things still more with a cloud: it were to attempt an explanation of a matter unknown by one still more unknown, and to impose a greater toil on the reader to understand meaning of words than to comprehend the things themselves.  And so it happens that Aristotle is believed by the inexperienced to be obscure in many places; and on this account, perhaps, Fabricius of Aquapendente rather intended to exhibit the chick in ovo in his figures that to explain it formation in words. 

            Wherefore, courteous reader, be not displeased with me, if, in illustrating the history of the egg, and in my account of the generation of the chick, I follow a new plan, and occasionally have recourse to unusual language.  Think me not eager for vainglorious fame rather than anxious to lay before you observations that are true, and that are derived immediately from the nature of things.  That you may not do me this injustice, I would have you know that I tread in the footsteps of those who have already thrown a light upon this subject, and that, wherever I can, I make use of their words [167].  And foremost of all among the ancients I follow Aristotle; among he moderns, Fabricius of Aquapendente; the former as my leader, the latter as me informant of the way.  For even as they who discover new lands, and first set foot on foreign shores, are wont to give them new names which mostly descend to posterity, so also do the discovers of things and the earliest writers with perfect propriety give names to their discoveries.  And now I seem to hear Galen admonishing us, that we should but agree about things, and not dispute greatly about the words.

EXERCISE THE TWENTY-NINTH

Of the manner, according to Aristotle, in which a perfect and

fruitful egg is produced by the male and female fowl

Shortly before we said that a fruitful egg is not engendered spontaneously, that it is not produced save by a hen, and by her only through the concurrence of the cock.  This agrees with the matter of the following sentence of Aristotle: “The principles of generation have particular reference to male and female; the male as supplying the original of motion and reproduction; the female as furnishing the matter.”

In our view, however, an egg is a true generative seed, analogous to the seed of a plant; the original conception arising between the two parents, and being the mixed fruit or product of both.  For as the egg is not formed without the hen, so is it not made fruitful without the concurrence of the cock. 

We have therefore to inquire how the egg is produced by the hen and is fertilized by the cock; for we have seen that hypenemic eggs, and these animated too, are engendered by the hen, but that they are not prolific without the intercourse of the cock.  The male and the female consequently, both set their mark [288] upon a fruitful egg; but not, I believe, in the way in which Aristotle imagines viz.: that the male concurs in the motion and commencement of generation only, the female supplying nothing but the matter, because the contrary of this is obvious in hypenemic eggs.  And although it be true as he says: “That male and female differ in respect to reason, because that faculty of each is different, and, in respect of sense, because certain parts differ likewise.  The difference according to reason boasts this distinction, that the male has power of engendering in another; the female has only the power of engendering in herself; whereby it comes that which is engendered is produced, this being contained in that which engenders.  But as males and females are distinguished by certain faculties and functions, and as an instrument is indispensable, to every office, and the parts of the body are adapted as instruments of the functions, it was necessary that certain parts should be set aside for purposes of procreation and coition, and these differing from one another, whereby the male differs from the female.”

            It does not, however, follow from thence, that what he appears inclined to infer is correct, where he says: “The male is the efficient agent, and by the motion of his generative virtue (geniture), creates what is intended from the matter contained in the female; for the female always supplies the matter, the male the power of creation, and this it is which constitutes one male, another female.  The body and the bulk, therefore, are necessarily supplied by the female; nothing of the kind is required from the male; for it is not even requisite that the instrument, nor the efficient agent itself, be present in the thing that is produced.  The body, then, proceeds from the female, the vital principle (anima) from the male; for the essence of every body is its vital principle (anima).”  But an egg, and the animated, is engendered by the pullet without the concurrence of the male; whence it appears that the hen too, or the female, may be the efficient agent, and that all creative force or vital power (anima) is not derived exclusively from the male. This view indeed appears to be supported by the instance quoted by Aristotle himself, for he says: “Those animals not of the same species, which copulate, (which those animals do [289] that correspond in their seasons of heat and times of uterogestation, and do not differ greatly in their size,) produce their first young like themselves, but partaking of the species of both parents; of this description is the progeny of the fox and dog, of the partridge and common fowl, &c.; but in the course of time from diversity results diversity, and the progeny of these different parents at length acquires the form of the female as the foreign seed is changed at last in conformity with the nature of the soil, which supplies matter and body to the seed. 

            From this it appears, that in the generation of the partridge with the common fowl it is not the male alone that is efficient, but the female also; inasmuch as it is not the male form only, but one common or subordinate that appears in the hybrid, as like the female as it is like the male in vital endowment (amina), and bodily form.  But the vital endowment (anima) is that which is the true form and species of an animal.

            Farther, the female seems even to have superior claim to be considered the efficient cause: “In the course of time,” says the philosopher, “the progeny of different species assumes the form of the female;” as if the semen or influence of the male were less powerful; as if the species impressed by him disappeared with the lapse of time, and were expelled by a more powerful efficient cause.  And the instance from the soil confirms this still farther: “for foreign seeds are changed at the length according to the nature of the soil.”  Whence it seems probable that the female is actually of more moment in generation than the male; for, “in the world at large it is admitted that the earth is to nature as the female or mother, whilst climate, the sun, and other things of the same description, are spoken of by the names of generator and father.”  The earth, too, spontaneously engenders many things without seed, and among animals, certain females, but females only, procreate of themselves and without the concurrence of the male: hens, for example, lay hypenemic eggs; but males; without the intervention of females, engender nothing.

            By the same argument, indeed, by which the male is maintained to be the principle and prime ‘efficient’ in generation, it would seem that the female might be confirmed in the prerogative [290] of έυέξγέίά or efficiency.  For is not that to be accounted efficient in which reason of the embryo and the form of the work appear; whose obvious resemblance is perceived in the embryo, and which, as first existing, calls forth the other?  Since, therefore, the form, cause, and similitude inhere in the female not less—and it might even be said that they inhere more—than in the male, and as she also exists previously as prime mover, let us conclude for certain that the female is equally efficient in the work of generation as the male. 

            And although Aristotle says well truly, “that the conception or egg receives no part of its body from the male, but only its form, species, and vital endowment (anima), and from the female its body solely, and its dimensions,” it is not yet made sufficiently to appear that the female, besides the matter, does not in some measure contribute form, species, and vital endowment (anima).  This indeed is obvious in the hen which engenders eggs without the concurrence of a male; in the same way as trees and herds, in which there is no distinction of sexes, produce their seeds.  For Aristotle himself admits, that even the hypenemic egg is endowed with a vital principle (anima).  The female must therefore be esteemed the efficient cause of the egg.

            Admitting that the hypenemic egg is possessed of a certain vital principle, still it is not prolific; so that it must further be confessed that the hen of herself is not the efficient cause of a perfect egg, but that she is made so in virtue of an authority, if I may use the word, or power required of the cock.  For the egg, unless prolific, can with no kind of propriety be accounted perfect, it only obtains perfection from the male, or rather from the female, as it were upon precept from the male; as it the hen received the art and reason, the form and laws of the future embryo from his address. 

And so in like manner the female fowl, like to a fruitful tree, is made fertile by coition; by this is she empowered not only to lay eggs, but these perfect and prolific eggs.  For although the hen have as yet no rudiments of eggs prepared in her ovary, nevertheless, made fertile by the intercourse of the male, she by and by not only produces [291] them there, but lays them teeming with life, and apt to produce embryos.  And here that practice of the poor folks find it application: “Having hens at home, but no cock, they commit their females to a neighbor’s male for a day or two; and from that short sojourn the fecundity of the whole eggs that will be laid during the current season is secured.”  Not only are those eggs which are still nothing more than yelk and have no albumen, or which exist only as most minute specks in the ovary, but eggs not yet extant, that will be conceived long afterwards, rendered fertile by the same property.

EXERCISE THE FORTY-EIGHTH

The opinion of Fabricius on the efficient cause of the chick is refuted.

            AS I have chosen Aristotle, the most eminent among the ancient philosophers, and Fabricius of Aquapendente, one of the foremost anatomist of modern times, as my especial guides and sources of information on the subject of animal generation, when I find that I can make nothing of Aristotle upon a particular topic, I straightway turn to Fabricius; and now I desire to know what he thought of the efficient cause of generation.

            I find that he endeavours to satisfy three doubts or difficulties involved in this subject: First, What is the ‘efficient’ of the chick?  This he answers, by saying, the semen of the male.  Secondly, how does this appear in the egg, and in what way does the semen of the cock fecundate the egg?  Thirdly and lastly, In what order are the parts of the chick engendered?

            As the first query, it appears from our observations, that the cock and his seminal fluid are verily the ‘efficient,’ but [351] not the ‘adequate’ cause of generation; that the hen comes in here as something.  In this place, therefore, we are principally to inquire how the semen of the cock fecundates the egg otherwise unprolific and secures the engenderment of a chick from it?

            But let us hear Fabricius: “Those things differ,” he observes, “that are produced from eggs from those that originate from semen, in this, that oviparous animals have the matter from which the embryo is incorporated distinct and separate from the agent; whilst viviparous animals have the efficient cause and the matter associate concorporate.  For in the fowl the semen of the cock, which neither is nor can be in the egg; the ‘matter,’ again is the chalazae from which the foetus is incorporated.  These two differ widely from one another; for the chalazae are added after the vitellus is formed, whilst it is passing through the second uterus, and are an accession to the internal egg; the semen galli, on the contrary, is stored near the fundament, is separated from the chalazae by a great interval, and nevertheless by its irradiating faculty, fecundates both the whole egg and the uterus.  Now in the viviparous animal, the semen is both ‘matter’ and ‘agent,’ the two consisting and being conjoined in the same body.”

            Our author appears to have introduced this distinction between oviparous and viviparous animals, that he might spare, or at all events, that he might not directly shock or upset the notions of medical writers on the generation of man, they teaching that the seminal fluids of either sex, projected together in intercourse, are mingled; that as one or other preponderates, this becomes the ‘efficient,’ that stands in lieu of the ‘matter;’ and that the two together, tending to the same end, amalgamate into the ‘conception’ of the viviparous animal.

            But when he finds that neither in the egg nor uterus of the fowl is there any semen or blood, and avow his belief that nothing is emitted by the male in intercourse, that can by possibility reach the uterus of the female, nor in the egg discovers a trace of aught supplied by the male, he is compelled [352] to doubt how the semen, which is nowhere to be detected, which is neither mixed with the ‘geniture’ of the female nor yet is added to it, nor touches it can fecundate the egg, or constitute the chick.  And this all that more urgently, when he has stated that a few connections in the beginning of the season suffice to secure the fecundity of all the eggs that will be laid in its course.  For how should it seem otherwise that impossible that from the semen galli communicated in the spring, but now long vanished, lost or consumed, the eggs that continue to be laid through the summer and autumn, should still be rendered fruitful and fit to produce pullets?

            It is that he may meet such a difficulty half way, that he coins the difference which has been noticed.  By way of bolstering up his views, he farther adduces three additional considerations:--First, since the semen galli is neither extant in the egg, nor was ever present in the uterus, not is added as ‘material cause’ as in viviparous animals, he has chosen to make it resident for a whole year in the body of the hen.  And then that he may have a fit receptacle or storehouse for the fecundating fluid, he find a blind sac near the inlet to the uterus, in which he says the cock deposits his semen, wherein as in a treasury, it is stored, and from which all the eggs are fecundated.  Lastly, although the semen in that bursa comes into contact neither with the uterus, nor the egg, nor the ovary, whereby it might fecundate the egg, or secure the generation of a chick, he says, nevertheless, that from thence, a certain spiritual substance or irradiation penetrates to the egg, fecundates it chalazae, and from these produces a chick.  By this affirmation, however, he appears to support the opinion of Aristotle, namely, that the female supplies the ‘matter’ in generation, the male the ‘efficient force;’ and to oppose the postulate of medical writers about the mixture of seminal fluids, for the sake of which, nevertheless, as I have said, he seems to have laid down his distinction between oviparous and viviparous animals.  To give enumerate the changes which the semen, not yet emitted, but laid up in the testes and vesiculae seminales of animals, occasions.

            But besides the fact that all this does not bear upon the [353] question, for the principal element under discussion is, not how the semen galli renders the egg prolific, but rather, how does the semen galli fashion and construct the chick from the egg?  Almost everything he adduces in support of his view appears either false or open to suspicion, as is obvious, from the facts stated in our history; for neither is the blind cavity situated at the root of the uropygium or coccyx of the fowl, which he entitles “bursa,” destined as a receptacle for the semen of the cock, nor can any semen be discovered there, as we have said; but the cavity is encountered in the male as well as in the female fowl.

            Our authority nowhere explains what he understands by a “spiritual substance,” and an irradiation:” nor what he means by “a substance through whose virtue the egg is vivified:” he does not say whether it is any “corporeal” or “formal” substance, by which “irradiation” proceeds from the semen laid up in the bursa, and, (what is especially required,) constructs a pullet from the egg.

            In my opinion, Fabricius does no more here than say: “It produces the chick because it irradiates the egg; and forms because it vivifies;” he attempts to explain or illustrate the exceedingly obscure subject of the formation of a living being by means still more obscure.  For the same doubt remains untouched, how, to wit, the semen of the cock without contact, and “external efficient” at best, separate in point of place, and existing in the bursa, can form the internal parts of the foetus in ovo,--the heart, liver, lungs, intestines, &c., out of the chalazae by “irradiation.”  Unless, indeed, our authors will have it that all takes place at the dictum as it were of a creator seated on his throne, and speaking the words: Let such things be! Namely, bones for support, muscles for motion, special organs for sense, members for action, viscera for concoction and the like, and all ordered for an end and purpose with foresight, and understanding and art.  But Fabricius nowhere demonstrates that the semen has any virtue, nowhere explains that manner in which without so much as contact the semen can effect such thing; particularly when we see that the egg incubated by a bird of another kind than that which laid it, or cherished in any other way, or in doing [354] or in an oven, far from the bursa of the parent hen, is still quickened and made to produce an embryo.

            The same difficulty still remains, I say: how or in what way is the semen of the cock the “efficient” of the chick?  It is in the no wise remover by invoking the irradiation of a spiritual substance.  For did we even admit that the semen was stored in the burse, and that it is incorporated the embryo from the chalazae by metamorphosis and irradiation, we should not be the less deeply immersed in the difficulty of accounting for the formation of all the internal parts of the chick.

            Wherefore, in investigating the efficient cause of the chick, we must look for it as inhering in the egg, not as concealed in the bursa; and it must be such, that although the egg have long been laid, be miles removed from the hen that produced it, and be set under another hen that its parent or even under a bird of a different kind, such as a turkey or guineafowl, or merely among hot sand or dung, or in an oven constructed for the purpose, as is done in Egypt, it will still cause the egg to produce a creature of the same species as its parents like them both male and female, and it the parents were of different kinds, of a hybrid species, and having a mixed resemblance.

            The knot therefore remains untied, neither Aristotle nor Fabricius having succeeded even in loosening it, namely: how the semen of the male or of the cock forms a pullet from an egg, or is to be termed the “efficient” of the chick, especially when it is neither present in, nor in contact with, nor added to the semen are the efficient cause of the chick, still admitted, that no one has yet sufficiently explained how it is so particularly in our common hen’s egg.

EXERCISE THE SIXTY-THIRD

Of the generation of viviparous animals

            Thus far we have treated mainly of the generation of oviparous animals, we have still speak particularly of the other species of generation, the viviparous, to wit, in which many things identical with those we have noticed in oviparous generation will come to be observed.  These we have reduced in order, and here at length present for consideration.  Even the parts that appear paradoxical and in contradiction with the current views of generation will, I believe, be found entirely in conformity with truth. 

Among viviparous animals, man the most perfect of all creatures, occupies the foremost place; after him come our ordinary domestic animals, of which some are soliped, such as the horse and ass; others bisulcate, as the ox, goat, sheep, deer, and hog; others digate, such as the dog, cat, rabbit, mouse, and others of the same description; from the modes of whose [462] generation a judgment may be formed of that of all other viviparous animals.  Wherefore I shall propose a single genus by way of general example or type, as we did in the case of the oviparous class; this made familiar to us, will serve as a light or standard, by means of which all the others may be judged of by analogy.

The reasons that led me to select the hen’s egg as the measure of the eggs in general have been already given; eggs are of little price, and are everywhere to be obtained, conditions that permit repeated study, and enable us cheaply and readily to test the truth of statements made by others.

We have not the same faculties in studying the generation of viviparous animals: we have rarely, if ever, an opportunity of dissecting the human uterus; and then to enter on the subject experimentally in the horse, ox, sheep, goat, and other cattle; dogs, cats, rabbits, and the like, however, will supply those with subjects who are desirous of putting to the test of experiments the matters that are in to be delivered by us in this place.

            In the uterus of all animals there is consequently present a prime conception of primoridium, which, on Aristitle’s testimony, “is like an egg surrounded with a membrane from which the shell had been removed.”  This fact will appear still more plainly from what is about to be said.  Meantime let us conclude with the philosopher, “that all living creatures, whether they swim, or walk, or fly, and whether they come into the world with the form of an animal or of an egg, are engendered in the same manner.”

EXERCISE THE SIXTY-FOURTH

The generation of viviparous animals in general is illustrated from the

 history of that of the hind and doe, and the reason of this selection

            It was customary with his Serene Majesty, King Charles, after he had come to man’s estate, to take the diversion of hunting almost every week, both for the sake of finding relaxation from graver cares, and for his health; the chase was principally the buck and does, and no prince in the world had greater herds of deer, either wandering in freedom through the wilds and forests, or kept in parks and chases for this purpose.  The game during the three summer months was the buck, then fat and in season; and in the autumn and winter, for the same length of time, the doe.  This gave me an opportunity of dissecting numbers of these animals almost every day during the whole of the season when they were rutting, taking the male, and falling the young; I had occasion, so often as I desired it, to examine and study all the parts, particularly those dedicated to the offices of generation.

            I shall therefore consider the generation of viviparous animals in general, from the particular history of the hind and the does, as the instance most convenient to me; and as I have done above, in speaking of oviparous generation, where I have referred everything to the common fowl, so shall I here in discussing viviparous generation, refer all the fallow deer and roe.  [467] In taking this course, I am not moved by the same reasons as I was in reference to the hen’s egg; but because the great prince, whose physician I was in, besides taking much pleasure in such inquires, and not disdaining to bear witness to me discoveries, was pleased in his kindness and munificence to order me an abundant supply of these animal and repeated opportunities of examining their bodies.

SYNOPSIS

            William Harvey was a distinguished physician of the seventeenth century.  Harvey was educated by some of the great scientists of his time and was highly knowledgeable of the scientist theories preceding his time.   Harvey was greatly intrigued by the views of the ancient Aristotle and developed a number of his own ideas based on Aristotle’s theories.  It was from Aristotle’s theory of the primacy of blood that allowed Harvey to make breakthroughs about circulation and generation of animals.  His advancements greatly enhanced the study of anatomy.  Harvey also revolutionized the means by which science was performed through the use of innovative, investigational techniques.  William Harvey became a well-known name in science because he made profound accomplishments that changed the way scientists performed and the way people viewed the human body.

    William Harvey was born on April 1, 1578, in Folkestone, England. At the age of sixteen, Harvey enrolled in Gonville and Caius College in Cambridge where he obtained a bachelor's degree in 1597.  He went on to study medicine under Hieronymus Fabricius at the University of Padua in Italy.  Fabricius was involved in the study of blood flow in the body, which motivated Harvey to research this branch as well.  After moving to England, William Harvey was appointed as a personal physician to King Charles (Britannica).  Within his study of blood, Harvey was able to form the theory of the circulation of blood through the body, which he published in ‘On the Motion of the Heart and Blood in Animals', in 1628.  The book brought Harvey fame and made him a respected name in science.  During his experiments, William Harvey became skeptical of preformation, which sprouted an interest in animal generation.  He decided to perform a study on reproduction that resulted in his discovery that some parts are engendered before others.  This disproved the common view of preformation (Pagel 33).  He published his final writings in the “Essays on the Generation of Animals.”  After a productive and eventful life, William Harvey died in London on June 3, 1657.

            Through his investigation founded on beliefs of Aristotle, William Harvey was able to hypothesize on the movement of blood in the body.  Prior to William Harvey’s research , the medical view of blood in the body came from a Greek doctor by the name of Galen.  Galen explained the flow of blood as a to-and-fro movement being pumped by the veins and arteries themselves.  Galen also believed that blood was made and then used up in the body.  His conclusions were drawn mainly from outer appearances (Bayon 444).  This made Harvey’s work more accurate because he performed specific experiments and calculations.  One reason Harvey was able to determine the movement of blood through the body was founded in Aristotle’s belief of the perfection of circular motion because it is continuous path (Pagel 28).  William Harvey combined this idea with Arsitotle’s view of the power of the heart to act independently of the brain.  From these notions, Harvey created the theory of a constant circulation of blood throughout the body by the pumping of the heart.  He began researching his hypothesis with a hen’s egg.  He discovered that the first drops of blood in the hen’s egg eventually gave movement to the heart and to the rest of the blood.  If blood provided to movement to the body, it must be able to reach all parts of the body.  Then he carefully computed the amount of blood being released from the heart which eventually traveled to the various parts of the organism.  Harvey created experiments which proved that the amount of blood leaving the heart could not possibly be absorbed by the body as new blood was being created.  He was the first to show that the volume of blood pumped surpassed the amount in the body.  Consequently, Harvey surmised, Galen was incorrect in thinking new blood it formed, and instead, the blood must move in a circuit to account for the massive quantities of blood being pumped (Lubitz 276).    

            Harvey possessed a lifelong obsession with animal generation.  He explained his fascination with the perfection of animals which brought about his desire to find out how the organisms arise in his introduction to his Essays on the Generation of Animals (Harvey 167).  His fascination sprouted from his study of Aristotle’s ideas of generation.  Harvey decided to further investigate Aristotle’s views by studying a hen’s eggs in order to grasp the means of generation in animals.   He justified his decision and his plan of pursuing his research in “Of the Method to be pursued in studying Generation” passage of the introduction to Essays of the Generation of Animals.  First of all, a hen’s egg had a simple structure and readily available for frequent experimentation.  In the introduction to his essays, he further explained that his choice of using a chick egg was acceptable because all animals had similar means of generation.  Results drawn from scrutiny of a hen’s egg could be related to the reproduction in more complex animals, even animals that did not produce an egg.  All animals reproduce with some form of an egg, which he considered to be a metaphor for the simple origin of any new life form (Harvey 164). Harvey deemed it necessary to start with the less complicated animals because this would allow him to repeat the tests a number of times to once again ensure accurate results.  William Harvey’s strategy was to observe of the formation of a chick to create a history of its development.  Harvey would then use this information to show the cause of generation and the order in which it proceeded in (Harvey 163). 

Before Harvey’s research, scientists believed in a theory known as preformation, which assumed an animal already possessed the traits of the mature mammal and solely grrew in size in the mother’s womb.  William Harvey refuted these prior theories in his consideration of the history of an egg’s development.  He noticed that the fetus began as a single drop of blood and then further differentiated into an egg which later became the chick.  Consequently, he rejected the idea that an exact replica of the organism could be found in reproductive material of either the male or the female.  Harvey, however, learned by investigating the stages of development in the eggs that some parts of the animal are engendered before others. (Pagel 33). 

            Another concern of Harvey’s was the theories of previous scientists on the role of the male and the female in animal generation.  Former scientists attempted to find an answer to this mystery.  Galen assumed the yolk in a hen’s egg was a joint of male and female secretions (Gasking 21).  Aristotle hypothesized that the cause of generation was the male’s semen acting on the menstrual blood of the female making the menstrual blood the source of matter and the semen the efficient source (White 253).  Fabricius presumed the male caused the material and the female provided the nourishment.  Harvey wanted to solve the mystery of the purpose of each sex, so he examined the male and female genital systems of the deer of King Charles in the Royal Parks (Gasking 22).  Through Harvey’s investigation, he disproved Aristotle’s theories and clarified this in the passage “Of the manner, according to Aristotle, in which a perfect and fruitful egg is produced by the male and female fowl” in his essays (Harvey 288).  He did not consider Aristotle’s ‘efficient cause’ as relevant in the discussion of reproduction because Aristotle’s agent of the efficiency was semen.  In Harvey’s mind, semen is an external cause and could not produce an effect on the soul of the offspring because it was not with it throughout its lifetime (Gasking 34).  Also, Harvey explained the female must have a role in the efficiency when he stated, “The earth, too, spontaneously engenders many things without seed, and among animals, certain females, but females only, procreate of themselves and without the concurrence of the male: hens, for example, lay hypenemic eggs; but males; without the intervention of females, engender nothing” (Harvey 289).  He deduced that if the female can procreate without the male, then the male must not be the only agent to produce the efficiency.  He was able to develop this view by looking at less complex organisms and extending it to more evolved animals because he considered all animals to share similar reproductive processes.  Accordingly, he allowed himself to make broad generalizations about generation through species barriers. 

            Although he was taught by Fabricius, William Harvey criticized some of his teacher’s views about reproduction.  In fact, the inaccuracy he saw in Fabricius’s beliefs prompted his investigation of animal generation (Pinto-Correia 109).  The flaws Harvey detected were in Fabricius’s idea of the role semen played in reproduction.  His teacher thought that after the male had been in contact with the female, all the eggs are made fertile.  Upon his experimentation, Harvey found that the hen laid an egg ten days after interaction with the male, and then another thirteen days after.  He was able to conclude that the male did fertilize more than one of the yolks.

One of the many reasons for William Harvey’s success was his meticulous experimentation.  Scientists preceding William Harvey used experimentation in order to investigate; however, Harvey set a new standard for testing.  He made precise calculations before and during experiments.  For example, in his study of circulation, he calculated the exact amount of blood released from the heart with every thrust (Lubitz 3).  In Harvey’s experiments, he closely examined and dissected various animals.  While many scientists such as Galen used only careless observation, Harvey tested physically and then retested numerous times to ensure his results lacked error.  In fact, William Harvey was the first to apply quantitative and observational methods simultaneously within his research.  He picked test subjects that would be readily available for several experiments.  In the examination of blood and animal generation, Harvey used hen’s eggs because they were inexpensive and abundant.  As the King’s physician, Harvey examined deer in his studies of animal generation.  King Charles was fascinated by Harvey’s research, so he gave the carcasses of his weekly deer hunting to Harvey to dissect (Short 705).  The substitution of the mammal into testing greatly advanced Harvey’s research because he could relate his concepts of reproduction to an organism that did not produce an actual egg. 

The impact of William Harvey’s work was seen through the work of many other scientists.  For example, Descartes was intrigued by Harvey’s ideas of natural events having a specific process that were consistent in various organisms (Bayon 451).  Harvey’s theories could be seen laced into the writing of Descartes and in some of the conclusions he made on arterial blood.  William Harvey influenced medical developments as well.  William Harvey influenced Marcello Malpighi, and anatomy professor to investigate circulation.  He supplied missing links in the theories of Harvey, such as the discovery of the capillaries which provided the connection between the arteries and the veins (Wilson 166).  Other systems of the body were looked at differently after Harvey’s research of the circulation of blood.  He was able to distinguish between the pumping of the lungs from the movement in the lungs.  Although he was unable to solve the mystery of the movement of the lungs, Harvey’s questioning of the matter left the problem to his contemporaries to solve (Wilson 162).  Overall, Harvey’s ideas laid the foundation for a new way of looking at the human body.  The body could be seen as a combination of various systems working together, which became the modern day view of the human body.

BIBLIOGRAPHY

Harvey, William.  The Works of William Harvey.  Trans. Robert Willis, MD.  London: The Syenham Society, 1847.

"Harvey, William." Britannica Student Encyclopedia. 2004.  Encyclopædia Britannica Online School Edition.

30 Nov. 2004 <http://school.eb.com/ebi/article?tocId=9274787>.

Gasking, Elizabeth.  Investigations into Generation.  Baltimore: The John Hopkins Press, 1967.

Lubitz, Steven.  “Early Reactions to Harvey's Circulation Theory: The Impact on Medicine.”  Mount Sinai Journal of Medicine 71 Issue 4 (2004): 274.

Pagel, Walter.  “William Harvey and the Purpose of Circulation.” Iris 42 I (1951): 478-87.

Pinto-Correia, Clara.  The Ovary of Eve: Egg and Sperm and Preformation.  Chicago: The University of Chicago Press, 1997.

 Short, R.V.  “Where Do Babies Come From?”  Nature 403 Issue 6771 (2000): 705.

White, John.  “William Harvey and the Primacy of Blood.”  Annuals of Science  43 III (1986): 273-255.

Wilson, Leonard. “The Transformation of Ancient Concepts of Respiration in the Seventeenth Century.”  Iris 52 II (1960): 161-172.

Image taken from: <http://www.williamharvey.org/wm_harvey.htm>

By Michelle Houston (2004)