Medical Investigation
in Seventeenth Century
England
Charles W. Bodemer
Lester S. King
William Andrews Clark Memorial Library
Medical Investigation
in Seventeenth Century
England
Embryological Thought in
Seventeenth Century England
_by Charles W. Bodemer_
Robert Boyle as an Amateur Physician
_by Lester S. King_
Papers Read at a Clark Library Seminar,
October 14, 1967
William Andrews Clark Memorial Library
_University of California, Los Angeles/1968_
_Foreword_
Although the collection of scientific literature in the Clark Library
has already served as the background for a number of seminars, in the
most recent of them the literature of embryology and the medical aspects
of Robert Boyle's thought were subjected to a first and expert
examination. Charles W. Bodemer, of the Division of Biomedical History,
School of Medicine, University of Washington, evaluated the
embryological ideas of that remarkable group of inquiring Englishmen,
Sir Kenelm Digby, Nathaniel Highmore, William Harvey, and Sir Thomas
Browne. Lester S. King, Senior Editor of the _Journal of the American
Medical Association_, dealt with the medical side of Robert Boyle's
writings, the collection of which constitutes one of the chief glories
of the Clark Library. It was a happy marriage of subject matter and
library's wealth, the former a noteworthy oral presentation, the latter
a spectacular exhibit. As usual, and of necessity, the audience was
restricted in size, far smaller in numbers than all those who are now
able to enjoy the presentations in their present, printed form.
C. D. O'MALLEY
_Professor of Medical History, UCLA_
I
_Embryological Thought in Seventeenth
Century England_
CHARLES W. BODEMER
To discuss embryological thought in seventeenth-century England is to
discuss the main currents in embryological thought at a time when those
currents were both numerous and shifting. Like every other period, the
seventeenth century was one of transition. It was an era of explosive
growth in scientific ideas and techniques, suffused with a creative urge
engendered by new philosophical insights and the excitement of
discovery. During the seventeenth century, the ideas relating to the
generation and development of organisms were quite diverse, and there
were seldom criteria other than enthusiasm or philosophical predilection
to distinguish the fanciful from the feasible. Applying a well-known
phrase from another time to seventeenth-century embryological theory,
"It was the best of times, it was the worst of times, it was the age of
wisdom, it was the age of foolishness."[1]
Embryology underwent some very significant changes during the
seventeenth century. At the beginning of the century, embryology was
descriptive and clearly directed toward morphological goals; by the end
of the century, a dynamic, more physiological attitude was apparent, and
theories of development derived from an entirely different philosophic
base. During this time, English investigators contributed much, some of
ephemeral, some of lasting importance to the development of embryology.
For this discussion, we will divide the seventeenth century into three
overlapping, but generally distinct, periods; and, without pretence of
presenting an exhaustive exposition, we will concentrate upon the
concepts and directions of change characteristic of each period, with
primary reference to those individuals who best reveal the character of
seventeenth-century English embryology.
An understanding of the characteristics of embryological thought at the
beginning of the seventeenth century may enhance appreciation of later
developments. During the latter part of the sixteenth century, the study
of embryology was, for obvious reasons, most often considered within the
province of anatomy and obstetrics. From Bergengario da Capri to Jean
Riolan the Younger, study of the fetus was recommended as an adjunct of
these subjects, and it required investigation by direct observation, as
decreed by the "restorers" of anatomy. Embryonic development was,
however, also studied independently of other disciplines by a smaller
group of individuals, and the study of chick development by Aldrovandus,
Coiter, and Fabricius ab Aquapendente laid the basic groundwork of
descriptive embryology. In either case, during the last half of the
sixteenth century the attempt of the embryologist to break with the
traditions of the past was overt, although consistently unsuccessful.
When dealing with the fetus, the investigators of this period were,
almost to a man, Galenists influenced to varying degrees by Hippocrates,
Aristotle, and Avicenna. Each felt compelled to challenge the immediate
authority, and yet their intellectual isolation from the past was
incomplete, and their views on embryogeny corresponded with more often
than they differed from those of the person they railed against.
Embryology emerged as a distinct scientific discipline during the last
half of the sixteenth century and early years of the seventeenth century
as a result of the aforementioned investigations of Aldrovandus, Coiter,
and Fabricius. Concerned with description and depiction of the anatomy
of the embryo, they established a period of macro-iconography in
embryology. The macro-iconographic era was empirical and based upon
first-hand observation; it was concerned more with the facts than with
the theories of development. This empiricism existed in competition with
a declining, richly vitalistic Aristotelian rationalism which had
virtually eliminated empiricism during the scholastic period. However,
the decline of this vitalistic rationalism coincided with the rise of a
mechanistic rationalism which had its roots in ancient Greek atomistic
theories of matter. The empiricism comprising the _leitmotif_ of the
macro-iconographic movement then became blended with, or, more often,
submerged within, the new variety of rationalism; hence, mechanistic
rationalism, divorced entirely or virtually from empiricism,
characterizes embryology during the first half of the seventeenth
century. It is a particularly vigorous strain of seventeenth-century
English embryological thought, well illustrated in the writings of that
English man of affairs, Sir Kenelm Digby.
Digby, whose name, according to one biographer, "is almost synonymous
with genius and eccentricity,"[2] could claim our attention not only as
a scientist of talent, but also as a statesman, soldier, pirate, lover,
and a Roman Catholic possessed of sufficient piety and naked courage to
attempt the conversion of Oliver Cromwell. Like his father, who was
hanged for participation in the Gunpowder Plot, Digby was a political
creature, and during the Civil War he was imprisoned for several years.
When freed, Digby left England to settle in France. Spending much time
at the court of the Queen Dowager, who had been instrumental in securing
his release, and exposed to the vigorous intellectual currents of Paris
and Montpellier, Digby labored upon a treatise of greater scientific
substance and merit than his more famous work on "the powder of
sympathy." Published in 1644 under the title _Two Treatises, in the One
of Which, The Nature of Bodies; in the Other, the Nature of Mans Soule;
is Looked_ _into, in Way of Discovery of the Immortality of Reasonable
Soules_, the book consists of a highly individual survey of the entire
realms of metaphysics, physics, and biology.
Digby's cannons were aimed at scholasticism, which, despite "greatly
exaggerated" reports, did not die with the Middle Ages. The spirit of
scholasticism was alive in many quarters well into the seventeenth
century, and although many scholars worked in pursuit of original
knowledge, they did not always disturb the scholastic philosophic basis
from which their work derived. For example, in his impressive _De
formato foetu_, published in 1604, when Sir Kenelm Digby was one year
old, Fabricius all too often submerges a substantial body of
observations within a dense tangle of philosophical discussion. Thus, in
the same treatise that contains the first illustrations and commendably
accurate descriptions of the daily progress of the chick's development,
Fabricius devotes an inordinate amount of space to tedious discussions
of material and efficient causes in development, emphasizing thereby the
supremacy of the logical framework to the observations. In 1620, Digby's
last year of study at Oxford University, Fienus published a work, _De
Formatrice Foetus_, designed to demonstrate that the human embryo
receives the rational soul on the third day after conception and to
discuss at length such subjects as the efficient cause of embryogeny and
the proposition that the conformation of the fetus is a vital, not a
natural, action. Various expressions of Aristotelian and scholastic
biology were clearly abroad during the first half of the seventeenth
century, and there is reason, then, for Digby's attack upon Aristotelian
ideas of form and matter and of the persistence of "qualities" in
physics and "faculties" in biology.
Expressing his disdain of word-spinning, Digby attempts to explain all
phenomena by two "virtues" only, rarity and density working by local
motion. In discussing embryonic development, Digby writes, "...our
maine question shall be, Whether they be framed entirely at once; or
successively, one part after another? And, if this later way, which
part first?"[3] Toward this end, Digby makes some direct observations
upon the development of the chick embryo, incubating the eggs so that
the "creatures ... might be continually in our power to observe in them
the course of nature every day and houre."[4] His description of chick
development is of epigenetic bent:
...you may lay severall egges to hatch; and by breaking them at
severall ages you may distinctly observe every hourely mutation in
them, if you please. The first will bee, that on one side you shall
find a great resplendent clearnesse in the white. After a while, a
little spott of red matter like bload, will appeare in the middest
of that clearnesse fastened to the yolke: which will have a motion
of opening and shutting; so as sometimes you will see it, and
straight againe it will vanish from your sight; and indeede att the
first it is so litle, that you can not see it, but by the motion of
it; for att every pulse, as it openeth, you may see it, and
immediately againe, it shutteth in such sort, as it is not to be
discerned. From this red specke, after a while there will streame
out, a number of litle (almost imperceptible) red veines. Att the
end of some of which, in time there will be gathered together, a
knotte of matter which by litle and litle, will take the forme of a
head; and you will ere long beginne to discerne eyes and a beake in
it. All this while the first red spott of blood, groweth bigger and
solider; till att the length, it becometh a fleshy substance; and
by its figure, may easily be discerned to be the hart: which as yet
hath no other enclosure but the substance of the egge. But by litle
and litle the rest of the body of an animal is framed out of those
red veines which streame out all aboute from the hart. And in
processe of time, that body incloseth the hart within it by the
chest, which groweth over on both sides, and in the end meeteth,
and closeth it selfe fast together. After which this litle creature
soone filleth the shell, by converting into severall partes of it
selfe all the substance of the egge. And then growing weary of so
straight an habitation, it breaketh prison, and cometh out, a
perfectly formed chicken.[5]
Despite this observational effort, Digby's experience with the embryo is
quite limited, and his theory of development relates more to his
philosophical stance than to the facts of development. Indeed, the
theory he propounds is not necessarily consistent. On the one hand, it
posits a strictly mechanistic epigenesis, and on the other hand, it
incorporates the notion of "specificall vertues drawne by the bloud in
its iterated courses, by its circular motion, through all the severall
partes of the parents body."[6] Digby rejects an internal agent,
entelechy, or the Aristotelian formal and efficient causes. Similarly,
he disposes of the idea that the embryonic parts derive from some part
of each part of the parent's body or an assemblage of parts. This
possibility is eliminated, he contends, by the occurrence of spontaneous
generation. If a collection of parts was necessary, he asks, "how could
vermine breed out of living bodies, or out of corruption?... How could
froggs be ingendered in the ayre?"[7] Generation in plants and animals
must, then, according to Digby, proceed from the action of an external
agent, effecting the proper mingling of the rare and dense bodies with
one another, upon a homogeneous substance and converting it into an
increasingly heterogeneous substance. "Generation," he says,
is not made by aggregation of like partes to presupposed like ones:
nor by a specificall worker within; but by the compounding of a
seminary matter, with the juice which accreweth to it from without,
and with the streames of circumstant bodies; which by an ordinary
course of nature, are regularly imbibed in it by degrees; and which
att every degree do change it into a different thing.[8]
Digby argues that the animal is made of the juices that later nourish
it, that the embryo is generated from superfluous nourishment coming
from all parts of the parent body and containing "after some sort, the
perfection of the whole living creature."[9] Then, through digestion and
other degrees of heat and moisture, the superfluous nourishment becomes
an homogeneous body, which is then changed by successive transformations
into an animal.
Digby is frankly deterministic in his description of embryonic
development:
Take a beane, or any other seede, and putt it into the earth, and
lett water fall upon it; can it then choose but that the beane must
swell? The beane swelling, can it choose but breake the skinne? The
skinne broken can it choose (by reason of the heate that is in it)
but push out more matter, and do that action which we may call
germinating.... Now if all this orderly succession of mutations be
necessarily made in a beane, by force of sundry circumstances and
externall accidents; why may it not be conceived that the like is
also done in sensible creatures; but in a more perfect manner....
Surely the progresse we have sett downe is much more reasonable,
then to conceive that in the meale of the beane, are contained in
litle, severall similar substances.... Or, that in the seede of the
male, there is already in act, the substance of flesh, of bone, of
sinewes, of veines, and the rest of those severall similar partes
which are found in the body of an animall; and that they are but
extended to their due magnitude, by the humidity drawne from the
mother, without receiving any substantiall mutation from what they
were originally in the seede. Lett us then confidently conclude,
that all generation is made of a fitting, but remote, homogeneall
compounded substance: upon which, outward Agents working in the due
course of nature, do change it into an other substance, quite
different from the first, and do make it lesse homogeneall then the
first was. And other circumstances and agents, do change this
second into a thirde; that thirde, into a fourth; and so onwardes,
by successive mutations (that still make every new thing become
lesse homogeneall, then the former was, according to the nature of
heate, mingling more and more different bodies together) untill
that substance be produced, which we consider in the periode of all
these mutations....[10]
Digby thus makes a good statement of epigenetic development. He
attempts, without success, a physiochemical explanation of the
mechanisms of development, finally admitting:
I persuade my selfe it appeareth evident enough, that to effect
this worke of generation, there needeth not be supposed a forming
vertue ... of an unknowne power and operation.... Yet, in
discourse, for conveniency and shortnesse of expression we shall
not quite banish that terme from all commerce with us; so that what
we meane by it, be rightly understood; which is, the complexe,
assemblement, or chayne of all the causes, that concurre to produce
this effect; as they are sett on foote, to this end by the great
Architect and Moderatour of them, God Almighty, whose instrument
Nature is.[11]
Digby's general theory thus represents a strange mixture of epigenesis
and pangenesis, and is not entirely devoid of "virtues." It is, however,
a bold attempt to explain embryonic development in terms commensurate
with his time, and it embodies the same optimistic belief that the
mechanism of embryogenesis lay accessible to man's reason and logical
faculties that similarly led Descartes and Gassendi to comprehensive
interpretations of embryonic development comprising a maximum of logic
and minimum of observations.
The traditionalist reaction to the attack upon treasured and
intellectually comfortable interpretations of development was not slow
to set in. A year after the appearance of Digby's _Nature of Bodies_,
Alexander Ross published a treatise with a title indicating its goals
and content: _The Philosophicall Touch-Stone; or Observations upon Sir
Kenelm Digbie's Discourses of the nature of Bodies, and of the
reasonable Soule: In which his erroneous Paradoxes are refuted, the
Truth, and Aristotelian Philosophy vindicated, the immortality of mans
Soule briefly, but sufficiently proved_.[12] Ross supports the Galenist
tradition that the liver, not, as Digby claimed, the heart, forms first
in development. It can be no other way, he says, since the blood is the
source of nourishment and the liver is necessary for formation of the
blood. Furthermore, he contends, "the seed is no part of the ... aliment
of the body ... the seed is the quintessence of the blood."[13] Ross is
an epigeneticist, to be sure, but so was Aristotle, and Ross prefers to
maintain the supremacy of logic and the concepts of the Aristotelian
tradition as a guide to the interpretation of development.
In 1651, Nathaniel Highmore, a physician at Sherborne in Dorset,
published _The History of Generation_, which, he informs us, is an
answer to the opinions expressed by Digby in _The Nature of Bodies_.
Highmore's book is an important one in the history of embryology, since
it is the first treatment of embryogeny from the atomistic viewpoint and
because it contains the first published observations based upon
microscopic examination of the chick blastoderm. Admittedly, the
drawings illustrating Highmore's observations upon generation are, to
use a word often applied to modern art, "interesting," but they do
derive from actual observations of developing plant and animal embryos.
His observations on the developing chick embryo are quite full,
complete, and exact, and he also records some interesting facts
regarding development of plant seeds.
Highmore's theory of development appears to have emerged directly out of
his observations of development. In this sense, his theory rests upon a
more solid base than does the developmental theory of Digby. His theory
is a mixture of vitalism and atomism, designed to eliminate the "fortune
and chance"[14] resident in Digby's concept. "Generation," he says,
...is performed by parts selected from the generators, retaining
in them the substance, forms, properties, and operations of the
parts of the generators, from whence they were extracted: and this
Quintessence or Magistery is called the seed. By which the
Individuals of every Species are multiplied...
From this, All Creatures take their beginning; some laying up the like
matter, for further procreation of the same Species.
In others, some diffus'd Atomes of this extract, shrinking themselves
into some retired parts of the Matter; become as it were lost, in a
wilderness of other confused seeds; and there sleep, till by a
discerning corruption they are set at liberty, to execute their own
functions. Hence it is, that so many swarms of living Creatures are from
the corruption of others brought forth: From our own flesh, from other
Animals, from Wood, nay, from everything putrified, these imprisoned
seminal principles are muster'd forth, and oftentimes having obtained
their freedom, by a kinde of revenge feed on their prison; and devour
that which preserv'd them from being scatter'd.[15] Accounting thus for
sexual and spontaneous generation, Highmore defines two types of seminal
atoms in the seed--"Material Atomes, animated and directed by a
spiritual form, proper to that species whose the seed is; and given to
such matter at the creation to distinguish it from other matters, and to
make it such a Creature as it is."[16] The seminal atoms come from all
parts of the body, the spiritual atoms from the male, and the material
atoms from the female. The atoms of Democritus are thus transmuted into
the "substantial forms" and endowed either with the efficient cause of
Aristotle or, permitted to remain material, with Aristotle's material
cause. According to Highmore, the atoms are circulated in the blood,
which is a "tincture extracted from those things we eat," and these
various atoms retain their formal identity despite corruption. The
testicles abstract some spiritual atoms belonging to each part and, "As
the parts belonging to every particle of the Eye, the Ear, the Heart,
the Liver, etc. which should in nutrition, have been added ... to every
one of these parts, are compendiously, and exactly extracted from the
blood, passing through the body of the Testicles." Being here "cohobated
and reposited in a tenacious matter," the particles finally pass out of
the testes.[17] A similar extraction of the female seed occurs in the
ovaries. The female seed
...containing the same particles, but cruder and lesse digested,
from a cruder matter, by lesse perfect Organs, is left more
terrene, furnished with more material parts; which being united in
the womb, with the spiritual particles of the masculine seed;
everyone being rightly, according to his proper place, disposed and
ordered with the other; fixes and conjoynes those spiritual Atomes,
that they still afterwards remain in that posture they are placed
in.[18]
The theories of development promulgated by Digby and Highmore reveal the
chief formulations of mechanistic rationalism, more or less free of
empiricism, that were emerging as the vitalism of the sixteenth and
seventeenth centuries waned. There was little new in these theories:
both Digby's and Highmore's theories included different combinations of
elements of ancient lineage. Digby's concept was essentially free of
vitalistic coloring; akin to the embryological efforts of Descartes in
its virtual independence from observations of the developing embryo, it
was similarly vulnerable to Voltaire's criticism of Descartes, that he
sought to interpret, rather than study, Nature. This criticism is not so
applicable to Highmore, whose theory of development is more vitalistic
than Digby's, and is more akin to the concepts developed by Gassendi
than those of Descartes. Highmore had experience with the embryo itself,
and his actual contribution as an observer of development, although
hardly epochal, is worthy of note. But despite this empirical base,
Highmore has final recourse to a hypothesis blending many ancient ideas
and substituting the Aristotelian material and efficient causes for the
"fortune and chance" he objected to in Digby's hypothesis. It was _not_
easy in the seventeenth century to avoid falling back upon some variety
of cause or force.
In 1651, about two months before publication of Highmore's _History of
Generation_, a work appeared which marks another period in
seventeenth-century English embryology. William Harvey, _De Motu Cordis_
almost a quarter of a century behind him, now published _De Generatione
Animalium_, the work he said was calculated "to throw still greater
light upon natural philosophy."[19] This book is, perhaps, not as well
known as Harvey's treatise demonstrating circulation of the blood, but
it is an important work in the history of embryology and it occupies a
prominent position in the body of English embryological literature.
In _De Generatione_, Harvey provides a thorough and quite accurate
account of the development of the chick embryo, which, in particular,
clarified that the chalazae, those twisted skeins of albumen at either
end of the yolk, were not, as generally believed, the developing embryo,
and he demonstrated that the cicatricula (blastoderm) was the point of
origin of the embryo. The famous frontispiece of the treatise shows Zeus
holding an egg, from which issue animals of various kinds. On the egg is
written _Ex ovo omnia_, a legend since transmuted to the epigram _Omne
vivum ex ovo_. The legend illustrates Harvey's principal theme, repeated
constantly throughout the text, "that all animals were in some sort
produced from eggs."[20]
If Harvey made no contribution beyond emphasizing the origin of animals
from eggs, he would deserve a prominent place in the history of
embryology. But the work is also significant in its espousal of
epigenesis, and, supported as his argument was by observation and logic,
it became the prime formulation of that concept of development during
the seventeenth and eighteenth centuries. His statement of epigenetic
development is clear:
In the egg ... there is no distinct part or prepared matter
present, from which the fetus is formed ... an animal which is
created by epigenesis attracts, prepares, elaborates, and makes use
of the material, all at the same time; the processes of formation
and growth are simultaneous ... all its parts are not fashioned
simultaneously, but emerge in their due succession and order ...
Those parts, I say, are not made similar by any successive union of
dissimilar and heterogeneous elements, but spring out of a similar
material through the process of generation, have their different
elements assigned to them by the same process, and are made
dissimilar ... all its parts are formed, nourished, and augmented
out of the same material.[21]
Actually, Harvey's exposition of epigenesis, albeit clear, is not
totally impressive, since it is largely a reflection of Aristotle's
influence. The main importance of Harvey's vigorous and cogent defense
of epigenesis is that it provided some kind of counterbalance to the
increasingly dominant preformationist interpretations of embryonic
development.
Harvey did not break with Aristotelianism; on the contrary, he lent
considerable authority to it. Unable to escape the past, he was not
completely objective in his study of generation. Everywhere the pages of
his book reveal his indebtedness to past authorities. Robert Willis, who
provided the 1847 translation of _De Generatione_, expresses this well:
[Harvey] ... begins by putting himself in some sort of harness of
Aristotle, and taking the bit of Fabricius between his teeth; and
then, either assuming the ideas of the former as premises, or those
of the latter as topics of discussion or dissent, he labours on
endeavouring to find Nature in harmony with the Stagyrite, or at
variance with the professor of Padua--for, in spite of many
expressions of respect and deference for his old master, Harvey
evidently delights to find Fabricius in the wrong. Finally, so
possessed is he by scholastic ideas, that he winds up some of his
opinions upon animal reproduction by presenting them in the shape
of logical syllogisms.[22]
Even Harvey's concept of the egg reveals a strong Aristotelian bias.
Actually, Harvey attained to his conclusion that all animals derive from
eggs by assuming that
on the same grounds, and in the same manner and order in which a
chick is engendered and developed from an egg, is the embryo of
viviparous animals engendered from a pre-existing conception.
Generation in both is one and identical in kind: the origin of
either is from an egg, or at least something that by analogy is
held to be so. An egg is, as already said, a conception exposed
beyond the body of the parent, whence the embryo is produced; a
conception is an egg remaining within the body of the parent until
the foetus has acquired the requisite perfection; in everything
else they agree; they are both alike primordially vegetables,
potentially they are animals.[23]
The ovum, for Harvey, is in essence "the primordium vegetable or
vegetative incipience, understanding by this a certain corporeal
something having life in potentia; or a certain something existing _per
se_, which is capable of changing into a vegetative form under the
agency of an internal principle."[24] The ovum is for Harvey more a
concept than an observed fact, and, as stated by one student of
generation, "The _dictum ex ovo omnia_, whilst substantially true in the
modern sense, is neither true nor false as employed by Harvey, since to
him it has no definite or even intelligible meaning."[25]
Harvey's treatise on generation is clearly a product of his time. It
advances embryology by its demonstration of certain facts of
development, by its aggressive espousal of epigenesis and the origin of
all animals from eggs, and by its dynamic approach stressing the
temporal factors in development and the initial independent function of
embryonic organs. However, the strong Aristotelian cast of Harvey's
treatise encouraged continued discussion of long outdated questions in
an outdated manner and, combined with his expressed disdain for
"chymistry" and atomism, discouraged close cooperation between
embryologists of different persuasions. It is perhaps easy to
underestimate the impact and general importance of Harvey's work in view
of these qualifications, and so it should be remarked that both positive
and negative features of _De Generatione_ influenced profoundly
subsequent embryological thought.
It will be recalled that the title of _The Philosophicall Touch-Stone_
identified Digby as the object of Alexander Ross's ire. In comparable
manner, the latter's _Arcana Microcosmi_, published in 1652, declares
its purpose to be "a refutation of Dr. Brown's Vulgar Errors, the Lord
Bacon's Natural History, and Dr. Harvy's book _De Generatione_." Let us
pause a brief moment in memory of a man so intrepid as to undertake the
refutation of three of England's great intellects in one small volume,
and then proceed to examine the embryological concepts of one of the
trio, Sir Thomas Browne.
Browne's _Religio Medici_, composed as a private confession of faith
around 1635, is known to all students of English literature, as is his
later, splendid work on death and immortality, _Hydrotaphia,
Urne-Buriall_. One of the greatest stylists of English prose, Browne was
also a physician and a student of generation who deserves our attention
as an early chemical embryologist pointing the way to a form of
embryological investigation prominent in the last half of the
seventeenth century.
Browne's embryological opinions are found particularly in _Pseudodoxia
Epidemica_, _The Garden of Cyrus_, and in his unpublished _Miscellaneous
Writings_. Browne, a well-read man, was educated at Oxford, Montpellier,
Padua, and Leyden, and he was thoroughly imbued with the teaching of the
prophets of the "new learning." This is evident throughout his writings,
as witness his admonition to the reader of the _Christian Morals_:
Let thy Studies be free as thy Thoughts and Contemplations, but fly
not only upon the wings of Imagination; Joyn Sense unto Reason, and
Experiment unto Speculation, and so give life unto Embryon Truths,
and Verities yet in their Chaos.[26]
Browne greatly admired Harvey's work on generation, considering it "that
excellent discourse ... So strongly erected upon the two great pillars
of truth, experience and solid reason."[27] Browne carried out a variety
of studies upon animals of all kinds, in them joining Sense unto Reason,
and "Experiment unto Speculation." Thus in his studies of generation, he
made observations and also performed certain simple chemical
experiments. Noting that "Naturall bodyes doe variously discover
themselves by congelation,"[28] Browne studied experimentally the
chemical properties of those substances providing the raw material of
development. He observed the effects of such agents as heat and cold,
oil, vinegar, and saltpeter upon eggs of various animals, recording such
facts as the following:
Of milk the whayish part, in eggs wee observe the white, will
totally freez, the yelk with the same degree of cold growe thick &
clammy like gumme of trees; butt the sperme or tredde hold its
former body, the white growing stiff that is nearest it.... Egges
seem to have their owne coagulum within themselves manifested in
the incrassations upon incubation.... Rotten egges will not bee
made hard by incubation or decoction, as being destitute of that
spiritt, or having the same vitiated.... How far the coagulating
principle operateth in generation is evident from eggs wch will
never incrassate without it. From the incrassation upon incubation
when heat diffuseth the coagulum, from the _chalaza_ or gallatine
wh. containeth 3 nodes, the head, heart, & liver.[29]
It cannot be said that Browne attained to any great generalizations
regarding embryogeny on the basis of his rather naive experiments, but
they are indicative of the effects of the "new learning" in one area of
biology. Actually, Browne appears more comfortable in the search for
patterns conforming to the quincunx, as in _The Garden of Cyrus_, and
although he may well have been in search of something like the later
Unity of Type, he uses his amassed details of scientific knowledge most
effectively in support of nonscientific propositions. Thus, he uses the
facts of embryonic development, alchemy, and insect metamorphosis as a
part of his argument for the immortality of the human soul:
...for we live, move, have a being, and are subject to the actions
of the elements, and the malice of diseases in that other world,
the truest Microcosme, the wombe of our mother; for besides that
generall and common existence wee are conceived to hold in our
Chaos, and whilst wee sleepe within the bosome of our causes, wee
enjoy a being and life in three distinct worlds, wherin we receive
most manifest graduations: In that obscure world and wombe of our
mother, our time is short, computed by the Moone, yet longer than
the dayes of many creatures that behold the Sunne; our selves being
yet not without life, sense, and reason; though for the
manifestation of its actions it awaits the opportunity of objects;
and seemes to live there but in its roote and soule of vegetation;
entring afterwards upon the scene of the world, wee arise up and
become another creature, performing the reasonable actions of man,
and obscurely manifesting that part of Divinity in us, but not in
complement and perfection, till we have once more cast our
secondine, that is, this slough of flesh, and are delivered into
the last world, that ineffable place of Paul, that proper _ubi_ of
spirits. The smattering I have [in the knowledge] of the
Philosophers stone ... hath taught me a great deale of Divinity,
and instructed my beliefe, how the immortall spirit and
incorruptible substance of my soule may lye obscure, and sleepe a
while within this house of flesh. Those strange and mysticall
transmigrations that I have observed in Silkewormes, turn'd my
Philosophy into Divinity. There is in those workes of nature, which
seeme to puzzle reason, something Divine, and [that] hath more in
it then the eye of a common spectator doth discover.[30]
To affirm that Sir Thomas Browne was the founder of chemical embryology
or, indeed, to contend that he made a great impress upon the progress of
embryology is to humour our fancy. As Browne himself reminds us, "a good
cause needs not to be patron'd by a passion."[31] His work and
interpretations of generation are most important for our purposes as an
indication of the rising mood of the times and an emerging awareness of
the physiochemical analysis of biological systems. Although this mood
and awareness coexist in Browne's writings with a continued reverence
for some traditional attitudes, they mark a point of departure toward a
variety of embryological thought prominent in England during the second
half of the seventeenth century.
Browne did no more than analyze crudely the reaction of the egg to
various physical and chemical agents. This static approach was later
supplanted by a more dynamic one concerned primarily with the
physicochemical aspects of embryonic development. This is first apparent
in a report by Robert Boyle in the _Philosophical Transactions of the
Royal Society_ in 1666 entitled, "A way of preserving birds taken out of
the egge, and other small foetus's." Boyle, unlike Browne, exposed
embryos of different ages to the action of "Spirit of Wine" or "Sal
Armoniack," demonstrating thereby the chemical fixation of embryos as an
aid to embryology. A year later, Walter Needham, a Cambridge physician
who studied at Oxford in the active School of Physiological Research,
which included such men as Christopher Wren and Thomas Willis, published
a book reporting the first chemical experiments upon the developing
mammalian embryo.[32] Needham's approach and goals are more dynamic than
those of Browne, and he attempts to analyze various embryonic fluids by
coagulation and distillation procedures. His experiments reveal, for
example, that "coagulations" effected by different acids vary according
to the fluid; thus, the addition of "alumina" to bovine amniotic fluid
produced a few, fine precipitations, whereas the allantoic fluid was
precipitated like urine. By such means Needham was able to demonstrate,
however crudely, that there are considerable differences in the various
fluids occurring within and around the fetus. Furthermore, it is with
the results of chemical analyses that he supports his other arguments,
such as his contention that the egg of elasmobranchs is not, as
believed, composed of only one humour, but has separate white and yolk.
Needham's book contains many splendid observations, including an
accurate description of the placenta and its vessels, the relationship
of the various fetal membranes to the embryonic fluids, and rather
complete directions for dissection of various mammals. These need not
detain us, since the important aspect of Needham's work relevant to our
purpose is his continuation of the chemical analysis of the developing
embryo and its demonstration that, although Harvey might have despised
the "chymists" and been contemptuous of the "mechanical, corpuscular
philosophy," this system and approach was not to be denied.
Needham's book is dedicated to Robert Boyle, whose _Sceptical Chymist_
set the cadence for subsequent research based upon the "mechanical or
corpuscularian" philosophy and quantitative procedures. It is
appropriate for us, then, to terminate our discussion with a
consideration of this current in English embryological thought.
John Mayow was the first to realize that "nitro-aerial" vapour, or
oxygen, is essential to respiration of a living animal, and he was soon
led to inquire "how it happens that the foetus can live though
imprisoned in the straits of the womb and completely destitute of
air."[33] As a consequence of this interest, the third of his _Tractatus
Quinque medico-physici_, published in 1674, is devoted to the
respiration of the fetus _in utero_. He shows truly remarkable insight
when he concludes therein that
It is very probable that the spermatic portions of the uterus and
its carunculae are naturally suited for separating aerial particles
from arterial blood.
These observations premised, we maintain that the blood of the
embryo, conveyed by the umbilical arteries to the placenta or
uterine carunculae transports to the foetus not only nutritious
juice, but also a portion of the nitro-aerial particles: so that
the blood of the infant seems to be impregnated with nitro-aerial
particles by its circulation through the umbilical vessels in the
same manner as in the pulmonary vessels. Therefore, I think that
the placenta should no longer be called a uterine liver, but rather
a uterine lung.[34]
Although Mayow's attempted analysis of respiration of the chick embryo
_in ovo_ is less than successful, his views on fetal respiration were
soon accepted by many, and his tract stands as a great contribution to
physiological embryology.
The studies of such individuals as John Standard reporting the weight of
various parts of the hen's egg, e.g., the shell, the yolk, the white,
reveal the wing of embryological investigation that was increasingly
obsessed with quantification and the physicochemical analysis of the
embryo and its vital functions. In this they were following the
injunction of Boyle, who used the developing embryo as a vehicle in an
attack upon the idea that mixed bodies are compounded of three
principles, the obscurities of which operated to discourage
quantification:
How will this hypothesis teach us, how a chick is formed in the
egg, or how the seminal principles of mint, pompions, and other
vegetables ... can fashion water into various plants, each of them
endowed with its peculiar and determinate shape, and with divers
specifick and discriminating qualities? How does this hypothesis
shew us, how much salt, how much sulphur, and how much mercury must
be taken to make a chick or a pompion? And if we know that, what
principle it is, that manages these ingredients, and contrives, for
instance, such liquors, as the white and yolk of an egg into such a
variety of textures, as is requisite to fashion the bones, veins,
arteries, nerves, tendons, feathers, blood, and other parts of a
chick? and not only to fashion each limb, but to connect them all
together, after that manner, that is most congruous to the
perfection of the animal, which is to consist of them?[35]
The emphasis upon quantification and the physicochemical analysis of
vital processes was to continue into the eighteenth century and to
contribute to the great stress upon precision in that period. It was
not, however, destined to become immediately the main stream of
embryological investigation. For even as the studies of Mayow were in
progress, embryology was embarked upon a course leading to
preformationism. By the end of the seventeenth century, the idea that
the embryo was encased in miniature in either egg or sperm was elevated
to a position of Doctrine, and thereafter there was little encouragement
to quantitative study of development. Many embryological investigations
were performed during the eighteenth century, but most relate to the
controversy regarding epigenesis and preformationism as the true
expression of embryonic development. Withal, the seventeenth-century
embryologists, and particularly the embryologists of seventeenth-century
England, had contributed much to the progress of the discipline. They
had introduced new ideas, applied new techniques, and created new
knowledge; they had effectively advanced the study of development beyond
the stage of macro-iconography; they had freed the discipline from much
of its traditional baggage of causes, virtues, and faculties. Various
English embryologists had varying success with developmental theory, but
as a group they had made great impact upon the development of
embryology. In the course of their century, they had, in the words of
one of them, "called tradition unto experiment."[36]
_Notes_
[1] Charles Dickens, _A Tale of Two Cities_, London, 1859, p. 1.
[2] Kenelm Digby, _Private Memoirs of Sir Kenelm Digby, Gentleman of the
Bedchamber to King Charles the First_, London, 1827, Preface, p. i.
[3] Kenelm Digby, _Two Treatises, in the One of Which, The Nature of
Bodies; in the Other, the Nature of Mans Soule; is Looked into_, Paris,
1644, p. 213.
[4] _Ibid._, p. 220.
[5] _Ibid._, pp. 220-221.
[6] _Ibid._, p. 222.
[7] _Ibid._, p. 215.
[8] _Ibid._, p. 219.
[9] _Ibid._, p. 213.
[10] _Ibid._, pp. 217-219.
[11] _Ibid._, p. 231.
[12] Alexander Ross, _The Philosphicall Touch-Stone; or Observations
upon Sir Kenelm Digbie's Discourses of the nature of Bodies, and of the
reasonable Soule_, London, 1645.
[13] Alexander Ross, _Arcana Microcosmi: or, The hid secrets of Man's
Body disclosed ... In an anatomical duel between Aristotle and Galen
concerning the parts thereof_, London, 1652, p. 87.
[14] Nathaniel Highmore, _The History of Generation, Examining the
several Opinions of divers Authors, expecially that of Sir Kenelm Digby,
in his Discourse of Bodies_, London, 1651, p. 4.
[15] _Ibid._, pp. 26-27.
[16] _Ibid._, pp. 27-28.
[17] _Ibid._, p. 45.
[18] _Ibid._, Pp. 90-91.
[19] William Harvey, _Opera omnia: a Collegio Medicorum Londinensi
edita_, Londini, 1766, p. 136.
[20] William Harvey, _Anatomical Excercises on the Generation of
Animals_, trans. Robert Willis, London, 1847, p. 462.
[21] _Ibid._, pp. 336-339.
[22] _Works of William Harvey_, trans. Robert Willis, London, 1847, pp.
lxx-lxxi.
[23] Harvey, _op. cit._, pp. 462-463.
[24] _Ibid._, p. 457.
[25] F. J. Cole, _Early Theories of Sexual Generation_, Oxford, 1930, p.
140.
[26] Thomas Browne, _The Works_, ed. Geoffrey Keynes, Chicago, 1964, I,
261-262.
[27] _Ibid._, II, 265.
[28] _Ibid._, III, 442.
[29] _Ibid._, III, 442-452.
[30] _Ibid._, I, 50.
[31] _Ibid._, I, 14.
[32] Walter Needham, _Disquisitio anatomica de formato foetu_, London,
1667.
[33] John Mayow, "De Respiratione foetus in utero et ovo," in _Tractatus
Quinque Medico-Physici_, Oxonii, 1674, p. 311.
[34] _Ibid._, pp. 319-320.
[35] Robert Boyle, _The Works_, London, 1772, I, 548-549.
[36] Browne, _op. cit._, II, 261.
II
_Robert Boyle as an Amateur Physician_
LESTER S. KING
Robert Boyle was not a physician. To be sure, he had engaged in some
casual anatomical studies,[37] but he had not formally studied medicine
and did not have a medical degree. Nevertheless, he engaged in what we
would call medical practice as well as medical research and exerted a
strong influence on the course of medicine during the latter seventeenth
century, an influence prolonged well into the eighteenth. He lived
during the period of exciting yet painful transition when medical theory
and practice were undergoing a complete transformation towards what we
may call the "early modern" form. The transition, naturally gradual,
extended over three centuries, but I wish to examine only a very small
fragment of this period, namely, the third quarter of the seventeenth
century.
Boyle's first major work which dealt extensively with medical problems
was the _Usefulness of Experimental Philosophy_. This work, although
published in 1663, had been written in two parts, the first much earlier
than the second. Fulton[38] indicates it had been drafted around 1650,
while Hall[39] ascribes it to the period 1647-1648. This first part has
relatively little to do with medicine; the references are few and rather
incidental, and have significance only for the light they throw on
"natural philosophy" and "natural religion." The second part, however,
written apparently not too long before publication, has a great deal to
do with medicine and constitutes one of the important medical documents
of the century.