THE EVIDENCE FOR A SCIENTIFIC "PARADIGM"
Before the "revolutionary implicatons" of Lake's assertions can be seriously considered, the underlying validity of the paradigm" itself must be verified. Is there evidence to corroborate the central assertions of the M-FDS so as to allow it to be generally accepted as a system of ideas giving definition to the problems and methodology of psychodynamics?1
The methodology required to answer this question first necessitates some kind of central definition of what is being affirmed so that it can be accepted or rejected based upon the evidence. Thus stated, the M-FDS has been defined in the following manner: "the behavioral reactions of a pregnant mother affect her fetus in ways that contribute to its perceptions of itself and of its environment in the womb; and these perceptions persist into adult life."2
This definition, however, is inadequate for our purposes because fetal
perceptions of the self and the environment are incapable of being ascertained. That adult perceptions of the self and the environment are based somewhat on the fetal experience may be true, but again, it is impossible to ascertain their origin. Thus, for the purposes of this endeavor, the general definition of a maternal-fetal syndrome is as follows: "the fetal environment as mediated by the mother affects fetal movement, sensation, memory, learning, affect, and behavior."
At its most basic level, the M-FDS is simply stating that the environment of the pre-born baby influences his or her psychological development in both the immediate and long-term senses. That this is assumed to be true of postnatal existence, even of infants, is generally accepted. Wide-ranging research studies have clearly shown the effect of both positive and negative environmental influences on subsequent perception and behavior.
If the same is to be said regarding prenatal experience, as Lake affirms, then the same or similar mechanisms that allow such influences to occur postnatally must be shown to exist prenatally. What allows environmental influence postnatally is the ability of an organism to
1Moss, ~Frank Lake's Maternal-Fetal Distress Syndrome and the Primal Integration Workshops-Part II."
2Moss, "Frank Lake's Maternal-Fetal Distress Syndrome: Clinical and Theoretical Considerations," 204.
Further, can the pre-born not only apprehend the environment, but also express themselves to the environment through crying, motor movement, and facial expressions? Is there such a thing as a prenatal personality?3 If the above questions can be substantially demonstrated in the affirmative by the evidence, then it could be said that the structure and mechanisms which would allow for the M-FDS to exist are indeed present.
Two lines of "evidence" are examined in this chapter. The first is a brief examination of the historical precedence to some of the main ideas Lake postulates. The second and largest body of evidence examined is the research documentation for embryological and fetological aptitudes with regard to the various morphological and psychological dimensions.
apprehend the environment, this through the senses and nervous system. Thus, the same applies prenatally. Is the brain and nervous system sufficiently developed to allow for neural transmission? Are the various specialized neural sense receptors capable of visual, tactile, auditory, gustatory, and olfactory sensation? Is the nervous system sophisticated enough to allow for intermodal fluency between the senses, for cognition, memory, learning, habituation, imitation, conditioning, and emotions?
a. Early Western Thought
A. Historical Precedence for Lake's M-FDS
1. Pre-20th Century Embryological and
The idea that the prenatal environment affects the developing organism is certainly not new or original with Frank Lake. Many early thinkers speculated, some accurately and others mistakenly, regarding fetal behavior and psychology as well as the influence of maternal
and/or environmental determinants of fetal outcomes. Democritus and Epicurius both surmised
3A.W. Liley writes: "One dictionary offers [as a definition for personality] 'what constitutes an individual as a distinct person,' but does not define what the 'what' is. Another dictionary assens 'the state of existing as a thinking intelligent being.' This definition might lead to the inference that personality increases 'pro rata' with Intelligence. . . . My copy of Ken Stallworth's Manual of Psychiatry (Christchurch, N.Z.: Peryer, 1950) is more help with the definition that 'personality is the individual as a whole with everything about him which makes him different from other people,' because we can certainly distinguish foetuses from each other and other people. With the next sentence - 'personality is determined by what is born in the individual in the first place and by everything which subsequently happens to him in the second' - we are really in business. Not only can I tell you what is apparent of what is born in the foetus, but I can also describe the environment in which he lives, the stimuli to which he is exposed, and the responses which he displays." (A.W.Liley, "The Fetus as Personality," Pre- and Peri-Natal Psychology Journal 5 : 191).
With the work of Hippocrates and those associated with him, namely his son-in-law Polybus, embryology takes a great leap forward, particularly with his treatise On Semen and on the Development of the Child. Hippocrates rightly surmises that it is the maternal blood flow which nourishes the embryo. Further, the umbilical cord is associated with fetal respiration.7
During the next century (4th c. BC), Diodes of Carystus in Euboea extended embryological thought through his examinations and dissections of fetal remains. He reported that he had found traces of the head and spinal cord in a 27-day-old embryo and was able to clearly distinguish the human form at 40 days.8
With the possible exception of Hippocrates, Aristotle stands out among the early Western thinkers as the most important advancer of embryological science. Due to his extensive dissections of various animals and animal embryos, his observations filled several major works of general and comparative biology and embryology, among them
that the embryo ate and drank "per os"4 Plutarch later compared these views to that of the earlier Alcmaeon who postulated a "sponge" theory of prenatal nourishment.5 Writing about the same time Empedocles theorized regarding the origin of twins, but very interestingly also affirmed the profound influence of the maternal imagination upon the fetus to the point that it could be guided and interfered with at will.6
4D. Gupta and B. Datta "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development." in Prenatal and Perinatal Psychology and Medicine, ed. Peter G. Fedor-Freybergh and M.L. Vannessa Vogel (Park Ridge, NJ: The Parthenon Publishing Group, 1988), 514.
5Plutarch wrote: "Democritus and Epicurius hold that this imperfect fruit of the womb receiveth nourishment at the mouth. . . . But AIcmaeon affirmeth that the infant within the mother's wombe, feedeth by the whole body throughout for that it sucketh to it and draweth in a manner of a sponge." (Plutarch, Moralis, trans. Philemon Holland [London: Hatfield, 1603]; quoted in Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 514).
6H. Diels, Fragmente der Vorsokratiker (Berlin, 1906), quoted in Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development,"
7T.U.H. Ellinger, Hippocrates on lntercourse and Pregnancy (New York: Schuman, 1922), quoted in Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 515.
8Clifford AIlbutt, Greek Medicine in Rome (London: Macmillan, 1921), quoted in Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 516.
Following Aristotle, embryological understanding in the western tradition stagnates or, in the cases of the Stoicism and Epicureanism, even regresses. There are, however, several persons of note. Herophilus of Chalcedon, a member of the Alexandrian School and writing in the 3rd c. BC made many dissections of embryos and described in some detail the ovaries, Fallopian tubes, and the umbilical cord.13
In addition to Greek thinkers, two Romans14 also made contributions toward the understanding of embryology that lasted well into the Middle Ages. In the first c. AD, Sorenus
On the Generation of Animals, The History of Animals, On the Parts of Animals, On Respiration, and On the Motion of Animals. He correctly understood the nature of fetal nutrition9 and he anticipated several important aspects of embryology, among them genetics10 and enzyme actions.11 Interestingly Aristotle also speculated that sensation is first acquired during
9Aristotle, Generation of Animals, trans. and ed. James Loeb (Cambridge, Mass: Harvard Univ. Press, 1942), 740a 24-740b 14 (197-199); 746 a20-28 (241-243).
10The end is developed last, and the peculiar character of the species is the end of the generation in each individual. This means that the embryo attalns the point of being definitely not a plant before it attalns that of being definitely not a mollusc but a horse or man." Aristotle, Generation of Animals, quoted in Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 518.
11"The action of the semen of the male in "setting" the female's secretion in the uterus is similar to that of rennet upon milk. Rennet is milk which contains vital heat, as semen does. and this integrates the homogeneous substance and makes it "set." As the nature of milk and the menstrual fluid is one and the same, the action of the semen upon the substance of the menstrual fluid is the same as that of rennet upon milk. Thus when the "setting" is effected, ie. when the bulky portion "sets," the fluid portion comes off; and as the earthly portion solidifies membranes form all round its outer surface." (Aristotle. Generation of Animals, 739b 22, [191-193]).
12"Having settled upon these points we may proceed to those which immediately follow. First then: the habit of the young of all animals, especially those of animals which bring forth their young imperfect, once they have been born, is to sleep, because they are in fact continually asleep within the parent from the time they first acquire sensation [emphasis mine]." (ibid.. 778b20-25; see also 736a30-736b25).
13Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 529.
14Gupta and Datta also write the following: "The name of the Ptolemaic queen, Cleopatra (who died in the year 30 BC), is also mentioned for carrying out investigations on the fetal developmental processes. However, this is legend and the source of it cannot be traced. It is said that Queen Cleopatra continued such investigations by dissecting live female slaves impregnated by prison guards at known intervals of time from conception - following the procedure of Hippocrates with regard to hen's eggs. This Alexandrian experiment established that the male fetus was complete in 41 days and the female in 81." (Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 530-531).
The second Roman of note was Galen, who lived in the 2nd c. AD and wrote three works touching on embryology with the intriguing titles of On the Anatomy of the Uterus, On the Formation of the Fetus, and On the Question as To Whether the Embryo is an Animal.17 Galen called the process of intrauterine life or embryology "genesis" and while much of his descriptions of it are inaccurate, he alludes to the processes histogenesis18 and
organogenesis19 (or growth and differentiation) as "alteration" and "shaping" or "molding."20 The period of "genesis", according to Galen, includes four distinct stages21 and parallel to this development, "the embryo also rises from possessing the life of a plant to that of an animal."22
of Ephesus wrote a book titled On the Disease of Women, which, although largely obstetrical, also shows an advanced understanding of embryology.15 Tertullian, arguing that the fetus is
already a living being in the uterus, stated "Soranus . . . [was] sure that a living creature had been conceived,"16 thus implying at least a rudimentary acknowledgement of the separate life of the fetus.
15Soranus of Ephesus, Die Gynakologie der Soranus von Ephesus, trans. H. Luneberg (Munich, 1894), quoted by Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 530.
16TertuIlian, quoted in Ralph Jackson, Doctors and Diseases in the Roman Empire (Norman OkIa: Univ of Oklahoma Press, 1988), 109.
17Galen, On the Usefulness of the Parts of the Body, vol. 2, trans. Margaret Tallmadge May (Ithaca, N.Y.: Cornell Univ. Press, 1968), 655-680.
19The ordering of tissue into organs.
20"Genesis, however, is not a simple activity of Nature, but is compounded of alteration and of shaping. That is to say, in order that bone, nerve, veins, and all other [tissues] my come into existence, the underlying substance from which the animal springs must be altered, and in order that the substance so altered may acquire its appropriate shape and position, its cavities, outgrowths, attachments and so forth, it has to undergo a shaping or formative process." (Galen, On the Natural Faculties, trans. Arthur John Brock [Cambridge, Mass.: Harvard Univ. Press, 1963], 19).
21(1) an unformed seminal stage; (2) a stage in which the "tria principia" are engendered, the heart, liver and brain; (3) a stage when all the other parts are mapped out, and (4) a stage when all the other parts have become clearly visible." (ibid., quoted in Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning
Conception and Embryo Development," 532).
Parallel to and even preceding the early Greek and Roman embryological advances, was an active tradition of non-westem speculation regarding embryological and fetal processes. Most prominent among them are a group of Indian theorists, the earliest being Susruta, around the late 6th or early 5th century BC.
Similar to the early Greek and Roman thinkers, much of the speculation is faulty, but much anticipates later discoveries. Modern genetics is prefigured with Susruta's affirmation that "the bodily and mental characteristics of the future child, whether manifest or latent, are pre-determined."23 He divided the "genetic" contributions of each parent according to sex, with the father contributing the "stable and firm components" of the body (ie. hair, nails, bones, nerves, arteries, veins, teeth, tendons and semen) while the "soft components" (blood, fat, muscles, heart, bone-marrow, liver, spleen, intestines, umbilicus, rectal parts, and sex organs) result from the mother's "genetic" contribution. Emerging from the "physiological and spiritual harmony" of the parents are the "genetic" characteristics of intellect, health, valour, constitution, and "brightness of complexion."24
Susruta also clearly articulated a sophisticated understanding of interdependency of the feto-placental unit, both physiologically and psychologically. He noted that nourishment from the mother's body begins by means of the umbilical cord as soon as the fetus is "endowed with life"25 and advocated a variable diet for mother and child depending upon the needs of the growing fetus.26
In addition, Susruta maintained an understanding of the impact of the mother's psychological state upon the emerging fetus. Following the third month when all the major limbs and organs are present in their rudimentary forms, Susruta states that the fetus acquires a consciousness of its surroundings and begins to "long for" sense objects.
b. Early Non-western Thought
23Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 521.
24Susrutasamhita Susruta, Sanrasthanam and Cikitsasthanam, ed. Ambikadatta Sastri (Benares: Chowkhanba Sanskrit Series Office, 1954) 3.31, quoted in Gupta and Datta "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development." 521.
25ibid., 3.17, 524.
26During the first 3 months the diet should be rich in cooling and sweet products with a preponderance of liquid foods. During the third month the best quality of rice should be taken with milk. For the next 2 months milk and yogurt were suggested. From the fourth month onwards generous quantities and milk and milk products, good quality soup and light meat preparations were prescribed." (ibid., 10.3, 524).
These "longings" are imparted to the mother and are expressed externally through the mothers "desires." If the exchange is short-circuited and these desires are denied, suppressed or remain unfulfilled, then the effect on the fetus can be profound. According to Susruta, various congenital defects such as paralysis, dwarfism, blindness, various sense organ defects and lameness can be the result.27
That Susruta maintains some sort of fetal psychology is clear. Along with the above stated affirmations of consciousness and sense perception, the fifth month results in the acquisition by the fetus of a "mind of its own" and is said to "awaken." This is quickly followed by the realization of an "intellect" in the 6th month.28
A second prominent early Indian thinker in the area of embryology is Caraka.29 Caraka shares similar theoretical notions with Susruta regarding the "genetic" contributions of the mother and father to the developing fetus. From the mother come the "skin, blood, flesh, fat, navel, heart, kloma, liver, spleen, kidneys, urinary bladder, colon, stomach, intestine, rectum, anus, small intestines, large intestines, omentum, and mesentery"30 while the father contributes the "head-hairs, beards-mustaches, nails, body hairs, teeth, bones, ligaments, and semen.31 The fetus' appetite, vitality, clarity of senses, and quality of voice all arise out of parental harmony32 while the qualities of "life-span, self knowledge, mind, sense organs, respiration, impulse, sustenance, characteristic physiognomy, voice and complexion, happiness, misery, desire-aversion, consciousness, restraint, intellect, memory, ego and will."
27ibid., 3.15, 523.
28ibid., 3.28; 5.523.
29According to Gupta and Datta various dates for Caraka have been proposed on the basis of internal and external evidence. They cite P.C. Ray's History of Hindu Chemistry, (vol.1) (London: Oxford Univ. Press, 1902) which places Caraka in the "pre-Buddhist age, i.e. before the 6th century BC." (Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development", 525). However, Zysk states the following: "Controversy exists over the exact date of Caraka, with many scholars subscribing to the view of Sylvaln Levi. who, on the authority of the fifth-century C.E. Chinese translation of the Sutalamkara, asserted that Caraka was a physician of King Kaniska, thus placing his treatise in the first or second century of the common era." (Kenneth Zysk, Asceticism and Healing in Ancient India New York: Oxford Univ Press, 1991], 331).
30Caraka, The Caraka-samhita of Agnivesa, vol.1 (Sarirasthanam), annotated by Caraka and redacted by Drdhabala, ed. and trans. Priyavrat Sharma (Delhi: Chaukhambha Orientalia, 1982), 3.6., 421.
31ibid., 3.7, 421.
32ibid., 3.11, 423.
are cause by the fetus' self",33 known as "jiva".34
Caraka also shared with Susruta an understanding of the cruciality of fetal
nourishment. He maintains that the child's shape, vigor, energy and sense of contentment all arise as a result of proper nourishment.35
According to Caraka, the physiological process of embryonic and fetal development proceeds from that of "shapeless jelly" the first month to being "tumor-like" or fleshy the
second to limb and sex-organ differentiation the third month and so on.36 Caraka believed the fetus' and mother's hearts to be connected through the umbilical cord and placenta, transmitting nourishment through the blood, as well as "vitality and complexion."37 Caraka believed that the fetus could be destroyed, deformed, or suffer psychologically due to physical or emotional disturbances of the mother.38
Indeed, Caraka was very aware of the possible prenatal psychological
influences on the emerging child's psyche and lists a comprehensive catalogue of possible mental stress, shocks, and maternal habits which might cause psychological damage to the fetus.39 He concludes this section with this conclusion:
Thus the facts causing damage to the fetus are said. Hence the woman
desiring excellent progeny should particularly abstain from the unwholesome
diet and behavior. Observing good conduct, she should manage herself with the
wholesome diet and behavior.40
33ibid., 3.10, 423.
34Defined as the "source of life." (ibid., 3.6, 421).
35ibid., 3.12, 423.
36ibid., 4.9-25, 430-433.
37ibid., 6.23, 452.
38ibid., 4.15-33, 431-435.
39Caraka alludes to the various possibilities of psychological effects from the mother to the fetus. He writes, "The woman sleeping In open places and moving out in the night gives birth to an insane; If she indulges in quarrels and fights, the progeny will be epileptic. One indulged in sexual intercourse to ill-physiqued, shameless, and devoted to women; one always under grief to timid, undeveloped or short-lived; one thinking ill of others to harmful, envious, or devoted to women; the thief to exerting, wrathful or inactive; the intolerant to fierce, deceitful and jealous; one who sleeps constantly to drowsy, unwise and deficient in digestive power; one who takes wine constantly to thirsty, poor in memory and unstable in mind. . . . The pregnant woman gives birth to a child suffering mostly from the respective disorders the etiological factors of which are used by her." (ibid., 8.21, 468).
In addition to Susruta and Caraka, other Indian thinkers also made various embryological speculations. Most are repetitions of one sort or another of Susruta and Caraka. However, for the purposes of this dissertation, it is significant that there was congruity on the subject of a fetal psychology, especially as it relates to sense perception and consciousness. Parasra writes:
As such, Caraka certainly anticipates Lake's M-FDS.
During the sixth month, holes appear in the ears of the embryo. During the seventh month vessels, ligaments, bones, phalanges, hair on the head, nails and skin appear on the embryo. the embryo becomes more conscious during this month.41
Following Galen, the advance of embryology and fetology is, at least in the Western tradition, arrested for almost 13 centuries. While several works do occur, they are essentially composed of restatements or compilations of Hippocrates, Aristotle, Sorenus and Galen.42
Perhaps one exception to this is Trotula's 11th century text on various gynecological ailments and their cures.43 Trotula, thought to be a woman, was associated with the medical school in Salerno, Italy. Her work was not available in an English translation until the middle of the 15th century but still preceded by almost a century what was at one time thought to be the earliest obstetrical text to appear in English, The Byrth of Mankynde, translated from Eucharius Rosslin's Der Swangern Frawen und Hebammen Rosegarten,44 first published in 1513 and first appearing in English in 1540.
C. Medieval and Early Modern Thought
41Parasara. Parasarasmrti, ed. Daivajnavacaspati Sri Vasudeva (Benares: Chowkhamba Sanskrit Series Office, 1968), quoted in Gupta and Datta, "The Cultural and Historical Evolution of Medicine and Psychological Ideas Concerning Conception and Embryo Development," 527.
42For instance. Albertus Magnus' Da animalibus from the 13th century which is basically a close restatement of Aristotle, especially as it relates to areas of embryological interest. He also cites Galen extensively.
43Trotula, Medieval Woman's Guide to Health, trans. and ed. Beryl Rowland (Kent, Ohio: Kent State Univ. Press, 1981).
44Eucharius Rosslin, Der Swangern Frawen und Hebammen Rosegarten. ed. Gustav Klein (Munich, C. Kuhn, 1910).
Similar to the medieval period, various derivative works continued to appear in the 15th and 16th centuries. However, several small advances began to appear,45 including Leonardo da Vinci's embryological and fetological statements, drawings and illustrations.46 With the
publication in 1604 of Hieronymus Fabricius' De formato Feotu,47 the description and
illustration of the physiological dimension of embryology and fetology48 takes a great leap. But this publication, and the ones preceding and it, contain little if any speculation regarding the existence of a fetal psychology.
Up until the 16th century, the prevailing view of embryological development was the epigenetic, that the various components of the developing creation occurred sequentially. The historic weakness to this conceptualization is that it did not adequately account for the complex mechanism of the "creation" of life itself.49 A less dominant but plausible rival view was the preformation theory, which argued that embryonic life in miniature already existed within the parent and thus development consisted simply in growth, not creation.50
Such an argument, postulated early on by Plato and Aeschylus among others, came into vogue during the late 16th century. But because of the inability to locate an ovum or sperm in the uterus, the epigenetic line of reasoning was revived by some. William Harvey, for instance, in his important 1651 work De generatione animalium, takes this view.51
45Alexander Benedictus, Histona corpus humani sive Anatomice, (Venetiis: A Bernadino Guerraldo Vercellensi, 1502); Andreas Vesalius fle humani oorpons faori~a (Basileae: Ex officina 10. Oporini, 1543); Realdus Columbus De re anatomica (Venetiis: Ex typographia Nicolal Bevilacquae, 1559); Bartholomaues Eustachius Opuscula anatomica ("enetils: Vincentius Luchinus, 1563); Gabriel Fallopius, Observationes anatomicae (Venetiis: Apud Marcum Antonium Ulmum, 1561); Julius Ceasar Arantius De humano foetu liber tertio editus (Venetiis: Apud lacobum Brechtanum, 1587).
46Leonardo da Vinci, The Drawings of Leonard da Vinci, ed. A.E. Popham (New York: Harvest Books,1945).
47Hieronymus Fabricius, The Embryological Treatises of Hieronymus Fabricius, trans. and ed. Howard B. Adelmann (Ithaca, N.Y.: Cornell Univ. Press, 1942).
48Cunningham writes that Fabricius' work is less on embryology and more on comparative "generation" because of his focus almost exclusively on the "procreation and formation of the fetus." (Andrew Cunningham, "Fabricius and the 'Aristotle Project" at Padua," in The Medical Renaissance of the Sixteenth Century, eds. A. Wear, R.K. French and I.M. Lonie (NY: Cambridge Univ. Press, 1985), 210.
49Angus McLaren, "The Pleasures of Procreation: Traditional and Biomedical Theories of Conception," in William Hunter and the Eighteenth-Century Medical World, eds. W.F. Bynum and Rhea Porter (New York: Cambridge Univ. Press, 1955), 333.
The period of the end of the 17th through the end of the 19th century brings about significant technical and "physical" advances in embryology and fetology. With the availability of the microscope at the close of the 17th century, the sperm was first seen by Hamm and Leeuwenhoek in 1677 following by five years the observation of the ovarian follicles by de Graff.52 Thus, the preformation theory again begins to prevail, but is split between two camps, the animalculists and the ovists, the latter holding that the miniature offspring was to found in the ovum and the former that it was to be found in the sperm.53 The preformationist view in its various manifestations predominated until at least the middle of the 18th century.
It is also during this period that some speculation regarding fetal cognition and understanding takes place. John Locke, writing in his Essay Concerning Human Understanding speculated that the capacity to form ideas may be characteristic of fetal life.54 Jean-Jacques Rousseau, writing in the next century, alternately regarded the fetus as a "witless tadpole" eventually born with a "tabula rasa" for a mind.55
The late 18th century brings some important advances, including Spallanzani's application of the experimental method to embryology which finally demonstrates that both the ovum and sperm are necessary for conception to occur.56
This discovery, along with a general lack of evidence for the preformation theories results in a switch back to the epigenetic argument, this time permanently, although this change was quite gradual. For instance, Wolff sets forth his conceptualization of epigenesis,57 a method of progressive growth and differentiation from the simpler to the more complex, through the utilization of basic building units called "globules" or cells.58
The preformationist theory was permanently laid to rest in 1900 by Driesch who showed that forms of the cells of a fertilized egg, can, when
separated, develop into complete embryos.59 The present view is that "development is strictly preformational as regards the genes and their hereditary influences, but rigorously epigenetic in actual constructional activities."60
The late 18th through 20th centuries brings many technical advances. For instance, William Hunter's Treatise on the Human Gravid Uterus in published in 1774 and is an important advance in embryological and fetal observation and illustration. Von Bauer finally clearly identifies the mammalian egg in 182751 while Schleiden and Schwann lay the foundations of modern embryology with the formation of cell theory.52 Wilhelm His' book The Anatomy of Human Embryos, published in 1880, stands as the first great modern work dealing with specifically human embryology.63
52Bradley M. Patten, Human EmbryoIogy (Philadelphia: The Blakiston Company, 1946), 2.
53McLaren, "The Pleasures of Procreation: Traditional and Biomedical Theories of Conception," 333.
54John Locke, Essay Concerning Human Understanding (Chicago: Henry Regnery Co, 1956). Locke's treatise was originally published in 1690.
55Peter G. Hepper, "Foetal Learning: Implications for Psychiatry?" British Journal of Psychiatry 155 (1989): 289.
56Patten, Human EmbryoIogy, 3.
58Leslie Arey, Developmental Anatomy (Philadelphia: W.B. Saunders Co., 1954), 4.
62Patten, Human Embryology, 3.