Parthenogenesis is a form of asexual reproduction in which a gamete (ovum or sperm) develops without being fertilized. Tomer Jordi Chaffer uses parthenogenesis to challenge Don Marquis' future-like-ours (FLO) argument against abortion. According to Marquis, (1) what makes it morally wrong to kill us is that it would deprive us of a possible future that we might come to value—a future “like ours” (FLO) and (2) human fetuses are numerically identical to any adult human organism they may develop (...) into, and thus have a FLO. Chaffer contends that if human ova are capable of parthenogenesis, then they would have a FLO, which contraception may deprive them of, but contends this is absurd. Bruce P. Blackshaw challenges Chaffer, contending sexually fertilized embryos are not identical to unfertilized ovum, but this would yield a more absurd implication, that fertilization deprives an ovum of a FLO! Here I show Marquis' account of identity rules out both Chaffer's and Blackshaw's accounts. (shrink)

The aim of regenerative medicine is to reconstruct tissue that has been lost or pathologically altered. Therapeutic cloning seems to offer a method of achieving this aim; however, the ethical debate surrounding human therapeutic cloning is highly controversial. Artificial parthenogenesis—obtaining embryos from unfertilised eggs—seems to offer a way to sidestep these ethical pitfalls. Jacques Loeb , the founding father of artificial parthogenesis, faced negative public opinion when he published his research in 1899. His research, the public’s response to his (...) findings, and his ethical foundations serve as an historical argument both for the communication of science and compromise in biological research. (shrink)

The present work is a contribution to the understanding of the sempiternal problem of the “burden of factor two” implied by sexual reproduction versus asexual one, as males are energy consumers not contributing to the production of offspring. We construct a deterministic mathematical model in population dynamics where a species enjoys both sexual and parthenogenetic capabilities of reproduction and lives on a limited resource. We then show how polygamy implies instability of a parthenogenetic population with a small number of sexually (...) born males. This instability implies evolution of the system towards an attractor involving both populations. We also exhibit the analogy with a parasite/host system. (shrink)

This paper examines the contents and institutional context of August Weismann's long essay on Amphimixis (1891). Therein he presented detailed discussions of his on-going studies of reduction division and parthenogenesis, but more to the point, he included an elaborate examination of Émile Maupas's two major publications in protozoology. To understand the relevance of this part to the other two, the author briefly reviews highpoints in earlier nineteenth century protozoology and concludes that only in the mid-1870s and 1880s did protozoa (...) add an important dimension to heredity theory. Otto Bütschli and then Maupas provided Weismann with a deeper understanding of how conjugation and fertilization were related but not identical processes. This allowed him to integrate the two into a fuller understanding of evolution by natural selection. (shrink)

In his 1987 book "Controlling Life: Jacques Loeb and the Engineering Ideal in Biology", Philip Pauly presented his readers with the biologist Jacques Loeb and his role in developing an emphasis on control of life processes. Loeb's work on artificial parthenogenesis, for example, provided an example of bioengineering at work. This paper revisits Pauly's study of Loeb and explores the way current research in regenerative medicine reflects the same tradition. A history of regeneration research reveals patterns of thinking and (...) research methods that both echo Loeb's ideology and point the way to modern studies. Pauly's work revealed far more than we readers realized at the time of its publication. (shrink)

When in doubt, for the embryo. New arguments on the moral status of human embryos. - In the first part of our essay we distinguish the philosophical from the legal and political level of the embryo debate and describe our indirect justification strategy. It consists in renouncing a determination of the dignity-giving φ-properties and instead starting from premises that are undoubted by all discussion partners. In the second part we reconstruct and criticize the species, continuum, identity and potentiality arguments. The (...) species argument only has a certain plausibility, if at all, as a critical argument. From the continuum argument and identity argument we take over the idea of numerical identity (NI) and link it with the core idea of the potentiality argument (P). So we come to the NIP argument: -/- (NIP) -/- (1) Every living human body that is the bearer of (or has) potential φ-properties has dignity. (2) Every viable human embryo is a living human body that is the bearer of (or has) potential φ properties. Therefore, (3) Every viable human embryo has dignity. -/- Reversibly comatose people and newborns are protected because they have the potential to have actual personal characteristics in the future; our thesis is that embryos that are capable of development also have the same potential in moral terms. The basic idea of numerical identity, with which we support the second premise, is that every human being, from embryonic existence to adulthood, forms a physical unity. In a detailed part, we deal with the crown princess, gametes, parthenogenesis, somatic cell, pronuclear stage, biological heteronome early embryo, multiple, fusion, Siamese twin, hydatidiform mole and finally trophoblast problems. In a third part, the indirect argument is supplemented by a metatheoretical cautionary argument. It states that in situations where there is doubt as to whether a being falls within the scope of a moral norm, but there are sufficiently strong reasons for this subsumption, it must be assumed that this is the case if the contrary assumption and the positive effects it may have are in no acceptable proportion to the moral harm that would result if that subsumption were not made. The main result of our considerations is therefore: When in doubt, for the embryo. (shrink)

This paper examines the metaphors of 'preformation' and 'epigenesis' in Kant's Critique of Pure Reason and his other references to and various uses of theories of biological generation. It asks what these metaphor are meant to do, philosophically, and whether the idea of epigenesis, in particular, can help explain the specificity of transcendental idealism in relation to empiricism, or whether it illuminates anything concerning the status or the function of the categories. Discussing the most important interpretations of the epigenesis metaphor (...) in the Critique of Pure Reason by Philip Sloan, Günter Zöller and John Zammito, this paper suggests an alternative interpretation of the generative metaphorics surrounding Kant’s presentation of the spontaneous production of the pure concepts by the understanding. Placing the single reference to epigenesis in Critique of Pure Reason in the context of the book’s larger set of metaphors of generation, birth and biological ancestry, this paper argues that the generative model for the production or origin of the categories is in fact that of parthenogenesis, and that this is the only generative model that could have secured the epistemic status and legitimacy of the categories in the Critique of Pure Reason for Kant. This argument also reveals the gendered imaginary subtending Kant’s transcendental idealism and allows us to consider the implications of the parthenogenic model for Kant’s transcendental idealism in this light. (shrink)

What makes something an embryo—as opposed to what is actually, and not just in biotech parlance, a collection of cells? This question has come to the fore in recent years with proposals for producing embryonic stem cells for research. While some of those opposed to use of standard embryonic stem cells emphasise that adult cells have a clinical track record, others argue that there may be further benefits obtainable from cells very like those of embryos, provided such cells can be (...) derived in new ways. Rather than deriving them in ways that kill or otherwise endanger a living human embryo, they could be obtained from an entity that merely resembles a human embryo sufficiently closely for its cells to be of use. Such an entity might be created after introducing genetic changes to an ovum before it is activated by, for example, a cloning-type procedure, such that a gene essential to embryogenesis will be either absent, blocked in its expression, or overexpressed.1,2 The claim is that the ovum could be made to give rise to embryonic stem cells—mere living parts—without ever giving rise to a whole embryo, who is killed to obtain them. Whereas cloning “proper” winds back the specialisation of the cell nucleus to a point where a whole embryo is formed who has not yet specialised its cells, oocyte-assisted reprogramming , it is claimed, would wind back the specialisation merely to an intermediate point at which no embryo is created. Other methods proposed for deriving pseudoembryonic cells include parthenogenesis, in which an ovum is activated without a sperm, or even the insertion of an adult cell nucleus.1MORAL STATUS OF THE EMBRYOIn this paper, I assume that a genuine …. (shrink)

This essay considers biotrophic cyst and root‐knot nematodes in relation to their biology, host–parasite interactions and molecular genetics. These nematodes have to face the biological consequences of the physical constraints imposed by the soil environment in which they live while their hosts inhabit both above and below ground environments. The two groups of nematodes appear to have adopted radically different solutions to these problems with the result that one group is a host specialist and reproduces sexually while the other has (...) an enormous host range and reproduces by mitotic parthenogenesis. We consider what is known about the modes of parasitism used by these nematodes and how it relates to their host range, including the surprising finding that parasitism genes in both nematode groups have been recruited from bacteria. The nuclear and mitochondrial genomes of these two nematode groups are very different and we consider how these findings relate to the biology of the organisms. BioEssays 30:249–259, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Dignitas personae teaches that before research into certain alternative techniques for deriving human pluripotent stem cells can be licit, it is necessary to have moral certitude that no human embryo is brought into existence by those techniques. This article evaluates three such techniques—human parthenogenesis, ANT-OAR, and direct cellular reprogramming—and asks whether at present such moral certitude is achievable. National Catholic Bioethics Quarterly 10.1 (Spring 2010): 123–142.

In lieu of an abstract, here is a brief excerpt of the content:The Medusa Complex:Matricide and the Fantasy of CastrationJessica Elbert MayockThe theoretical structures of psychoanalysis have excluded the female subject by placing her outside of the Symbolic, and feminist theorists' responses to this problem have been divided. Some theorists (such as Kristeva) accept the notion of an unalterable Lacanian Symbolic, while others (such as Irigaray) maintain that the current Symbolic is a manifestation of male fantasy, and suggest that feminist (...) thinkers explore the possibility of reorganizing the Symbolic. Amber Jacobs, in her recent work On Matricide (2007), takes up this challenge by analyzing matricide in myth in order to reveal matricide as latent content untheorized within psychoanalysis. Jacobs claims that the structure of the Lacanian Symbolic illegitimately asserts the "law of the father" as the only possible law, excluding any possibility of a "law of the mother" by erasing the maternal role in theory and symbolization. Her project, following Irigaray, is to make visible those unconscious contents excluded by the patriarchal imaginary in order to "be able to intervene into psychoanalysis for the purpose of working toward theorization of unconscious structures that are not reducible to the structure of Oedipus alone" (Jacobs 2007, x). If Jacobs's suggestion is correct, then analysis of Freud's evidence for the Oedipus Complex (and its accompanying concepts) will reveal repressed contents and traces of these untheorized unconscious structures—particularly those associated with the maternal body.With these considerations in mind, I take up the Freudian case of Little Hans, where Freud finds his most seminal evidence for castration anxiety [End Page 158] and the Oedipus Complex. I will demonstrate Freud's systematic occlusion of the maternal body through his overvaluation of the male body/the phallus in order to expose the elements of male fantasy that construct the Oedipus Complex. I organize these psychical elements in a configuration called "The Medusa Complex," since Freud uses the image of Medusa to explain his theory of castration. In rereading the details of this case, a powerful male fantasy begins to emerge: the desire to appropriate the female generative power. This is achieved through the theory of castration, which the decapitation of Medusa symbolizes, and the unconscious wish for male parthenogenesis—one product of this wish is the Lacanian Symbolic structure, where only the male principle of the phallus is generative. The Medusa Complex is comprised of the two intertwined male fantasies of female castration and male parthenogenesis, as well as the associated resistances that result from initiation into this paradigm. The theory of castration and the Oedipus Complex are attempts to conceal the powerful maternal body and assert male superiority and dominance.In the case of Little Hans, "Analysis of a Phobia in a Five Year Old Boy" (1909), Little Hans develops a fear of horses (especially biting horses) and is afraid to go out into the street. Hans's treatment is undertaken by his father, a medical doctor, who keeps careful notes and acts under Freud's supervision (mostly via letters). The boy's phobia begins around the time his little sister Hanna is born, as Freud and the father eventually admit, though her role in their narrative is nonexistent.1 They interpret Hans's phobia as a classic Oedipal triangle in which he desires his mother and fears the hostility of his father; his fear is translated into fear of the castrating father. Throughout the case, Freud and the father emphasize the boy's alleged awe of the adult male genital organ. In this paper, I will revisit the case (preserved in careful detail by the boy's father) and systematically return the maternal body to its rightful place within the narrative, shifting both the structure and the meaning of the phobia.I am here reading the case as an example of manifest content—like the surface content of a dream—in order to expose the male desires that create it. The current Symbolic is essentially a dream of the male imaginary, and my method is to reveal the latent content of the dream, especially the fantasies that inform it. Desire is the generating force behind this dream, and until we encounter and understand this desire, it will continue to compulsively... (shrink)

In 1996 Congress passed the Dickey–Wicker Amendment as part of an appropriations bill; it has been renewed every year since. The DWA bans federal funding for research using embryos and parthenotes. In this paper, we call for a public discussion on parthenote research and a questioning of its inclusion in the DWA. We begin by explaining what parthenotes are and why they are useful for research on reproduction, cancer, and stem cells. We then argue that the scientific difference between embryos (...) and parthenotes translates into ethical differences, and claim that research on parthenotes is much less ethically problematic. Finally, we contextualize the original passage of the DWA to provide an explanation for why the two were possibly conflated in this law. We conclude by calling for a public discussion on reconsidering the DWA in its entirety, starting with the removal of parthenogenesis from this prohibition of National Institutes of Health funding. (shrink)

Despite the therapeutic potential of human embryonic stem (HES) cells, many people believe that HES cell research should be banned. The reason is that the present method of extracting HES cells involves the destruction of the embryo, which for many is the beginning of a person. This paper examines a number of compromise solutions such as parthenogenesis, the use of defective embryos, genetically creating a "pseudo embryo" that can never form a placenta, and determining embryo death, and argues that (...) none of these proposals are likely to satisfy embryoists, that is, those who regard the embryo as a person. This paper then proposes a method of extracting HES cells, what might be called the Blastocyst Transfer Method, that meets the ethical requirements of embryoists, and it considers some possible concerns regarding this method. It concludes by encouraging future HES cell research to investigate this method. (shrink)

The timeline of the Anthropocene – a geological epoch that Paul Crutzen and Eugene Stoermer say began in the late 18th century with the invention of the steam engine – seems like a brief and inconsequential blip, against the time scales embodied by the microbial communities. Wolbachia bacteria predate Anthropos by some 150 million years, and will likely outlast us. Wolbachia bacteria are worthy of their own geological epoch because they offer a fresh vantage point on one of the most (...) pressing ethical questions of our time: ‘How should we love in a time of extinction?’ Narratives about the Wolbachiacene have the potential to disrupt the overwhelming stories of tragedy orbiting around Anthropos, with disquieting and generative accounts of interspecies romance. Wolbachia often perform queer tricks inside their invertebrate hosts. In some host species these bacteria induce parthenogenesis – completely eliminating males from the population. Wolbachia can also transform genetic males into reproductively viable females. (shrink)

Don Marquis' future‐like‐ours account is regarded as the best secular anti‐abortion position because he frames abortion as a wrongful killing via deprivation of a valuable future. Marquis objects to the reductio ad absurdum of contraception as being immoral because it is too difficult to identify an individual that is deprived of a future. To demonstrate why Marquis’ treatment of the contraception reductio is flawed by his own future‐like‐ours line of reasoning, I offer an argument for why there is indeed a (...) candidate for harm—the ovum—for it can be viewed as providing the functional foundation for a new life through (1) mitochondrial DNA inheritance, (2) paternal histone restructuring during fertilization, and (3) ability to initiate parthenogenesis. As evidenced by these distinct and natural features of ova, candidate (2) “some ovum or other” should be morally prioritized as the direct candidate for harm in the contraception reductio. By assessing the philosophical inconsistencies in Marquis’ future‐like‐ours argument, this paper provides strong metaphysical grounds for rejecting the best secular anti‐abortion position. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Kennedy Institute of Ethics Journal 12.3 (2002) 305-323 [Access article in PDF] Scope Note 41 Bioethics and Cloning, Part I Susan Cartier Poland and Laura Jane Bishop This is Part One of a two part Scope Note on Bioethics and Cloning. Part Two will be published in the December 2002 issue of the Kennedy Institute of Ethics Journal and as a separate reprint. Contents For Parts 1 And 2 (...) Part 1Part 2I.History of the ScienceI.Ethical PerspectivesII.Historical CommentaryII.Religious PerspectivesIII.Animal WelfareIII.Fiction and FilmIV.Laws and Legal Literature"Clone" is a collective noun (I, Stewart 1997, p. 771). A collective noun names a group and is composed of individual members, such as "herd" or "flock." Derived from the Greek kl¯on for twig or slip, "clone" was first used in biology to describe the aggregate of asexually produced progeny of an individual, either naturally occurring or man-made; the definition later expanded to mean a group of genetically identical members who originate from a single ancestor. Thus, a clone is a group that results from the process of asexual reproduction.In nature, cloning occurs either by parthenogenesis (reproduction without fertilization) or by fission (embryo splitting). In a pioneering experiment in 1952, Robert Briggs and Thomas J. King (I, 1952), cancer researchers at the Institute for Cancer Research (today part of the Fox Chase Cancer Center) in Philadelphia, demonstrated on frogs another method of cloning by transplanting nuclei into enucleated cells, a technique called "nuclear transplantation," which John B. Gurdon and colleagues (I, 1958, 1975) used to create clones of frogs.Then, in the late 1970s and early 1980s, two back-to-back frauds in cloning occurred. First, the cloning of a human described by American science journalist David Rorvik in the 1978 book In His Image was called a hoax by a court in [End Page 305] 1982. Second, the cloning of three mice, announced by German wunderkind Karl Illmensee to scientific circles in 1979 (and to the public in 1981), could not be proven to be true, according to convincing evidence by McGrath and Solter (I) published in 1984.With their pronouncement that mammalian cloning was impossible, McGrath and Solter essentially stopped cloning research and funding for such biological research. So by the mid-1980s, instead of further investigating cloning, developmental biologists studied embryology related to in vitro fertilization, while molecular biologists studied recombinant DNA under the newly relaxed NIH guidelines. These two strands of scientific investigation came together in the work of Ian Wilmut, who created in vitro embryos using nuclear transplantation to reproduce genetically engineered cattle. Wilmut was seeking a way to increase the successful birth rate when, in the 1990s, he produced identical twin sheep, Megan and Morag, cloned from an embryonic cell, followed by another sheep, Dolly, cloned from an adult cell. The birth of a mammal from an embryo whose genetic material came from an adult cell firmly re-established the possibility of cloning from adults. Prior to Dolly's birth, scientists believed that adult cells lost the ability to dedifferentiate—i.e., to become unspecialized—and so could not direct the development of an embryo through to birth.The 1997 announcement of Dolly's birth initiated the present widespread discussion of cloning. Because of its potentially vast applications across human health, medicine, agriculture, and business/economics, cloning raises a host of issues including those concerning: genetics and genetic engineering, patenting, animal rights and/or animal welfare (especially for transgenic, research, or cloned animals), organ transplantation, reproduction, eugenics, pharmacology (drug production using transgenic animals), research practices, informed consent, stem cell research, women's rights, children's rights, parental rights and responsibilities, and theology and philosophy. It fosters questions about the meaning and purpose of life, the limits of human powers to intervene in research and therapy, and what it means to be human or animal. In addition, environmentalists and organic farmers raise concerns about the effect of novel animals and plants on the environment, while nutritionists and the lay public wonder... (shrink)

Sexual reproduction is almost ubiquitous among multicellular organisms even though it entails severe fitness costs. To resolve this apparent paradox, an extensive body of research has been devoted to identifying the selective advantages of recombination that counteract these costs. Yet, how easy is it to make the transition to asexual reproduction once sexual reproduction has been established for a long time? The present review approaches this question by considering factors that impede the evolution of parthenogenesis in animals. Most importantly, (...) eggs need a diploid chromosome set in most species in order to develop normally. Next, eggs may need to be activated by sperm, and sperm may also contribute centrioles and other paternal factors to the zygote. Depending on how diploidy is achieved mechanistically, further problems may arise in offspring that stem from ‘inbreeding depression’ or inappropriate sex determination systems. Finally, genomic imprinting is another well-known barrier to the evolution of asexuality in mammals. Studies on species with occasional, deficient parthenogenesis indicate that the relative importance of these constraints may vary widely. The intimate evolutionary relations between haplodiploidy and parthenogenesis as well as implications for the clade selection hypothesis of the maintenance of sexual reproduction are also discussed. (shrink)

The male gametes of most organisms lack cytoplasm. Consequently, most cytoplasmic genetic elements are maternally inherited: they cannot be transmitted patrilinnearly. The evolutionary interests of cytoplasmic elements therefore lie in transmission through the female. These elements may thus be in evolutionary conflict with nuclear genes which are transmitted by both sexes. This conflict is manifested in observations of cytoplasmically induced biased sex‐ratios. Some cytoplasmic genes avoid this fate by biasing the primary sex ratio towards females, or by inducing parthenogenesis. (...) Others kill male hosts, and either achieve transmission via dispersal, or benefit their clonal relatives in the dead male's female siblings. Still others cause the failure of zygotes resulting from pairings between males carrying specific microbes and females lacking them, causing an increase in the microbes through the sterilisation of non‐bearing females. Many, but not all, of these ‘ultra‐selfish’ microbes are closely related. Investigations of the significance of their phylogenetic affinities, or lack of them, their adaptability in terms of the methods by which they avoid, or ameliorate, the adverse effects of being in male hosts, and their importance as selective agents in the evolution of invertebrate sex determination systems, provide fertile spheres for future research. (shrink)

The author argues that an action is morally wrong if any of its steps serves no purpose apart from preventing the existence of a human being. This principle entails that contraception and some proposed techniques for altered nuclear transfer are morally wrong, but it does not preclude producing stem cells through parthenogenesis. His argument depends on the premise that human life always is a good, including human life produced through immoral actions. The immoral action, not the life caused by (...) the action, is the evil that should be prevented. National Catholic Bioethics Quarterly 10.2 : 257–264. (shrink)

Despite the therapeutic potential of human embryonic stem cells, many people believe that HES cell research should be banned. The reason is that the present method of extracting HES cells involves the destruction of the embryo, which for many is the beginning of a person. This paper examines a number of compromise solutions such as parthenogenesis, the use of defective embryos, genetically creating a “pseudo embryo” that can never form a placenta, and determining embryo death, and argues that none (...) of these proposals are likely to satisfy embryoists, that is, those who regard the embryo as a person. This paper then proposes a method of extracting HES cells, what might be called the Blastocyst Transfer Method, that meets the ethical requirements of embryoists, and it considers some possible concerns regarding this method. It concludes by encouraging future HES cell research to investigate this method. (shrink)

We use genomic information to tell us stories of evolutionary origins. But what does it mean when different genomes report wildly different accounts of lineage history? This genomic “discordance” can be a consequence of a fascinating suite of natural history and evolutionary phenomena, from the different inheritance mechanisms of nuclear versus cytoplasmic (mitochondrial and plastid) genomes to hybridization and introgression to horizontal transfer. Here, we explore how we can use these distinct genomic stories to provide new insights into the maintenance (...) of sexual reproduction, one of the most important unanswered questions in biology. We focus on the strikingly distinct nuclear versus mitochondrial versions of the story surrounding the origin and maintenance of asexual lineages in Potamopyrgus antipodarum, a New Zealand freshwater snail. While key questions remain unresolved, these data inspire multiple testable hypotheses that can be powerfully applied across a broad range of taxa toward a deeper understanding of the causes and consequences of mitonuclear discordance, the maintenance of sex, and the origin of new asexual lineages. (shrink)

Bioethics, Volume 35, Issue 7, Page 680-687, September 2021.

This paper looks at the role nonhuman animals play in how we think about sex, gender, and sexuality in zoology and in society. In examining the history of ideas regarding a microscopic invertebrate species—rotifers—the paper explores how humans have projected aspects of their lives onto nonhuman animals and how they have extrapolated from nonhuman animals to human society. The paper emphasizes the intersections between knowledge about nonhuman animals and gender and sexuality politics.

The unusual occurrence and developmental diversity of asexual eukaryotes remain a puzzle. De novo formation of a functioning asexual genome requires a unique assembly of sets of genes or gene states to disrupt cellular mechanisms of meiosis and gametogenesis, and to affect discrete components of sexuality and produce clonal or hemiclonal offspring. We highlight two usually overlooked but essential conditions to understand the molecular nature of clonal organisms, that is, a nonrecombinant genomic assemblage retaining modifiers of the sexual program, and (...) a complementation between altered reproductive components. These subtle conditions are the basis for physiologically viable and genetically balanced transitions between generations. Genomic and developmental evidence from asexual animals and plants indicates the lack of complementation of molecular changes in the sexual reproductive program is likely the main cause of asexuals' rarity, and can provide an explanatory frame for the developmental diversity and lability of developmental patterns in some asexuals as well as for the discordant time to extinction estimations. (shrink)

Here, I propose a new hypothesis: sex originated from an archaic gene transfer process among prebiotic bubbles without the prerequisite for reproduction. This de‐coupling from reproduction might make the thorny problem of accounting for the evolution of sex, despite the apparent advantages of parthenogenicity, more tractable.

The German–American physiologist Jacques Loeb (1859–1924) and the Polish embryologist Emil Godlewski, jr. (1875–1944) contributed many valuable works to the body of developmental biology. Jacques Loeb was world famous at the beginning of the twentieth century for his development and demonstration of artificial parthenogenesis in 1899 and his experiments on regeneration. He served as a role model for the younger Polish experimenter Emil Godlewski, who began his career as a researcher like Loeb at the Zoological Station in Naples. Following (...) Godlewski’s first visit to Naples in 1901 a close relationship between the two scientists developed. Until Loeb’s death in 1924 the two exchanged ideas via correspondence that was only interrupted during the First World War. The aim of the paper is to examine the transatlantic transfer of knowledge in the field of biological experimentation that was fostered by these two protagonists. Using a modification of Bruno Latour’s model of the ‘Circulatory System of Science’ as a heuristic tool, different mechanisms of scientific exchange are displayed. With the help of Loeb’s and Godlewski’s correspondence the role of scientific communities, methods, allies, the public and institutions in the process of knowledge transfer are analysed. Preconditions for success and failure in transferring science are examined. (shrink)