The politics of care in technoscience.

Care is a slippery word. Any attempt to define it will be exceeded by its multivocality in everyday and scholarly use. In its enactment, care is both necessary to the fabric of biological and social existence and notorious for the problems that it raises when it is defined, legislated, measured, and evaluated. What care looks and feels like is both context-specific and perspective-dependent. Yet, this elusiveness does not mean that it lacks importance. In our engagements with the worlds that we study, construct, and inhabit, we cannot but care: care is an essential part of being a researcher and a citizen. To properly invite you into this Special Issue, then, we need to say something about what we mean when we write about care.

Ray Owen and the history of naturally acquired chimerism.

This article interweaves a history of Ray Owen's early work with a broader account of the conceptual landscape of immunology in the mid 1950's. In particular, Owen's openness to the very possibility of chimeric phenomena is recognized.

'Something there is that doesn't love a wall': histories of the placental barrier.

This article appraises the late twentieth century maxim that prior to thalidomide's clarion call in 1961, a generic "we" believed that the fetus was protected from external insult by the placental barrier. Complicating this truism, we demonstrate that the placenta was, since early in the twentieth century, conceived of as a site of constant passage of entities both necessary to, and dangerous for, fetal development. Moving between evidence from specialist journals, obstetrics textbooks, and pregnancy advice manuals, we argue that the placental barrier writ large only emerged as an explicit actor after the medical community was disillusioned with it: it became something that does not exist. The article proposes that the nostalgia for a barrier lost constructs the modern-day fetus as more exposed and vulnerable than if "we" had never imagined this protection in the first place. The rhetorical shorthand of the erstwhile placental barrier has both deflected more nuanced accounts of the thalidomide story and contributed to the increasing surveillance of pregnant women's behavior, particularly in late twentieth century North America.

'Incongruous juxtapositions': the chimaera and Mrs McK.

A century ago, the German botanist Hans Winkler (best known for coining the term 'genome') accomplished two novel transplantations. First, he produced a single plant that grafted together two completely disparate species: tomato and nightshade. Second, he chose the descriptive word 'chimaera' to name his innovation, transplanting the term from mythology to biology. This paper features Mrs McK, the first human chimera, and thus follows the term from botany to clinical medicine. Her remarkable story, pieced together from the notes, drafts and correspondence of Robert Race and his colleagues at the MRC Blood Group Unit, draws attention to the significance of names and naming.

The chimera of liberal individualism: how cells became selves in human clinical genetics.

Using Ian Hacking's notion of "making up people", this paper argues that human chimeras--people who contain more than one genetically distinct cell population--have been made up. As with multiple personality, the discourse surrounding the phenomenon of chimerism offers a novel vantage point for examining the socio-political processes of subject formation. Evidence from archives, interviews with cell scientists, and popular sources will show that, in a strange leap that has come to seem self-evident, journalists, laypeople, and even scientists have come to equate genomes with selves and hence conclude that chimeras are more than one person. Thus far, the challenge that chimeras pose to the simple alignment of genome-body-person has been limited both by relegating chimeras to freak show status and by liberal institutions' demands that individuals be singular.