Zoomorphizing the Human: How to Use Darwin's Coral and Barnacles
Ming Chuan University, Taiwan
A man ... is really no more a person, one and indivisible, than is the coral with its million polypes [or] the tree with its million buds. – Charles Kingsley, 'I'
Figure 1: Early tree of life diagram. (Barrett et al. 177)
 One of Darwin's principal preoccupations in the "B" notebook (1837-8) is the search for a metaphor or image that adequately captures the complex differentiation of organisms from their origin to the present. With tentative formulations and abstract sketches he considers several possibilities, including a "tree of life" with "triple branching" to represent the three elements of air, land, and water, as well as a forerunner (see fig. 1) of the well-known tree of life diagram presented in On the Origin of Species. Between these two trees, however, he proposes a different metaphor: "The tree of life should perhaps be called the coral of life, base of branches dead; so that passages cannot be seen – this again offers contradiction to constant succession of germs in progress." At a later date he adds, "no [...this] only makes it excessively complicated" (Barrett et al. 177; see fig. 2). If the characteristics of coral seem more attuned to Darwin's conceptions of time and life, why did he abandon the "coral of life" in favor of the tree? Leaving aside the rhetorical force the latter gains from its biblical resonance, the answer appears in his description of coral, which obscures its past "passages" and "excessively complicate[s]" continuity, linearity, and "progress." In other words, coral's structure resists narrativity and defies the visual simplicity required by diagrams – hardly a good choice for a naturalist so concerned with lucidity. Despite his ultimate decision, however, careful attention to Darwin's early writings on coral – and another marine species, barnacles – reveals how such organisms played a crucial symbolic role in deconstructing dominant conceptions of subjectivity, gender, and time. In addition, a focus on the biological characteristics of these organisms provokes an interesting philosophical meditation on the nature, limits, and political value of both epistemology and ontology.
Figure 2: Coral of life diagrams. (Barrett et al. 177)
 The complex nature of coral – its reticulations, interpenetrations, opacity – made it a problematic organism for mainstream Victorian science, which tried to ground itself in the discrete and perceptible, in taxonomy and nomenclature, empirical facts and statistical data. Indeed, coral's resistance to clear visual and linguistic articulation nicely represents the taxonomic meltdown that began to occur in the middle of the nineteenth century.  Coral, barnacles, and other marine invertebrates posed a series of classification problems in relation to anatomy, especially sex, during the 1830s and 1840s.  In this sense coral marks an ambivalent moment in Darwin's career: on the one hand, its subversion of fixity nicely dovetails with his evolutionary beliefs; on the other, it presents an obstacle to representing those beliefs on the page. As Darwin frequently acknowledges in his notebooks, life's full history eludes representation. To reduce life to language and images leaves something out. In the "C" notebook (1838), for instance, he remarks that there "is [the] same difficulty in arranging animals in paper as drying [a] plant[:] all [is] brought [together] in one plane" (286). To "arrange" life, to bring it within the grasp of epistemology, one must paradoxically destroy that which is living in it – like a pressed plant, one must collapse its multiple textures into one plane. A true diagram of life, if such a thing were possible, preserves life's dynamism, its interpenetrating three- or four-dimensionality, along with the virtual layers of the past (the coral's dead "base of branches") invisible to the limited perspective of the present. Such a diagram could be a tree of life "erect not pressed on paper, to study the corresponding points" ("D" notebook 352). Or, as Darwin suggests in the "B" notebook, one could shift metaphors entirely, from the arborescent to the coralline: the "coral of life."
 But what are the characteristics of the coral of life and, more importantly, what are the benefits of thinking through these characteristics and this metaphorical shift? The Voyage of the Beagle (1839) provides a description of coral – written and published contemporaneously with the notebooks – that suggests some answers. Using epic language, Darwin depicts how "low, insignificant coral islets stand and are victorious" against the relentless erosive force of waves:
The organic forces separate the atoms of carbonate of lime one by one from the foaming breakers, and unite them into a symmetrical structure. Let the hurricane tear up its thousand huge fragments; yet what will this tell against the accumulated labour of myriads of architects at work night and day, month after month. Thus do we see the soft and gelatinous body of a polypus, through the agency of the vital laws, conquering the great mechanical power of the waves of an ocean, which neither the art of man, nor the inanimate works of nature could successfully resist. (485)
Ironically, the same characteristics that make coral difficult to represent also make it an apt metaphor for life itself. Coral reefs, and by extension all organic life, emerge as the accumulated result of millions of imperceptible, creative forces. The microscopic, accretive "labour" of polypi operates beneath human perception yet rises above "the art of man," just as the productions of natural selection exceed those of domestic selection. Despite – or because of – its "soft and gelatinous body," coral overcomes "mechanical" matter, making the plasticity of the body integral to the productive potential of life. Moreover, each polypus cannot be isolated from other polypi and the overall coral islet; this other, collective body is an architectural "structure," an aesthetic production. These dynamic, interpenetrating qualities defy arrest in diagrammatic form. Thus, the coral of life is more amenable to the flux of time than the fixture of space – more appropriate for a theory of evolution than a natural theology or even a natural history.
 The coral of life is therefore both a metaphorical abstraction and a real assemblage of organic components. It had, and has, several important implications. First, metaphors and diagrams representing evolutionary differentiation played a vital role in Darwin's reconception of time and ontology. In particular, (what became) the tree of life is full of what Gillian Beer describes as "mythic potentiality" because, as an overdetermined image, "it could as well be interpreted by the eye as shrub, branching coral, or seaweed" (86). Regardless of which species it is taken to resemble, the tree of life reconceives temporality by conjoining time's flux with the development of organisms. As Beer puts it, Darwin "needed a metaphor in which degree gives way to change and potential, and in which form changes through time." Darwin selected the tree of life because it was "substantial, a condensation of real events, rather than a metaphor" (33). In other words, the tree of life as quasi-metaphor conveys real change – change in kind rather than degree – that binds time to the accumulated actions and deformations of organisms. This conception of time and life as a continuum is, as Darwin recognizes in his notebooks, a rather messy affair. As a complex and interconnected tissue of differentiations, it is more rhizomatic than arborescent,  more like a coral of life than a tree of life, and therefore yields less to scientific representation than the famous tree of life diagram would suggest. In many ways the coral of life more adequately articulates (through its reticulations and opacity) the vicissitudes of evolution. Consider natural theology, which makes the history and identity of all animals, including humans, the effects of divine intervention. Under this vertical model, organisms are the discrete creations of an ongoing dialectic between time and eternity. The coral of life offers a radical alternative: what Darwin calls, in the "B" notebook, a "horizontal history" of organic development (227). 
 Moreover, by conjoining time and ontology in the coral of life, Darwin implies a different modality of human subjectivity. In the wake of his evolutionary theory, Victorian science and literature modified "the human" by exploring various ontological attachments to non-human organisms: human as vampire (Le Fanu; Stoker), beetle (Marsh), monkey (Haggard; Huxley; Le Fanu), etc. Darwin's insistence on the complex interconnectedness of all life appends a series of real and metaphorical links to human subjectivity that tear the human apart. Recast as coral, subjectivity can no longer be understood as discrete and eternal; rather, it is multiple and ramified. It emerges as a result of imperceptible forces that unfold through time and through bodies. These qualities make coral a fascinating "model organism" for human (or post-human, non-human) subjectivity. As Mary Poovey describes them, "model organisms" are knowledge-organizing metaphors that cut across biology and literary criticism, gradually becoming reified as they are invoked by these disciplines. The entire project of literary criticism, she claims, is organized around an assumed, and borrowed, metaphor – the "organic whole" of Romantic biology – when what we need in order to diversify our knowledges are "different metaphors [put] to a different use" (438). Like the rhizome in Nancy Armstrong's investigation of fin-de-siècle subjectivities,  coral offers a powerful organic metaphor for describing subjects that further extends, or deforms, our understanding of how they were produced in the nineteenth century. Coral led a promiscuous cultural life outside the bounds of Darwin's notebooks, appearing in several scientific and literary works, often alongside barnacles and other closely related marine life. Indeed, because it straddles the organic and inorganic and constitutes a series of connections between individual polyps, limestone, barnacles, fish, and other marine life, coral lends itself to metaphorical proliferation.
 Coral and barnacles as model organisms bring into question what it means to be human: coral challenges human identity and historical narratives; barnacles' diffuse sexual anatomy undermines binary conceptions of human gender. Coral and barnacles infest and alter the human. While it is true that many descriptions of animals were and continue to be anthropomorphic, this form of distortion works both ways. Barnacles can be humanized, but humans will acquire cirripedean qualities in the process. For instance, readers of Darwin's letters are introduced to Mr. Arthrobalanus (his name for a favorite barnacle specimen), but he exists alongside Little Dorrit's Barnacle family and Olive Schreiner's Jonathan Barnacle, a character in Undine. John R. Durant argues that this metaphorical interplay between human and non-human is a distinctly Darwinian strategy whereby "anthropomorphic zoology combine[s] with zoomorphic anthropology in effecting the unification of animals and man" (292). Darwin's goal of breaking down the barrier between animal and human was partially achieved through such metaphorical translations. Thus, by investigating the ontological limits of coral and barnacles, Victorian science and literature collapsed traditional oppositions and (r)evolutionized human subjectivity.
 In the remainder of this essay I will emphasize an opposition crucial to analyses of subjectivity, one that Darwin's barnacles undermine and recast: the masculine/feminine gender binary. Here I attempt to elaborate on Elizabeth Grosz's argument, in The Nick of Time (2004) and Time Travels (2005), that a renewed struggle with the philosophical and political implications of Darwin's writings is key to placing feminist theory into productive collision with discourses it has tended to reject, especially the natural sciences. For Grosz, what makes Darwinian evolution exciting is its unrelenting openness to the future, which precludes biological – including sexual – determinism. Indeed, Darwin's iconoclastic account of barnacle sex makes sexual difference (male/female) one of the primary generative – and destabilizing – forces behind evolution. (Even in his Monograph on barnacles, published in 1851 and 1854, he subtly but strongly builds the case for evolution.) His description of barnacle sex therefore provides a potent, though implicit, challenge to Victorian gender arrangements, which were assumed to be eternally prescribed. As we attend to the unique qualities of barnacle sex, a theory of sexual evolution emerges that differs in important ways from the sexual selection of The Descent of Man. Rather than focusing on masculine aggression and feminine choice, the Monograph multiplies sexual categories and gestures toward the process of differentiation that produced them. Ultimately, by examining Darwin's non-canonical writings, we gain a fresh perspective on evolutionary theory and its productive relation to feminism and subjectivity.
 In the following section I examine Darwin's two-volume A Monograph on the Sub-Class Cirripedia with Figures of All the Species, his first sustained, albeit implicit, treatise supporting evolution. I claim that the text performs the following operations: it simultaneously exemplifies the shift to a new, "horizontal" history and problematizes the notion of linear progress; it demarcates the ontological limits of epistemology and language; and it reconceptualizes subjectivity by scrambling the traditional spatial topography of the body, defining the "individual" as a parasitic interpenetration, and replacing the masculine/feminine binary with a developmental account of sexual difference.
Darwin's Barnacles: A "Marvellous Assemblage of Beings"
 In his Monograph, Darwin innocuously employs familiar scientific methods to probe the limits of knowledge and, inadvertently perhaps, human subjectivity. The text largely consists of the dry tabulation of empirical details on the bodies and habits of barnacles. By exhaustively explicating one species, Darwin hoped to hone his skills in close anatomical analysis and, more significantly, provide an authoritative basis for his projected advocacy of transmutation – thus avoiding the kind of general disdain heaped on Vestiges by T. H. Huxley and other scientific luminaries.  Indeed, we can read the Monograph as Darwin's first, guarded attempt to lay the groundwork for a theory of evolution. As Janet Browne suggests, the Monograph's "taxonomic arrangement was steeped in ideas derived from his theory of evolution" (504), and this evolutionary frame expands the effect of the details. Attention to the form of the volumes reveals some salient contours of their content. The Monograph is divided into two volumes, the first devoted to pedunculated (stalked) and the second to sessile (fixed) barnacles, although the pedunculated family reemerges at the end of the second volume.  This reemergence signifies their crucial symbolic role, for this family includes those species that exhibit sexual differentiation: those with hermaphrodites and "complemental males," and those with distinct females and males. All other barnacles are hermaphrodites. When one considers that the "idea of an aboriginal hermaphrodite stood at the heart of his theories" (Browne 478), it becomes clear why sexually differentiated barnacles formally dominate the treatise. Alcippe, Cryptophialus, Ibla, Proteolepas, and Scalpellum, the five genera with "singular sexual relations" (1:vi), account for one-fifth of the pages in both volumes of the Monograph, despite the fact that these genera represent only about seven percent of all barnacle species. The incidence of exclamation marks is also far higher in these sections, punctuating the emphasis Darwin places on this "marvellous assemblage of beings . . . with scarcely anything in common, and yet all belonging to the same species!" (1:293). Such emphasis was not lost on contemporary readers. Jonathan Smith points out the literary response of Charles Dickens, whose Little Dorrit (1855-7) includes a satire on the sexually and bureaucratically corrupt Barnacle family (63-8). But where Dickens saw a menace, Darwin saw a theoretical linchpin.
 Darwin's first formulation of natural selection appears in 1838, in the "B" notebook. Thus, by the time he published the first volume of the Monograph, he had been convinced of evolution for at least thirteen years. We see the effect of this conviction in the many passages on intermediate forms, the productivity of extinction, and the nonteleological, plural temporalities evinced by the lives of barnacles. Foreshadowing the analogical argument of Origin, Darwin delicately suggests that "varieties may interbreed, and so produce numerous intermediate forms. Whether or not this could take place, I am inclined to look at these two species [B. tintinnabulum and B. amphitrite], as in an almost analogous condition with our domestic animals, which give rise to such infinitely numerous varieties" (2:197). In addition, such mutability dissolves the formal and taxonomic division between pedunculated and sessile barnacles, as evidenced by the Verrucidae family, a morphological intermediary between the two. Verrucidae is geologically intermediate as well, tying bodily change to the lapse of time (2:496, 512). Even individual organs occupy a liminal space and time, like the "curious" mandibles of Lepadidae, "to a certain limited extent, intermediate between" other articulated animals (1:40). These cautious forays into evolutionary territory cumulatively reinforce other strands of Darwin's theory. For instance, he claims that local pressures of destruction (what will come to be known as "natural selection") elicit the mutual adaptation of organisms. Tiny, parasitic "complemental males" cannot attain a normal size because "they would either be killed by the pressure of the scuta of the Scalpellum [the protective valve of the hermaphrodite host], or they would destroy the latter, and in doing so soon lose their own support, and thus necessarily perish!" (1:262-3). Darwin repeatedly hammers home this point and others, such as the relation between geographical isolation and variation, with exclamatory flourish: "decay or disintegration, and breakage, are necessary elements [of] growth!" (2:55). These vibrant passages punctuate a treatise largely written in a tone of objective detachment, indicating, at the moment of their irruption, "breakages" in the text's logical structure.
 Darwin also provides a complex account of temporality, one that further prepares the ground for the acceptance of evolution. Specifically, he attacks two conceptions of temporality, both of which were dominant at mid-century and both of which logically preclude evolution. The first is the assumption that eternity and God regularly intervene in time. This position was espoused by natural theologians like William Paley, whose creator-god designs organisms as so many intricate watches. The second, related temporality conceives of time as progressive and teleological – leading, in the end, toward eternal perfection – which assumes a linear sequence opposed to the unpredictable, nonhierarchical, and ramified process of evolution. Barnacles, especially larvae and sexually differentiated species, possess empirically demonstrable life stories that elude both temporalities, and Darwin is quick to exploit them. The narrative of larvae and their metamorphosis into adults reverses, even parodies, progressive development.  A larva swims freely, using its antennae for ambulation. As it matures, however, it drives its head into an adjacent surface and injects a cementing fluid through its antennae, living as an adult in a state of "involuntary and permanent" attachment (1:16). Sensory organs diminish; acoustic sacks disappear and eyes retrogress from compound to simple (1:21-2). Darwin's description of adult males further develops this atavistic narrative. Males are "in an embryonic condition, though unquestionably mature" (1:198), and these overlapping temporalities become strikingly embodied in Darwin's description of Scalpellum vulgare. The complemental males of this species attach themselves to the shell of the hermaphrodite, regularly emitting sperm to augment their host's "masculine efficiency" (1:182). Eventually, several males in various stages of development become "cemented together" in layers. In one case "the lowest one was white, pulpy, and recently attached; the two above . . . were mature; and the third still higher up, was dead, empty, transparent, and half decayed" (1:241). Embryonic and mature, their lives a macabre procession of mechanical sexuality and inverted burial, male barnacles exhibit a bizarre temporality utterly foreign to the Victorian narratives of progress and masculine superiority: "these singular creatures [are] destined to discharge their spermatozoa, die, and be succeeded by a fresh set of short-lived male successors" (2:586). The life stories or temporalities of barnacles retain no evidence of transcendent intervention. They display neither progression nor purpose. Instead, like the coral of life, they are staggered, discordant, layered, and plural.
 The complex, reticulated bodies and temporalities of barnacles strain the epistemological limits of natural history as it was structured before Darwin. The dynamic ontology proposed by evolution requires an equally mobile form of knowledge, thus Darwin makes the deficiencies of scientific discourse a crucial aspect of his theory. In On the Origin of Species, for instance, he demonstrates that classification is arbitrary; even the term "species" has an "undiscovered and undiscoverable essence" (456). Ironically – perhaps intentionally – the two-volume Monograph offers a mass of taxonomic distinctions and empirical detail, but it ultimately documents how barnacles evade definition. Darwin describes the crumbling barnacles kept in the British Museum, but these incomplete specimens signify the difficulty of fitting live barnacles into scientific discourse, especially when the sheer multiplicity of their monstrous, dubious forms provokes intellectual humility. Darwin apologizes for the "violence to the principles of classification followed throughout this work" (2:470), but he makes this a necessary violence, one subversive enough to bring his own scientific authority into question. At one point he meticulously records the process of classification, the "vacillations" and doubt he experienced while attempting to arrange the myriad varieties of Balanus tintinnabulum, insisting that "it has not been from indolence that I have combined so many forms" (2:197). Elsewhere he feels "almost ashamed" (2:310) to name a doubtful species. Such moments mark the recurring textual slide from sober facticity to intuitive understanding: "After considerable experience, when numerous varieties of a species have been carefully examined, the eye acquires a sort of instinctive knowledge, by which it can recognise the species, though the character cannot be defined by language" (2:155). Darwin suggests that the extreme variability of barnacles poses a serious problem to a natural history built upon fixed categories – indeed, it poses a problem to language itself. He uses the Monograph, then, to posit a different conception of life, one that attempts to explore and represent the malleability of bodies.
 In particular – borrowing the language of Thomas Kuhn's The Structure of Scientific Revolutions – the amorphous organs of barnacles presented an anomaly to three paradigmatic discourses that had become more and more precise (i.e., had reached the limits of "normal science") by the 1850s: a natural history based on the rigid distinctions of taxonomy; a human history made progressive and linear through its dialectic with eternity; and an anatomical science that grounded human identity in static, normalizing maps of the body. With barnacles, "character after character fails and blends away by insensible degrees" (2:242), and this dynamism erodes, or redistributes, previously commonsensical facts. Darwin's depiction of cementing ducts in Elminius kingii provides a good example. These ducts, which channel cementing fluid through the antennae to a chosen surface, are "as tortuous as the track of a worm. Each gland gives out two ducts, which bifurcate repeatedly, and often inosculate, making, in parts, an hexagonal mesh-work . . . . [S]o numerous are the ducts, that the basal membrane may be compared to pieces of paper with the fine fibrous branching roots of some plant dried and heaped on it" (2:146). In combination with the breathless final sentence, the stuttering clauses and alliterations of this passage advance its deconstructive content: Darwin implies that we can only hesitantly and obscurely trace the ramifications (in both senses) of the barnacle body. The simile of dried roots on paper recalls his attempt in the notebooks to visualize the history of life, and although the "C" notebook declares that there "is same difficulty in arranging animals in paper as drying plant, all brought in one plane" (Barrett et al. 286), the cementing ducts of barnacles offer additional diagrams of this history (see fig. 3).  Darwin presents an alternative conception of the body and time by splicing these zigzagging cementing ducts directly into sex and evolution:
Figure 3: Cementing apparatus/ovarian system of barnacle. Darwin, Monograph (2: plate 28)
I feel an entire conviction . . . that the cement-glands and ducts are continuous with and actually a part of an ovarian tube, in a modified condition; and that the cellular matter which, in one part, goes to the formation of ova or new beings, in the other and modified part, goes to the formation of the cementing tissue. To conclude with an hypothesis, – those naturalists who believe that all gaps in the chain of nature would be filled up, if the structure of every extinct and existing creature were known, will readily admit, that Cirripedes were once separated by scarcely sensible intervals from some other, now unknown, Crustaceans [with a simple ovarian-cementing apparatus]. (2:151-2)
From tortuous cementing ducts we move by "insensible degrees" to ovaries and the formation of "new beings" and "unknown" creatures. What were once distinct organs and organisms can no longer be differentiated. This blending of the body, both internally and in relation to other bodies through time, offers a powerful metaphorical alternative to the rigid "chain of nature," which is so subtly juxtaposed to the ramifications of barnacles.
 Darwin persistently scrambles the topography of the body in the Monograph, forcing the reader to imaginatively deform, or evolve, the animals under consideration – even to the extent of altering conceptions of the human. Barnacles' physical composition presents a series of disorienting facts: the regular molting of their interior membranes, such as the lining of the esophagus, rectum, and olfactory pouches (1:61-3); the eye that develops beneath the muscles of the male Scalpellum vulgare (1:235); the "suctorial mouth" and inverted mandibles of Proteolepas bivincta, which are "absolutely incapable of prehension" (2:591-3). Moreover, it becomes clear that these mutations emerge at the productive intersection of sexuality and sexual difference: in effect, Darwin accentuates the female characteristics of sexuality, which Elizabeth Grosz defines as "its fluidity, its contiguity with the nonsexual, its indeterminacy of organs and sensations, its tactility, formlessness, open-endedness" (Time Travels 213). As we have seen, the network of ovarian tubes that feather into the cementing apparatus erodes coherent distinctions of form and function. The testicular system in the genus Conchoderma likewise "run[s] into all the filamentary appendages," making it difficult, at times, to locate the extremities of sex. Paradoxically, barnacles that are discernibly female and male deviate most widely from the bodies familiar to most Victorians. From the interactions of the ovarian and testicular systems – a difference that remains irreducible in the Monograph – more and more somatic forms arise, some of them deserving of an exclamatory mark. For example, the female of Alcippe lampas has a mouth and an esophagus but no eyes, rectum, or anus, while the male has eyes but no mouth, stomach, rectum, or anus (2:546-7). When Darwin stretches the penis of Cryptophialus minutus between two needles, he finds "that this organ could be extended by the animal to . . . between eight and nine times its own entire length!" (2:586). As early as the mid-1840s, Darwin playfully brings such structural oddities into relation with the human, nicknaming a Cryptophialus with two penises "Mr. Arthrobalanus" (Browne 471). (In keeping with the inscrutability of barnacle sex, Darwin later realizes that the double penis is actually part of the cirri, and "Mr." Arthrobalanus becomes an "it," "with male and female parts separated out yet mutually interdependent" [Stott 218].) In the Monograph he makes the connection to the human more seriously but tortuously, tracing a path from branchial to bronchial to ovarian tubes and beyond: "the movement of [the branchial sack], indeed, may be almost compared to the heaving of a man's chest . . . . [I] can hardly doubt that the branchiæ in the Balanidæ [sessile barnacles] are the ovigerous fræna of the Lepadidæ [pedunculated barnacles] in a modified condition; a transformation of function not greater than that of the swimming bladder of a fish into the lungs of the higher Vertebrata" (2:63-5). The rhetorical methods of abutment, juxtaposition, and analogy, which parallel the contours of the barnacle body, result in an evolutionary net that entangles all organisms, including humans.
 Darwin continues to refigure identity by smudging the external boundaries of the body, pushing the interior networks of barnacles – especially their sexual organs – directly into the flesh of other organisms. Many barnacles are parasitic, attaching themselves to coral, marine mammals, fish, seaweed, other barnacles, and humans (ships) with their antennae, or what we might call their ovarian-cementing-ambulatory apparatus.  Because the "fine network" of cementing fluid "has the capacity of occupying and filling up all inequalities in the supporting surface . . . penetrating into, and even almost blending with the epidermis" (2:135), it becomes difficult to detach these couplings, to mark where one creature ends and another begins. The problem this poses for the acquisition of scientific knowledge metaphorically folds human subjectivity into the confusing spaces of barnacle morphology. An analysis of barnacles inevitably draws the analyst into a performative engagement with ontological diffusion. Thus, Darwin exclaims, naturalists may miss the real distinction between two organisms by becoming lost in the continuum between them: "the skin of the Whale has been mistaken by some authors for parts of the Cirripede!" (2:401). He suggests that a delicate balance must be maintained between two opposing tendencies: on the one hand, the continuity between species; on the other, the indefinable difference we perceive between, say, a whale and a barnacle. As we have seen, barnacles present many instances of the former. Their life stories imply a temporal narrative of interpenetration and evolution. Their bodies develop internal networks and external assemblages. But they also embody the latter. Sexual difference is the most important element in this regard because it forms the connections and produces the differences. Darwin implies that a complete genealogy of barnacle development – one dimly suggested by the fossilized barnacles at his disposal – would reveal a sexual continuum running from hermaphrodites to bi-, tri-, and poly-sexual species. But when he examines living barnacles, or barnacles that exist in the present, he finds separate sexual forms with no direct gradations. How and why did barnacles develop these separate sexes? Does sex play a role in its own development? How? To unravel these questions, and to uncover their implications for human subjectivity, we must examine in more detail the function performed by sexual difference.
 It is important to keep in mind that, for Darwin, sex is dynamic and diffuse, consistently eluding stasis and clear definition. Like plants, barnacles engage in collective reproduction, their sperm pollinating the ova of multiple individuals. This reproduction is not strictly heterosexual, for barnacles present a spectrum of sexed anatomies, with frequent cross- and (more rarely) self-fertilization occurring among hermaphrodites. Moreover, the text paradoxically makes sexually differentiated species the most entangled. Ibla cumingii displays the typical arrangement of such species: within the sack of the female we find the parasitic male, a "flattened, purplish, worm-like little body." The male's peduncle closely adheres to the inner textures of the female, "running along amidst the under-lying muscles and inosculating fibrous tissue[and] attached to them by cement at the extremity" (1:189-90). In some cases "the sexes cohere, but are essentially distinct." To explain this contradiction, Darwin uses Richard Owen's description of Syngamus trachealis, a parasitic worm: "the male is organically blended by its caudal extremity with the female, immediately anterior to the slit-shaped aperture of the vulva. By this union a kind of hermaphroditism is produced; but the male apparatus is furnished with its own peculiar nutrient system; and an individual animal is constituted distinct in every respect, save in its terminal confluence with the body of the female" (1:200-1). The female and male are not simply glued together but "organically blended," materially confluent and inseparable. An "individual animal" persists, however, "distinct in every respect." Darwin and Owen articulate a paradox that offers some significant implications. First, it defuses any charges of essentialism that may be directed at the Monograph's theory of sex and sexuality. There are no identities that exist long enough, or discretely enough, to have an essence – primarily because sex induces endless morphological change and interpenetration. Second, it forces us to take seriously the real, albeit indefinable, differences between the sexes. How were these biological differences understood in the Victorian period? Did they ever function to overcome, rather than reinforce, existing social arrangements between women and men? Can we use them in a similar fashion today?
 In the Monograph Darwin opens up these questions and suggests some tentative answers. He traces continuous series of sexual differences that mimic their evolutionary emergence in time. Along some of these series, at some indefinite point, males and females quite distinct from their hermaphroditic precursors – and distinct, as well, from mainstream Victorian gender roles - materialize. For example, Darwin describes parasitic males as not "really independent creatures [but] merely in a different state of sexual development" (1:285). He also asserts that "the male and female organs may be developed in inverse degrees in different and adjoining individuals" (1:180). Thus, sex is a fluid series of "states" or "degrees" that accompanies, or develops, the "different." Discernibly female and male organisms must extend beyond a certain threshold of difference. When they do, they exhibit remarkable qualities – and as usual, Darwin accentuates their significance with exclamation marks. While sexually differentiated species were doubtless of scientific interest to Darwin, they gain some of their startling force when viewed as he must have viewed them: from the perspective of Victorian phallocentrism. Darwin is surprised to find a "large distorted" female Alcippe lampas that "actually had twelve males, and two pupæ on the point of undergoing their final metamorphosis . . . attached on one side, and all evidently must have been alive together!" (2:556). It is unclear what elicits more surprise: that this female had fourteen "husbands" (Darwin's term in letters to Lyell), or that they were all alive in the shell together, a massive case of polyandry. Regardless, the Monograph consistently places females in a dominant position. They are more differentiated than the males: "The whole case seems to me very singular, and, as far as my knowledge extends, unique: we have two animals, of which the females, if classed by their external parts . . . would be placed alongside each other in the same family; but when classed by the whole rest of their organisation, certainly must be ranked in distinct orders," whereas the males "might absolutely be almost classed as species of the same genus!" (2:565). Darwin places the females of Alcippe and Cryptophialus in different orders, the males – and his language is hesitant, almost fumbling here – merely in different species. This makes females more valuable to the systematist because more different, or "perfect": "the male is here abnormal and rudimentary in its whole structure; and I believe systematists are agreed that less perfect parts (and therefore a less perfect whole) offer less valuable characters" (2:566).
 Whereas females are widely differentiated and, as it were, masters of the shell, males are servile, physically concentrated into a single organ – the penis – that produces a repetitive temporality of reproduction and death. Even when the male lacks a penis, as it does in Ibla cumingii, its entire body functions as one: "no doubt the whole body, furnished like the penis with longitudinal and transverse muscles, serves the same purpose!" (1:202). The penis is as unlocatable as any other sexual organ, yet, as an indeterminate sign (the phallus?), it organizes the morphology of the male and directs most of its activities. It saps an extraordinary amount of male energy, which leads to the "abortion" of other parts of the body to an "almost unparalleled extent." Of the twenty-one bodily segments found in every crustacean, male barnacles abort fifteen – although, like other animals, they often "retain some female characters" such as "the cementing apparatus, which homologically is part of an ovarian tube modified" (1:202-3). But male barnacles are ultimately "mere bags of spermatozoa" (1:291); they "perform their masculine functions and then perish" (2:561). Because males live such short, perfunctory lives, females continually require "fresh" sets of them, and this provides one of Darwin's most macabre narratives:
The males [of Scalpellum ornatum] from the absence of a mouth (and no doubt of a stomach), must necessarily be short-lived, and, I suppose, are periodically replaced by fresh males. In one instance, the remnants of the two great compound eyes of the larva, could be seen at the end of the pouch [of the female], opposite the orifice. The larvæ, I conclude, crawl in at the orifice . . . and scratch out the dead exuviæ of the former occupant[.] (1:252-3)
Multiple streams of males enter the female to "scratch out" the flesh of their predecessor, merge with the soft walls of their new "polyandrous establishment" (1:212), discharge sperm, and die. Darwin contrasts this static, spatialized repetition with the larger temporal process of evolution, which is the purview of females. Whereas females stretch the taxonomic limits of species, males occupy merely "complementary" or "epizoic" positions (2:15).
 Darwin claims that he can "throw no light" on the "final cause" of sexual differentiation (1:291). "Throwing light" is one of his favorite phrases to suggest evolution, however, and he uses it most famously in On the Origin of Species, where "[l]ight will be thrown on the origin of man and his history" (458).  Clearly he writes the Monograph with an eye to his future texts on evolution, including human evolution. Our understanding of what it means to be human will alter, he implies, if we throw light on our relation to the wide "diversity in the sexual relations" of barnacles (1:292), that "truly wonderful assemblage of beings . . . !" (1:212). The networks of their bodies reach and adhere to ours. They plaster ships, frustrate taxonomists, and demand new systems of knowledge. Even the cliffs of Dover, long a distinctive geological symbol of national identity, resulted from the microscopic labor of ancient barnacles that burrowed into coral with modified ovarian tubes.  Indeed, Darwin shows that the varied manifestations of sex and sexuality in barnacles are powerful sources for redefining the human.  As productive forces, they redistribute the formal dimensions of "the individual" and "the body" through simultaneous movements of interpenetration and differentiation. And as a result, human subjectivity becomes destabilized, protean. Darwin briefly depicts this new human assemblage near the end of the Monograph's second volume:
I can hardly express the perplexity which I felt when I first examined Proteolepas, and when I naturally mistook the mouth for the entire head, for I saw, as I thought, the antennæ in direct connection with the second segment of the body, posteriorly to the mouth! It was quite as monstrous and incredible an inversion of the laws of nature, as those fabulous half-human monsters, with an eye seated in the middle of their stomachs. (2:602)
Darwin quickly straightens out Proteolepas's phantasmagoric anatomy, placing its organs into the correct positions.  But by recounting his initial confusion he metaphorically sutures the temporarily unmoored organs of barnacles to a "half-human" body. Ultimately, the juxtaposition of coral and barnacles with the human body reveal how, at the intersection of scientific and literary language, marine organisms were used to invade and alter (or evolve) conceptions of the human.
 This is not to say that coral went completely unrepresented. There were many treatises on coral, including Darwin's The Structure and Distribution of Coral Reefs (1842). It was difficult, however, to comprehensively depict coral in its living environment: see, for example, Charles Kingsley's demonstration in Glaucus (1855). See also Brink-Roby and Smith, who examine the complex relation between Darwin's images and language.
 See Stott, especially xxiii-xxiv.
 I use "arborescent" and "rhizomatic" with their Deleuzean connotations in mind (see Deleuze and Guattari 3-25), although it should be remembered that the latter term emerged in the mid-Victorian period with many of the same metaphorical (see my 'Rhizomatic Subjects').
 The titles of critical works from the 1960s and 70s reveal how recently scholars continued to frame Victorian naturalism in terms of eternity: Alexander B. Adams's Eternal Quest: The Story of the Great Naturalists and Joseph Kastner's A Species of Eternity, for instance.
 See 'The Polygenetic Imagination' in How Novels Think: The Limits of Individualism from 1719-1900 (105-35).
 See Browne (473-510) and Stott for a detailed narrative of Darwin's barnacle studies.
 Darwin published a total of four volumes on barnacles: a pair on pedunculated and fossilized pedunculated barnacles (1851), and a pair on sessile and fossilized sessile barnacles (1854). I do not analyze the volumes on fossilized barnacles.
 Darwin uses the example of barnacle metamorphosis to argue against progressivism and teleology in the thirteenth chapter of Origin.
 We find a similar assertion in Origin: "it is notoriously not possible to represent in a series, on a flat surface, the affinities which we discover in nature" (406).
 In Insectivorous Plants (1875), Darwin mentions "rhizocephalous crustaceans," which are "allied" to barnacles and use "root-like processes" to feed off their hosts (288). He makes these crustaceans analogous to insectivorous plants, thereby suggesting another series of rhizomatic connections.
 Paul H. Barrett labels the following sentence, from a short paper on coral (1837), "Darwin's first published hint of his belief in evolution": "That some degree of light might thus be thrown on the question, whether certain groups of living beings peculiar to small spots are the remnants of a former large population, or a new one springing into existence" (Collected Papers 48). He continues to use the phrase in post-Origin texts: "Little light can be thrown on the gradual acquirement of . . . the power of movement" in plants (Insectivorous Plants 293).
 For the "geological power" of barnacles that burrow into coral, producing "a large portion of the chalk of Europe," see Barrett Pyrgoma genus in the Monograph (2:366-9).
 Darwin's account of barnacles offers a particularly rich resource for, or provocation to, queer theory, which until recently has tended to distrust biology: "The queerness of Darwin's barnacles is salutary not because it renders the barnacle knowable through its association with familiar human forms, but because it renders the human, cultural and social guises of queer less familiar and more captivated by natural and biological forces" (Wilson 284).
 It may be helpful to consider Darwin's ongoing struggle to reconcile ontology and epistemology (e.g., replacing the "coral of life" with the more coherent "tree of life" and making the monstrous body of Proteolepas orthoscopic) in light of Deleuze and Guattari's distinction between "nomad science" and "royal science" in A Thousand Plateaus.
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