(1) It [the slime] may have a mechanical action... the presence of a film of soluble slime on the surface of an animal immersed in water would, like the copper sheathing of ships, mechanically prevent the occurrence of parasitic growths by continually forming a fresh surface.

(2) The slime may have a specific poisonous power.

This poisonous power, Hardy speculated, could be produced by secretions from a ‘rose-staining substance’ that he had discovered in the slime. The crustacean’s ‘poison’ might be ‘related to or form... the antecendent of the ferment by the aid of which the phagocyte [ie. ‘wander-cell’] digests its prey.’ In support of this proposal, Hardy referenced two studies that have particular relevance to this paper: Greenwood’s above-described studies of amoeba, and two papers by the Russian histologist Élie Metchnikoff. Between his appeal to shipmaking as an analogy and his discussion of wandering cells, Hardy's admittedly speculative paper drew strong connections between skin, travel, and race.

            Metchnikoff’s investigations of wandering cells had by 1892 become a key point of reference for histologists committed to the physiological study of the minute. Like Greenwood, Metchnikoff had insisted on a need to study the cell in its living condition as much as was practicable. Unlike Greenwood, he drew much more direct inspiration for his studies from the generally-accepted physiological practices of the time. Specifically, Metchnikoff had sought to vivisect cells. [footnote – Metchnikoff text – expand?] By subjecting his objects of study to the effects of a range of substances and noting the degrees of degradation that each inflicted on the former, Metchnikoff sought to differentiate between varieties of 'wandering cells'. By the time of Hardy's study, he was well recognised – if nevertheless not entirely trusted amongst especially the German scholarly community – as having identified white blood cells  (naming them 'phagocytes') as performing a defensive, 'immunizing' function within the body. Of particular note regarding the present study however is that the interpretative schema within which Metchnikoff framed his studies was one of racial typology and descent.

            As Rossiianov has shown, Metchkinoff's investigations of cells were profoundly influenced by a short period of anthropological study, in which he had characterized the peoples of the Russian hinterlands as 'developmentally arrested' along a linear, organically-determined scale of being in comparison with their [Russo-]European compatriots. Both convinced by the Rousseau-esque trope that 'savage' races were 'morally superior', and invested in a tragic sense that there could be no absolute harmony of nature in the face of their uncivilized nature, Metchkinoff took recourse to histology in the hope of reconciling these seemingly mutually contradictory facts of nature. Metchnkinoff's cell studies sought to reconcile an ideal of natural harmony with his anthropological 'discoveries' regarding the violence of primitive races.[ref. Rossiianov, 2008] Wandering cells emerged out of these efforts as representatives of an atavistic artefacts of an ancient stage of bodily evolution. Threatening both to similarly 'savage' bacterial invaders and the more highly evolved cells that made up their bodily hosts, his studies accorded wandering cells a decidedly contradictory status within the body politic.

            Hardy spent much of the 1890s investigating the contradictions of these microscopic beings. His above-mentioned comments regarding the potentially 'poisonous' capacities of the epidermal secretions of Crustacea are clearly inspired by Metchnikoff's conclusions. Yet wandering bodies would hold a somewhat different status in Hardy's investigations than those of his Russian counterpart. Metchnikoff had discovered what he believed to be deep disharmony within nature during his travels amongst 'less civilized' peoples, and subsequently sought to reconcile this belief with his prior convictions to the contrary. In contrast Hardy, who appears barely to have left Britain during the decade of his wandering cell studies, involved non-Europeans in his physiological investigations directly.

            Though Hardy framed his initial conclusions in relation to Metchkinoff's work, his earliest[check] publication[s?] in the Journal of Physiology drew at least as heavily on Greenwood's studies. These were primarily oriented towards differentiating between different types of cell in the blood of the Astacus, or common crayfish. In line with both Langley and Greenwood's prior attempts to examine cells in states as close to possible to their living conditions, Hardy emphasised that certain constituents of crustacean blood – entities that he referred to as 'exploding cells' – could only be perceived when samples were transferred from the body of an animal to a fixing agent with great rapidity. If the operation were performed quickly enough, it became possible to perceive 'cells... characterized by such extreme sensitiveness to certain stimuli that contact with a foreign body... causes an explosive disruption of their protoplasm.' This property, he found, accorded with the observation of blood in still-living Daphnia (a plankton-like crustacean through the transparent body of which blood could be observed in its living condition). Above all, Hardy emphasised, these corpuscles were characteristic of a 'primitive' state of sanguineous evolution. The blood of Daphnia, and to an extent those of crayfish too, did not display the diversity of cell-types that could be perceived in more complex animal types. Like Doughty's Bedouin tribes and Haddon's Greek, Mayan, and Chinese frets, crustacean blood presented an example of an especially early phase of evolutionary progress.

            The Journal of Physiology papers in which Hardy articulated his principal methodological commitments were not only his own work, however. The year after his Crustacea skin article appeared, another piece – this one authored by both Hardy and a collaborator, one Lim Boon Keng - was put forward.

            Lim would certainly been noticed in the Cambridge of 1892. Born in Penang, Malaysia, he had arrived in Britain as the first Malayan Queen’s Scholar in 1887, after studying at the prestigious Raffles Institution in Singapore [check]. He arrived in the city having spent [four years] as an undergraduate at the University of Edinburgh, which had awarded him the degrees of Bachelor of Medicine and Master of Surgery.[nb refs don’t cite evidence for above] By 1892 he appears to have begun to establish himself as a promising young physiological investigator [recommendation from UEdin physiol. Prof?], though it is unclear to what extent long-established presumptions regarding the inferiority of colonial peoples intellect affected British perceptions as to his academic abilities. Five years previously, just after Lim had arrived, Dew-Smith had excitedly reported to Darwin that he had ‘a real living Chinese Mandarin in the Shop today in a great purple fur cloak, shoes with wooden soles about 3 inches thick and a pig tail down to his heels.’ [from Cattermole an Wolfe, pp. 38-39] Such comments may well have had nothing to do with Lim, or for that matter racial presupposition. What it does indicate however is the sense of exoticism that non-European bodies and adornments could elicit within the academic community of 1890s Cambridge.

            That wandering cells were the subjects of Lim and Hardy’s discussion, then, is of particular interest. The concerns of two authors centred on the identification and classification of wandering cells in frogs. As with Hardy’s paper on crustacean skin, however, it was not so much the classification of cell-types that the article focused on, but the extent to which different cell-types could be identified as arising out of a single ancestral progenitor – could be, in fact, different manifestations of the same fundamental cell-type. Central to this investigation, as with Balance and Sherrington’s publication, was the possibility that one cell-type might possess the capacity to morph into another. Though wandering cells in frogs are ‘not only sharply marked off from one another by their respective structural characteristics, but also in the way that they behave when foreign substances… are present in the plasma’, there could nevertheless, Lim and Hardy suggested, ‘be no finality in the view’ that each type enjoyed ‘complete independence’. [Hardy and {Keng – standard ref?}, p. 361] Strikingly, and in sharp contrast with Hardy’s single-authored paper, their conclusions asserted differences between types of cell, and especially their lack of interchangeability: ‘no real loss of identity was observed; nothing was seen which suggests the formation of an eosinophile from a hyaline cell or vice versa’ Indeed, the two had observed ‘the devouring of eosinophile cells by the hyaline cells… One cannot conceive on the hypothesis that the eosinophile and hyaline cells represent merely phases in the development of the same cell, why the one should devour the other’.  [Hardy and {Keng}, p. 373.]