Better prepared than synthesized: Adolf Butenandt, Schering Ag and the transformation of sex steroids into drugs (1930-1946)

This paper follows the trajectory of sex steroids in 1930s Germany as a way to investigate the system of research which characterized the development of these drugs. Analyzing the changing relationship between the pharmaceutical company Schering and the Kaiser Wilhelm Institute für Biochemie headed by Nobel Prize winner Adolf Butenandt, the paper highlights the circulation of materials, information and money as much as the role of patents in shaping the study of sex steroids. Semi-synthetic analogs and metabolic pathways thus emerged as shared bio-industrial assets. This collaborative work participated in a more general 'internalization' of biology, which took place in pharmaceutical firms during the 1920s and 1930s as a strategy to standardize and develop biologicals. The construction of the hormone market was also based on Schering's collaboration with a selected group of clinicians who worked out the wide-range of indications associated with these 'natural' drugs. The paper finally shows how the wartime scientific and industrial mobilization in Nazi Germany marginalized the study of sex steroids and led to the dismantling of the KWIB-Schering network.     

Eugenic and sexual folklores and the castration of sex offenders in the Netherlands (1938–1968)

This contribution questions the positive/negative eugenics dichotomy that typifies the historiography on the eugenic movement in the Netherlands and the claim that this movement was mostly marginal because only positive eugenics was pursued. From 1938 to 1968 in the Netherlands, after a decade of debates, 400 sex offenders who had been committed to asylums for the criminally insane were ‘voluntarily’ and ‘therapeutically’ castrated. For political reasons debates on castration, meant to create consensus, eliminated any reference to or connotation with eugenics, yet these policies were unthinkable without them. This article shows that thinking about social and sexual problems and their solutions in the 1930s were permeated by eugenic folklore which in turn was informed by sexual folklore. Both eugenic and sexual lore, as common sense, or as ways of knowing, were about individual and collective loss of self control which was referred to with a catch-all phrase: ‘hypersexuality’. Although sexual classifications used in diagnosing sex offenders suggested the existence of discrete sexual categories, homosexuality for instance was not seen as a sexual alternative or as an identity but as the extent to which an offender suffered from a form of hypersexuality that threatened the fabric of society.     

The prisoner as model organism: malaria research at Stateville Penitentiary

In a military-sponsored research project begun during the Second World War, inmates of the Stateville Penitentiary in Illinois were infected with malaria and treated with experimental drugs that sometimes had vicious side effects. They were made into reservoirs for the disease and they provided a food supply for the mosquito cultures. They acted as secretaries and technicians, recording data on one another, administering malarious mosquito bites and experimental drugs to one another, and helping decide who was admitted to the project and who became eligible for early parole as a result of his participation. Thus, the prisoners were not simply research subjects; they were deeply constitutive of the research project. Because a prisoner’s time on the project was counted as part of his sentence, and because serving on the project could shorten one’s sentence, the project must be seen as simultaneously serving the functions of research and punishment. Michel Foucault wrote about such ‘mixed mechanisms’ in his Discipline and punish. His shining example of such a ‘transparent’ and subtle style of punishment was the panopticon, Jeremy Bentham’s architectural invention of prison cellblocks arrayed around a central guard tower. Stateville prison was designed on Bentham’s model; Foucault featured it in his own discussion. This paper, then, explores the power relations in this highly idiosyncratic experimental system, in which the various roles of model organism, reagent, and technician are all occupied by sentient beings who move among them fluidly. This, I argue, created an environment in the Stateville hospital wing more panoptic than that in the cellblocks. Research and punishment were completely interpenetrating, and mutually reinforcing.     

Eugenics, politics and the state: social democracy and the Swiss ‘gardening state’

This article explores the connections between eugenics, politics and the state, taking the Swiss case as a particular focus. It is argued that Switzerland provides a historical example of what Bauman [Bauman, Z. (1989). Modernity and the Holocaust. Cambridge: Polity Press.] describes as ‘gardening states’: states that are concerned with eliminating the ‘bad weeds’ from the national garden and thereby constructing sharply exclusionary national identities. The Swiss experiments with eugenics (1920s–1960s) can be seen as an example of an ongoing struggle against ‘difference’. Against this backdrop I will examine, first, the ways in which state regulation of reproductive sexuality, and other eugenic measures, became central mechanisms for dealing with cultural and other ‘differences’ in the Swiss nation. Second, I will analyse the gendered nature of such mechanisms, as well as the preoccupation with racial ‘difference’ exemplified by eugenic policies towards ‘Gypsies’. To conclude, I will examine the impact of political institutions and political ideology, in particular, social democracy, on these eugenic gardening efforts.     

Making British Cortisone: Glaxo and the development of Corticosteroids in Britain in the 1950s–1960s

Following the announcement in 1949 in the USA that cortisone offered rheumatoid arthritis sufferers effective treatment for their crippling disease, the Ministry of Health came under considerable pressure from the medical profession and the public to make cortisone available in Britain. The Ministry, therefore, urged British companies to start manufacturing cortisone. Among the several pharmaceutical firms responding to the Ministry’s request, Glaxo’s expertise in the field of vitamins gave them a head start. This paper describes the varied and flexible strategy that enabled Glaxo to maintain this head start, and the scientific and technical capabilities which the company subsequently built up, enabling them to dominate the market for corticosteroids in Britain.Among the drugs to emerge out of the Glaxo project to manufacture cortisone, which began in 1950 and later became a wider R&D programme on steroids, was the topical steroid Betnovate, launched in 1963, which remains a best-seller today. However, although it led to successful new products, Glaxo’s programme had limitations. The paper identifies a missed opportunity, in the shape of the biosynthetic route to steroid drugs, often considered as a milestone in the development of the new biotechnology. Whether or not this missed opportunity proved costly to the company is uncertain. However, it illustrates the role of technological path-dependence, and the importance of the integration between different scientific disciplines, in this case chemistry and biology, in pharmaceutical innovation.     

Naturalising purpose: From comparative anatomy to the ‘adventure of reason’

Kant’s analysis of the concept of natural purpose in the Critique of judgment captured several features of organisms that he argued warranted making them the objects of a special field of study, in need of a special regulative teleological principle. By showing that organisms have to be conceived as self-organizing wholes, epigenetically built according to the idea of a whole that we must presuppose, Kant accounted for three features of organisms conflated in the biological sciences of the period: adaptation, functionality and conservation of forms. Kant’s unitary concept of natural purpose was subsequently split in two directions: first by Cuvier’s comparative anatomy, that would draw on the idea of adaptative functions as a regulative principle for understanding in reconstituting and classifying organisms; and then by Goethe’s and Geoffroy’s morphology, a science of the general transformations of living forms. However, such general transformations in nature, objects of an alleged ‘archaeology of nature’, were thought impossible by Kant in §80 of the Critique of judgment. Goethe made this ‘adventure of reason’ possible by changing the sense of ‘explanation’: scientific explanation was shifted from the investigation of the mechanical processes of generation of individual organisms to the unveiling of some ideal transformations of types instantiated by those organisms.     

Age and size at maturity in mountain and lowland populations of the expanding moss <Emphasis Type="Italic">Pogonatum dentatum</Emphasis>

The moss Pogonatum dentatum has expanded its distribution in Fennoscandia from mountainous areas into the lowlands. This recent expansion appears to be associated with changes in important life-history parameters in female shoots. We examined shoot age and size at first production of sex organs and mature spores in P. dentatum to investigate this phenomenon. Female shoots produced mature spores for the first time in the lowlands in their second year but in their third year in the mountains. However, sex organs were produced by second year plants in both areas. There was no size difference between the mountain and lowland female shoots at the time of spore production. Among mountain females reproducing for the first time, 41% of the shoots branched, making them potentially ‘iteroparous’. Branching was not observed among lowland females. Male shoots showed no difference in production of sex organs, and were produced by second year shoots in both areas. Female shoots in the lowlands have earlier spore production and exhibit ‘semelparous’ behaviour by not producing branches. This suggests that the lowland phenotypes of P. dentatum are more ‘invasive’ than the mountain phenotypes. Earlier studies showing high rates of diaspore establishment in lowland areas also support this observation.     

Morphological Stasis of Two Species Belonging to the L-morphotype in the <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> Species Complex

Detection and characterization of sibling species complexes in zooplankton are critical to understanding their ecological responses and patterns of evolution. The taxon Brachionus plicatilis is a complex of at least 14 species with three major, deeply diverged clades, which are morphologically distinct. We studied morphometric differences between two species – B. plicatilis sensu stricto and B. ‘Manjavacas’– which belong to the L-(large) morphotype and often co-occur in ponds or lakes. B. plicatilis s.s. was on average 6% longer than B. ‘Manjavacas’. They differed significantly in the measurements related to lorica spines. A significant discriminant function relating spine measurements was found, however, individuals from each species showed extensive overlap. Our morphometric data provide additional evidence for the species status of B. plicatilis s.s. and B. ‘Manjavacas’. Since these are ancient species, our results support that a morphological stasis occurs in these taxa. We identified COI restriction sites for PvuII and KpnI which are diagnostic for B. ‘Manjavacas’ and B. plicatilis s.s., respectively. We conclude that morphometry is not useful in classifying the two species. At present, this can only be done reliably using molecular methods.     

The distribution of zinc, cadmium, lead and copper within the hepatopancreas of a woodlouse

The distribution of metals within the hepatopancreas of Oniscus asellus (Crustacea, Isopoda) from two uncontaminated sites, and two sites contaminated with zinc, cadmium and lead, has been studied by atomic absorption spectrophotometry, light microscopy, transmission and scanning electron microscopy and X-ray microanalysis. The hepatopancreas contains two types of intracellular granule. The first type, in the S cells, are spherical granules which contain copper, sulphur and calcium. In woodlice from contaminated sites, these ‘copper’ granules, also contain zinc, cadmium and lead. The second type, in the B cells, are flocculent deposits which contain iron. In woodlice from contaminated sites, these ‘iron’ granules also contain zinc and lead. Moribund woodlice from contaminated sites have large numbers of ‘copper’ and ‘iron’ granules in the hepatopancreas and a fine deposit of zinc and lead on the membranes of the cells. There are numerous microorganisms in close association with the microvillous border of the hepatopancreas of woodlice from all four sites. Within the microorganisms of Oniscus asellus from contaminated sites, there are deposits of material which contain zinc, lead, calcium and phosphorus ‘Copper’ and ‘iron’ granules could have evolved as storage sites for essential metals to be utilized when demand from the body exceeds uptake from the food. Woodlice in contaminated sites may be able to ‘detoxify’ potentially harmful amounts of essential and non-essential metals by storing them in a relatively insoluble form within these granules.     

Molecular Systematics of Middle American Cichlid Fishes and the Evolution of Trophic-Types in ‘Cichlasoma(Amphilophus)’ and ‘C.(Thorichthys)’

The majority of Middle American cichlids are placed in the informal assemblage ‘Cichlasoma.’ The group is divided into eight sections which appear to be based primarily on trophic morphology. Although several members of ‘Cichlasoma’ have been used in ecomorphological, behavioral, and biogeographic studies, no phylogenetic hypotheses for the group exist. In an attempt to develop a better understanding of the phylogenetic relationships of ‘cichlasomine’ cichlids, we examined the evolution of the trophic specialization, substratum-sifting, in two sections, ‘Cichlasoma(Thorichthys)’ and ‘C.(Amphilophus),’ to determine whether the trait reflects common ancestry. We sequenced the complete mitochondrial cytochromebgene for 19 cichlids representing six sections of ‘Cichlasoma,’ and representatives of other Neotropical Cichlidae. Additional cichlid, and noncichlid outgroup sequences were included for a total of 22 taxa. The molecular phylogeny supports the recognition of the section ‘C.(Thoricthys)’ as a natural group, and we place those cichlids in the genusThorichthys.The phylogeny also depicts ‘C.(Amphilophus)’ as paraphyletic, with substratum-sifters and generalized predators forming separate nonsister clades. We recommend that the substratum-sifting clade of the section ‘C.(Amphilophus)’ be placed in the resurrected genusAstatheros.The generalized predator clade of ‘C.(Amphilophus)’ contains only two species, ‘C. (A.) citrinellum’ and ‘C. (A.) labiatum,’ which we place in the genusAmphilophus.The phylogenetic hypotheses generated indicate that the substratum-sifting generaThorichthysandAmphilophusdo not share a common ancestor. Reconstruction of the evolution of substratum-sifting is equivocal, requiring either the independent evolution of the trait on two separate occasions or its presence in a more inclusive clade and subsequent loss in nonsubstratum sifting species.     

Hormonal regulation of female nuptial coloration in a fish

Physiological color change in camouflage and mating is widespread among fishes, but little is known about the regulation of such temporal changes in nuptial coloration and particularly concerning female coloration. To better understand regulation of nuptial coloration we investigated physiological color change in female two-spotted gobies (Gobiusculus flavescens). Females of this species develop an orange belly that acts as an ornament. The orange color is caused by the color of the gonads combined with the chromathophore based pigmentation and transparency of the skin. Often during courtship and female–female competition, a rapid increase in orange coloration, in combination with lighter sides and back that increases skin and body transparency, gives the belly an intense ‘glowing’ appearance. To understand how this increased orange coloration can be regulated we analysed chromatic and transparency effects of neurohumoral agents on abdominal skin biopsies in vitro. We found prolactin and α-melanocyte stimulating hormone (MSH) to increase orange coloration of the skin. By contrast, melatonin and noradrenaline increased skin transparency, but had a negative effect on orange coloration. However, mixtures of melatonin and MSH, or melatonin and prolactin, increased both orange coloration and transparency. This effect mimics the chromatic ‘glow’ effect that commonly takes place during courtship and intra sexual aggression. Notably, not only epidermal chromatophores but also internal chromatophores lining the peritoneum responded to hormone treatments. There were no chromatic effects of the sex steroids 17β-estradiol, testosterone or 11-ketotestosterone. We hypothesize that similar modulation of nuptial coloration by multiple hormones may be widespread in nature.     

Cytogenetic stability of <Emphasis Type="Italic">Centaurea ragusina</Emphasis> long-term culture

Centaurea ragusina L. (Asteraceae) is an endemic Croatian plant species, which developed xeromorphic characteristics as a consequence of its natural environment – vertical limestone cliffs above the Adriatic sea. Cytogenetic status of C. ragusina long-term culture (94th subculture) and C. ragusina seedlings was analysed and compared after 4 weeks of growth. Cytogenetic stability was investigated in root meristem cells of C. ragusina cultured plants originated from Pen đa (cliffs near Dubrovnik) and seedlings originated from three different localities in south Adriatic (Penđa, Pasjača – cliffs near Dubrovnik and island of Komiža) using mitotic index and mitotic and chromosomal abnormalities as parameters. Mitotic indices of cultured plants and ‘Penđa’ seedlings were similar and showed significant increase compared to mitotic indices of ‘Komiža’ and ‘Pasjača’ seedlings. Although the highest number of mitotic abnormalities was recorded in root meristem cells of cultured plants, it was only a bit higher than in root tips of ‘Pasjača’ and ‘Penđa’ seedlings, while that of ‘Komiža’ was two times lower compared to cultured plants. Pattern of analysed mitotic abnormalities was very similar in root tips of cultured plants and ‘Pasjača’ and ‘Penđa’ seedlings, with exception of ‘Komiža’ seedlings. Presented results suggest that long-term cultivation of C. ragusina has almost no effect on culture ageing considering similar distribution of scored mitotic abnormalities as in ‘Penđa’ and ‘Pasjača’ seedlings.     

Negative versus positive reinforcement: An evaluation of training strategies for rehabilitated horses

Rescued equids are often exposed to rehabilitation and training (or retraining) programmes to improve their physical and psychological well-being as well as to facilitate the re-homing process. Training uses either positive or negative reinforcement learning procedures and it is considered here that, there may be welfare implications associated with using the latter technique as it has the potential to overlay acute stress on animals with a chronic stress life history. The aim of this study, therefore, was to compare these training strategies (negative versus positive reinforcement) on equine behaviour and physiology as the first step in establishing an optimal rehabilitation approach (from a welfare perspective) for equids that have been subjected to chronic stress in the form of long-term neglect/cruelty. Over a 7-week period, 16 ponies (aged 6–18 months) were trained using either positive (‘positive’) (n = 8) or negative reinforcement (‘negative’) (n = 8) techniques to lead in hand, stand to be groomed, traverse an obstacle course and load into a trailer. Heart rate was measured (5 s intervals) on days 1 and 4 of each training week, ‘Pre’- (1 h), ‘During’ (0.5 h) and ‘Post’- (1 h) training session. Ethograms (10.00–20.00 h) outside of the training period were also compiled twice weekly. In addition, weekly arena tests (as a measure of reactivity) were also performed 1 week before and during the 7 weeks of training.Results showed significant differences between the two training schedules for some measures during the latter stages of the trial and suggested that animals trained under a positive reinforcement schedule were more motivated to participate in the training sessions and exhibited more exploratory or ‘trial and error’ type behaviours in novel situations/environments. In this context, the incorporation of positive reinforcement schedules within a rehabilitation programme may be of benefit to the animal from a welfare perspective.     

Candidatus Monilibacter spp., common bulking filaments in activated sludge, are members of Cluster III Defluviicoccus

Two alphaproteobacterial Neisser negative ‘Nostocoida limicola’ morphotypes differing slightly in their trichome diameter and filament regularity were dominant populations in the Bendigo, Victoria, Australia activated sludge community removing phosphorus (P). Neither responded to the FISH probes available for any of the other alphaproteobacterial ‘N. limicola’ morphotypes. Instead both fluoresced with the DF988 FISH probe designed originally to target alphaproteobacterial cluster II Defluviicoccus tetrad forming organisms. A 16S rRNA based clone library from this biomass revealed that the alphaproteobacterial clones grouped closely with Candidatus ‘Monilibacter batavus’ and Defluviicoccus clones in a cluster separate from the existing cluster I and II Defluviicoccus. When a FISH probe was designed against these, it only hybridized to the thinner and less abundant ‘N. limicola’ morphotype. Micromanipulation–RT-PCR was used to selectively recover the main ‘N. limicola’ morphotype and a FISH probe designed against the 16S rRNA clones generated from it showed only this filament fluoresced. From FISH based surveys, both ‘N. limicola’ variants occurred frequently in phosphorus removal activated sludge systems in Australia treating domestic waste. The data suggest that they represent two new strains of Candidatus ‘Monilibacter’, which on this evidence are filamentous members of the genus Defluviicoccus, a potential competitor for the polyphosphate accumulating organisms in these communities.     

Integrated assessment of agricultural production practices to enhance sustainable development in agricultural landscapes

This study presents an integrated assessment approach for the sustainable development of agricultural landscapes. The approach evaluates single agricultural production practices by means of environmental, economic and social indicators. To implement the approach, a mixed method was employed that combines modelling techniques and survey methods. The economic and environmental indicators were implemented within the bio-economic modelling system MODAM (Multi-Objective Decision support system for Agro-ecosystem Management) in order to assess economic performance and the effects on the abiotic and biotic environments. The modelling approach was applied to a case study in a region of north-eastern Germany, within the state of Brandenburg. In addition, the acceptance by farmers of different production alternatives that are known to have environmental benefits was examined in the case study. To allow for a direct comparison between different indicators, the results of the assessment are dimensionless index values that indicate the suitability of certain agricultural production practices with respect to an indicator. The indicator-related indices are then aggregated into an overall index of sustainability differentiating between ‘strong’ and ‘weak’ sustainability. Results are presented for exemplarily chosen production practices for sugar beet, potato and winter rape production and set aside. Depending on the underlying concept of sustainability (‘weak’ vs. ‘strong’), different production practices were identified as the most suitable ones in a given situation. This integrated assessment enables determination of positive and negative correlations between indicators. The approach allows for the identification of production alternatives that are assessed to be economically and environmentally beneficial as well as socially accepted, although at different levels.     

The elevated anthocyanin level in the shaded peel of ‘Anjou’ pear enhances its tolerance to high temperature under high light

Pigments, chlorophyll fluorescence, dark respiration, and the antioxidant system in the shaded peel of green ‘Anjou’ pear (Pyrus communis L.) and its bud mutation, red ‘Anjou’, were compared in response to high peel temperature, high light alone or in combination to determine the protective role of anthocyanins under high temperature with or without light. Under high temperature treatment alone, no difference in the maximum quantum yield of PSII (F_V/F_M) was detected between red ‘Anjou’ and green ‘Anjou’; the superoxide dismutase activity and the glutathione pool were up-regulated in green ‘Anjou’ peel but remained unchanged in red ‘Anjou’ peel. Under high temperature coupled with high light, the F_V/F_M of green ‘Anjou’ peel was decreased to a lower value than that of red ‘Anjou’, and significant interaction was detected between temperature and light for both cultivars. Furthermore, the difference in F_V/F_M between red ‘Anjou’ and green ‘Anjou’ under high temperature coupled with high light was significantly larger than that under high light alone, indicating that this larger difference was caused by the interaction between high temperature and high light as no significant difference was detected in F_V/F_M between the two cultivars under high temperature treatment alone at any sampling point. It is concluded that the elevated anthocyanin level in the shaded peel of red ‘Anjou’ does not alter its thermotolerance in the dark, but makes it more tolerant of high temperature under high light.     

Interactions of cardiac glycosides with cells and membranes Properties and structural aspects of two receptor sites for ouabain in erythrocytes

The existence of two types of binding sites for ouabain in human erythrocyte membranes is described. Receptor sites designated as ‘type I’, which may be identical to the K⁺-insensitive sites of intact cells, were detected at concentrations of ouabain as low as 10⁻⁷ M. The ‘type II’ receptor sites require the inclusion of Mg²⁺ + P_i to form complexes with ouabain; they may be identical to the K⁺-sensitive sites of intact cells. These sites were saturated at approx. 5 · 10⁻⁷ M ouabain but could not be detected at higher concentrations. The range of ouabain concentrations at which ‘type I’ receptors start to predominate (i.e. 5 · 10⁻⁸–5 · 10⁻⁷ M) was termed ‘critical digitalis concentrations’. The process of binding reached equilibrium within 1 and 4 h for ‘type I’ and ‘type II’ sites, respectively. The dissociation constant for ‘type II’ receptor-ouabain complexes was 7.6 · 10⁻⁹ M.Under similar experimental conditions, rat erythrocyte membranes exhibited only non-saturable sites.Alterations in the proportions of the two types of receptors were demonstrated by preincubation of the membranes, in the presence or absence of Mg²⁺ + P_i, prior to the addition of ouabain. In the first case, ‘type II receptor-ouabain’ complexes were stabilized at about 50% of the untreated membranes and ‘type I-ouabain’ complexes slowly approached equilibrium over a period of 24 h. In the latter instance, ‘type I’ receptors were not detected, and only ‘type II-ouabain’ complexes prevailed.     

Thermotropic ‘two-stage’ liquid crystalline crystalline lipid phase separation in microsomal membranes

The effect of temperature on native microsomal membrane vesicles isolated from Tetrahymena is investigated by wide angle X-ray diffraction. A 4.2 Å reflection, typical for lipids in the crystalline state, can be recorded in the temperature range between 0°C and 35°C. Quantitative evaluation of this reflection reveals a broad thermotropic ‘two-stage’ liquid crystallinecrystalline lipid phase separation with a ‘breakpoint’ at approx. 18°C. This ‘breakpoint’ coincides with the emergence of lipid-protein segregations in endomembranes of intact Tetrahymena cells as previously visualized by freeze-etch electron microscopy.     

Effect of epiphytes on the extent of necrotic injuries of resistant and susceptible poplar clones infected with Dothichiza populea

Poplar cuttings of a resistant clone, Populus ‘Grandis’, and susceptible clones, Populus nigra ‘Italica’ and Populus ‘Robusta’, were infected with the pathogenic fungus Dothichiza populea alone, or with the pathogen and one of five strains of epiphytes antagonistic towards it (in vitro), isolated from poplar bark. The extent of injury was examined for 28 days after infection by determining the length of necrotic patches and their area as expressed in per cent of the total area of a cutting or the area of necrotic injuries caused by the pathogen alone.All the poplar cuttings of both the resistant and susceptible clones became diseased when infected with the pathogen alone. Surprisingly enough, however, the least affected clone was the susceptible P. ‘Robusta’, in which necrotic injuries covered 28% of the total area, as against 40% and 70% in the resistant P. ‘Grandis’ and the susceptible P. nigra ‘Italica’, respectively.When the cuttings were infected simultaneously with Dothichiza populea and its antagonistic epiphytes, the diseased area in the resistant clone diminished by as much as two-thirds, and in the susceptible P. nigra ‘Italica’, by one-third in comparison with the area affected by the pathogen alone. In turn, in the susceptible P. ‘Robusta’ the introduction of three out of five epiphytes stimulated the growth of the pathogenic fungus producing on average a double increase in the necrotic area. The differences in the response of the pathogen to the presence of epiphytes recorded in the susceptible clones indicate a marked influence of the plant on the nature of interactions between its epiphytic microflora and the pathogen.