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This study aims to describe the relationship between length and weight of the bivalves Donax cuneatus (Linnaeus, 1758) and Meretrix casta (Gmelin, 1791) along the Gulf of Mannar. A total of 1,791 individuals of two species were collected from October 2019 to December 2020. The length–weight relationship of both species has been estimated using the equation W = aLb. A common length–weight relationships, W = 0.0002 L2.8882 for D. cuneatus, and W = 0.1971 L2.3556 for M. casta were recorded. The results showed negative allometric growth in both the bivalve species. The coefficient of determination (r2) was 0.9426 for Donax cuneatus and 0.9628 for Meretrix casta. Condition factor was estimated to be less than one throughout the study period for D. cuneatus and for M. casta it ranged from 0.81 to 1.38. This study provides a mathematical equation of the relationship between length and weight, and the condition of both the species along the Gulf of Mannar, southeast coast of India.

Reconstructing diets from stable carbon isotopic signals in enamel bioapatite requires the application of a δ(13)C enamel-diet enrichment factor, or the isotopic offset between diet and enamel, which has not been empirically determined for any primate. In this study, an enamel-diet enrichment factor (ε*(enamel-diet)) of 11.8 ± 0.3‰ is calculated for chimpanzees (Pan troglodytes) at Ngogo in Kibale National Park, Uganda, based on a comprehensive isotopic assessment of previously analyzed dietary plant data and new isotopic analyses of enamel apatite. Different enamel sampling methods are evaluated to determine the potential influence of weaning on isotopic enamel values and dietary interpretations. The new chimpanzee enrichment factor and a sampling strategy that excludes teeth that formed before weaning completion are applied to all known chimpanzee δ(13)C(enamel) data, either previously published or newly derived in this study, resulting in a dietary range of almost 6‰ across all chimpanzees sampled. This new chimpanzee enamel-diet enrichment factor is then used to reassess dietary reconstructions of 12 fossil hominin species whose isotopic enamel signatures have been determined. Results reveal hominin diets that are isotopically more positive than previously reconstructed, highlighting the widespread contribution of (13)C enriched C(4)/CAM (crassulacean acid metabolism) resources in fossil hominin diets and emphasizing the broad use of these resources during human evolution. These findings stress the importance of ascertaining and employing an appropriate enrichment factor for dietary reconstructions of specific taxa as well as standardizing the sampling protocol for tooth enamel in isotopic paleodietary reconstructions.

Kenya's Baringo-Tugen Hills-Barsemoi drill site is one of six localities across Kenya and Ethiopia from which the Hominin Sites and Paleolakes Drilling Project has obtained sediment cores in an effort to investigate the role of environmental forcing in shaping human evolution. The Baringo Basin site features extensive exposures of the Chemeron Formation, which contains >100 fossil vertebrate localities including five hominin sites. The 228-m drill core, dating from ~3.29 to 2.56 Ma, is characterized by fluvio-lacustrine sediments, including multiple diatomites, with evidence of variable degrees of later pedogenic modification. In the lower part of the core (~3.29–3.04 Ma), diatoms were preserved only in very low abundance, consistent with predominantly fluvial or lake marginal environments. In contrast, five diatomites and two additional diatom-rich intervals were deposited after ~3.04 Ma, reflecting a major shift in the basin hydrology. Planktonic freshwater species dominated these diatom-rich intervals, whereas periphytic taxa were present in proportions less than 2%, suggesting that these intervals represent open-water deposition during lake highstands. Littoral or saline assemblages are largely absent throughout the core. Instead, we observed a pattern of increasing diatom frustule dissolution at the tops and bottoms of diatomite units, indicating increased alkalinity during the transgressive/regressive phases. A Na-bearing zeolite (analcime) indicative of saline waters precipitated in clastic-dominated intervals between diatomites, suggesting extreme environmental variability between lake highstands and lowstands. Diatom assemblages were consistently dominated by a few species belonging to the genera Aulacoseira and Stephanodiscus, which were at times co-dominant. We infer that assemblages dominated by Aulacoseira represent a well-mixed lake with abundant supply of silica. When Stephanodiscus was dominant, which occurred more frequently in the later freshwater phases, we infer incomplete mixing and reduced silica flux to the epilimnion (upper water layer).

Here we describe a complete skull and partial skeleton of a large cercopithecoid monkey (KNM-TH 46700) discovered in the Chemeron Formation of the Tugen Hills at BPRP Site #152 (2.63 Ma). Associated with the skeleton was a mandible of an infant cercopithecoid (KNM-TH 48364), also described here. KNM-TH 46700 represents an aged adult female of Theropithecus brumpti, a successful Pliocene papionin taxon better known from the Omo Shungura Formation in Ethiopia and sites east and west of Lake Turkana, Kenya. While the morphology of male T. brumpti is well-documented, including a partial skeleton with both cranial and postcranial material, the female T. brumpti morphotype is not well-known. This skeleton represents some of the first associated evidence of cranial and postcranial female T. brumpti remains. In addition to the complete skull, postcranial material includes elements of the axial skeleton and lower limb. While aspects of the skeleton conform to those of specimens previously assigned to T. brumpti, other features on the femur and tibia appear to differ from those previously described for this species. It is unclear whether these differences represent general variation within the T. brumpti population, variation between the sexes in T. brumpti, or the incorrect assignment of previous isolated hindlimb specimens. In total, the observable morphological features of the hindlimb suggest that KNM-TH 46700 was a terrestrial quadruped similar to modern savannah baboons (Papio). From the available evidence, it is difficult to assess whether or not KNM-TH 46700 frequently engaged in the specialized squatting and shuffling behavior observed in extant geladas (Theropithecus gelada).

Reconstructing evolutionary processes in the distant past is necessarily an inductive endeavor, typically appealing to numerous considerations thought to be relevant to the veracity of a particular conclusion. In this respect, it is essential that the considerations invoked to support hypotheses are in turn well-established truths. It is with these concerns that we sought to examine the nutritional, physiological, and archeological premises underlying the perspective that access to an aquatic diet rich in docosahexaenoic acid (DHA, 22:6n-3) was critical to human brain evolution (Carlson and Kingston [2007]: Am J Hum Biol 19:132–141). In our report investigating links between omega-3 (n-3) fatty acids and hominin encephalization, we concluded that the regular consumption of aquatic resources rich in preformed DHA may not have been essential given a varied diet of wild terrestrial foods (Carlson and Kingston [2007]). This assessment was based primarily on evidence of potential physiological adaptations in modern humans to ensure sufficient availability of DHA during critical periods of brain growth. While modern human physiology provides critical information regarding DHA as a constraint in evolving a large brain, it is also important to consistently contextualize interpretations within a framework of eclectic foraging diets rather than nutritionally limited modern agricultural populations or even modern foragers. We contend that current interpretations of Pleistocene hominin nutritional ecology do not uniquely support a shore-based foraging niche as claimed by Cunnane et al. ([2007]: Am J Hum Biol, 19:578–581). Specific issues raised in response to our article by Cunnane et al. and Joordens et al. ([2007]: Am J Hum Biol, 19:582–584) are addressed here. Am. J. Hum. Biol. 19:585–588, 2007. © 2007 Wiley-Liss, Inc.

This study compares trends in dietary composition in two large cemetery populations from the site of Kulubnarti (AD 550–800) in Sudanese Nubia. Bone collagen and bone apatite carbonate were analysed to characterise stable carbon, nitrogen and oxygen isotopes. Previous research on these cemeteries has suggested marked differences in nutritional status and health between the populations. Contrary to expectations, there were no significant relationships between any isotopic indicators related to sex or cemetery of burial, suggesting no isotopically-measurable differences in diet. However, collagen δ13C and δ15N were significantly related to age, suggesting age-related differences in protein intake or other factors. Weaning trends are gradual and variable, with the range in δ15N values exceeding 4‰ among infants/young children (0–3 yrs) and standard deviations exceeding 1‰ in collagen δ13C and δ15N for both infants/young children and subadults (4–17 yrs). This suggests varied weaning strategies among both populations and variable diets prior to adulthood. Also observed was a distinct range of isotopic carbon and nitrogen values among individuals classified as subadults (4–17 yrs), who are depleted in collagen δ13C and δ15N relative to adults. However, both infants/young children and subadults are slightly enriched in δ18O relative to adults, which suggests the presence of non-local individuals or age-related variation in water sources. While most isotopic studies of age-related dietary trends have focused on reconstructing the weaning process, this study presents findings that indicate tripartite isotopic trends distinguishing infancy, subadulthood and adulthood as separate dietary categories. Broad similarities are evident between the results presented here and those from several earlier studies of smaller populations and to nutritional studies of modern communities. These findings suggest that further research into health disparities at Kulubnarti should focus on non-dietary causal factors, and more generally, that greater attention should be paid to subadulthood in palaeodiet studies. Copyright © 2006 John Wiley & Sons, Ltd.

Major morphological and behavioral innovations in early human evolution have traditionally been viewed as responses to conditions associated with increasing aridity and the development of extensive grassland-savanna biomes in Africa during the Plio-Pleistocene. Interpretations of paleoenvironments at the Pliocene locality of Laetoli in northern Tanzania have figured prominently in these discussions, primarily because early hominins recovered from Laetoli are generally inferred to be associated with grassland, savanna or open woodland habitats. As these reconstructions effectively extend the range of habitat preferences inferred for Pliocene hominins, and contrast with interpretations of predominantly woodland and forested ecosystems at other early hominin sites, it is worth reevaluating the paleoecology at Laetoli utilizing a new approach. Isotopic analyses were conducted on the teeth of twenty-one extinct mammalian herbivore species from the Laetolil Beds (∼ 4.3–3.5 Ma) and Upper Ndolanya Beds (∼ 2.7–2.6 Ma) to determine their diet, as well as to investigate aspects of plant physiognomy and climate. Enamel samples were obtained from multiple localities at different stratigraphic levels in order to develop a high-resolution spatio-temporal framework for identifying and characterizing dietary and ecological change and variability within the succession. In general, dietary signals at Laetoli suggest heterogeneous ecosystems with both C 3 and C 4 dietary plants available that could support grassland, woodland, and forested communities. All large-bodied herbivores analyzed yielded dietary signatures indicating mixed grazing/browsing strategies or exclusive reliance on C 3 browse, more consistent with wooded than grassland-savanna biomes. There are no clear isotopic patterns documenting shifting ecology within the Laetolil Beds or between the Laetolil and overlying Upper Ndolanya Beds, although limited data from the U. Ndolanya Beds constrains interpretations. Comparison of the results from Laetoli with isotopic enamel profiles of other African fossil and modern communities reveals significant differences in dietary patterns. Relative to extant taxa in related lineages, carbon isotopic ranges of a number of Laetoli fossil herbivores are anomalous, indicating significantly more generalized intermediate C 3 /C 4 feeding behaviors, perhaps indicative of dietary niches and habitat types with no close modern analogs. Enamel oxygen isotope ranges of fossil taxa from Laetoli are consistently more 18 O depleted than modern E. African herbivores, possibly indicating more humid conditions during that interval in the past. These data have important implications for reconstructing dietary trajectories of mammalian herbivore lineages, as well as the evolution of ecosystems in East Africa. Isotopic analyses of similar or related taxa at other hominin fossil sites yield signatures generally consistent with Laetoli, suggesting that mammalian communities in East Africa were sampling ecosystems with similar proportions of browse and grass. Collectively, the isotopic dietary signatures indicate heterogeneous habitats with significant wooded or forested components in the Laetoli area during deposition of the Laetolil and Upper Ndolanya Beds. Early hominin foraging activity in this interval may have included access to forest or woodland biomes within this ecosystem, complicating traditional interpretations linking early human evolutionary innovations with a shift to savanna habitats.

Distinctive characteristics of modern humans, including language, tool manufacture and use, culture, and behavioral plasticity, are linked to changes in the organization and size of the brain during hominin evolution. As brain tissue is metabolically and nutritionally costly to develop and maintain, early hominin encephalization has been linked to a release of energetic and nutritional constraints. One such nutrient-based approach has focused on the n-3 long-chained polyunsaturated fatty acid docosahexaenoic acid (DHA), which is a primary constituent of membrane phospholipids within the synaptic networks of the brain essential for optimal cognitive functioning. As biosynthesis of DHA from n-3 dietary precursors (alpha-linolenic acid, LNA) is relatively inefficient, it has been suggested that preformed DHA must have been an integral dietary constituent during evolution of the genus Homo to facilitate the growth and development of an encephalizing brain. Furthermore, preformed DHA has only been identified to an appreciable extent within aquatic resources (marine and freshwater), leading to speculation that hominin encephalization is linked specifically to access and consumption of aquatic resources. The key premise of this perspective is that biosynthesis of DHA from LNA is not only inefficient but also insufficient for the growth and maturation demands of an encephalized brain. However, this assumption is not well-supported, and much evidence instead suggests that consumption of LNA, available in a wider variety of sources within a number of terrestrial ecosystems, is sufficient for normal brain development and maintenance in modern humans and presumably our ancestors.

The early evolutionary history of the cercopithecoids is poorly understood, primarily due to a lack of fossil material from between 15 and about 9 Ma. Cercopithecoid primate specimens from a fossil site in the Ngorora Formation of the Tugen Hills, Kenya, belong to the genus Victoriapithecus, possibly a new species. These fossils are associated with a hominoid specimen that resembles Proconsul, and another tooth of a catarrhine, also probably hominoid. The locality is BPRP#38, in the Kabasero type section of the Ngorora Formation, and well dated at 12·5 Ma. If the hominoid specimen is confirmed as Proconsul, it would be one of the most recent recorded. The relatively diverse mammal fauna from the site in some ways resembles that of Fort Ternan. The site is underlain, and not far removed in time, from one of the best fossil macro-floras in Africa, which indicates lowland rainforest conditions in this portion of the Rift Valley at 12·6 Ma.

The most significant hominin adaptations, including features used to distinguish and/or classify taxa, are critically tied to the dietary environment. Stable isotopic analyses of tooth enamel from hominin fossils have provided intriguing evidence for significant C 4 /CAM (crassulacean acid metabolism) resource consumption in a number of Plio-Pleistocene hominin taxa. Relating isotopic tooth signatures to specific dietary items or proportions of C 3 versus C 4 /CAM plants, however, remains difficult as there is an ongoing need to document and quantify isotopic variability in modern ecosystems. This study investigates the ecological variables responsible for carbon isotopic discrimination and variability within the C 3 -dominated dietary niche of a closed canopy East African hominoid, Pan troglodytes , from Ngogo, Kibale National Park, Uganda. δ 13 C values among C 3 resources utilized by Ngogo chimpanzees were highly variable, ranging over 13‰. Infrequent foraging on papyrus (the only C 4 plant consumed by chimpanzees at the site) further extended this isotopic range. Variation was ultimately most attributable to mode of photosynthesis (C 3 versus C 4 ), food type, and elevation, which together accounted for approximately 78% of the total sample variation. Among C 3 food types, bulk carbon values ranged from −24.2‰ to −31.1‰ with intra-plant variability up to 12.1‰. Pith and sapling leaves were statistically more 13 C depleted than pulp, seeds, flowers, cambium, roots, leaf buds, and leaves from mature trees. The effect of elevation on carbon variation was highly significant and equivalent to an approximately 1‰ increase in δ 13 C for every 150 m of elevation gain, likely reflecting habitat variability associated with topography. These results indicate significant δ 13 C variation attributable to food type and elevation among C 3 resources and provide important data for hominin dietary interpretations based on carbon isotopic analyses.

Fossils from a large-bodied hominoid from early Miocene sediments of Uganda, along with material recovered in the 1960s, show features of the shoulder and vertebral column that are significantly similar to those of living apes and humans. The large-bodied hominoid from Uganda dates to at least 20.6 million years ago and thus represents the oldest known hominoid sharing these derived characters with living apes and humans.

In order to further refine early hominin paleoecology at Laetoli, over 500 specimens of fossil enamel and ostrich eggshell fragments collected from the Laetolil Beds and the Upper Ndolanya Beds were analyzed isotopically. The goal was to develop a high-resolution spatio-temporal framework for identifying and characterizing foraging patterns of mammalian herbivore lineages and fossil ostriches that could be used to investigate aspects of plant physiognomy and climate through the Laetoli succession. In general, dietary patterns at Laetoli suggest heterogeneous ecosystems with both C3 and C4 dietary plants available that could support grassland, woodland, and forested communities. All large-bodied mammalian herbivores analyzed yielded dietary signatures indicating mixed grazing/browsing strategies or exclusive reliance on C3 browse, more consistent with wooded than grassland-savanna biomes. Although there were no obvious uniform dietary shifts within specific mammalian herbivore groups in the sequence, the transition from the Upper Laetolil Beds to the Upper Ndolanya Beds documents a significant increase in the representation of grazing bovids. Relative to extant taxa in related lineages, the isotopic ranges of a number of Laetoli fossil herbivores are anomalous, indicating significantly more generalized intermediate C3/C4 feeding behaviors, perhaps indicative of dietary niches and habitat types with no close modern analogs. Diets of ostriches as reflected in the isotopic composition of eggshell components indicate predominantly C3 diets but with discrete isotopic shifts within the sequence linked to taxonomic and possibly environmental change.

White and colleagues (Research Articles, 2 October 2009, pp. 65–67 and www.sciencemag.org/ardipithecus ) characterized the paleoenvironment of Ardipithecus ramidus at Aramis, Ethiopia, which they described as containing habitats ranging from woodland to forest patches. In contrast, we find the environmental context of Ar. ramidus at Aramis to be represented by what is commonly referred to as tree- or bush-savanna, with 25% or less woody canopy cover.

BACKGROUND: Major biological and cultural innovations in late Pliocene hominin evolution are frequently linked to the spread or fluctuating presence of C(4) grass in African ecosystems. Whereas the deep sea record of global climatic change provides indirect evidence for an increase in C(4) vegetation with a shift towards a cooler, drier and more variable global climatic regime beginning approximately 3 million years ago (Ma), evidence for grassland-dominated ecosystems in continental Africa and hominin activities within such ecosystems have been lacking. METHODOLOGY/PRINCIPAL FINDINGS: We report stable isotopic analyses of pedogenic carbonates and ungulate enamel, as well as faunal data from approximately 2.0 Ma archeological occurrences at Kanjera South, Kenya. These document repeated hominin activities within a grassland-dominated ecosystem. CONCLUSIONS/SIGNIFICANCE: These data demonstrate what hitherto had been speculated based on indirect evidence: that grassland-dominated ecosystems did in fact exist during the Plio-Pleistocene, and that early Homo was active in open settings. Comparison with other Oldowan occurrences indicates that by 2.0 Ma hominins, almost certainly of the genus Homo, used a broad spectrum of habitats in East Africa, from open grassland to riparian forest. This strongly contrasts with the habitat usage of Australopithecus, and may signal an important shift in hominin landscape usage.

The earliest archaeological traces and two new hominin genera (Homo and Paranthropus) appear in the late Pliocene of Africa. These first appearances may reflect novel hominin adaptive responses to shifting resource bases over geological time and/or an increasingly seasonal distribution of food over the annual cycle. Whereas regional environmental change has been documented during the Plio-Pleistocene of East Africa, it is difficult to resolve relative proportions of specific habitats at a given place and time, how these may have changed over time, and the explicit nature of particular habitats. Detailed reconstructions of paleohabitats based on paleontological, geological and geochemical evidence are necessary in order to better understand the interplay between environmental change and hominin biological and behavioral evolution.

Since Darwin situated humans in an evolutionary framework, much discussion has focused on environmental factors that may have shaped or influenced the course of human evolution. Developing adaptive or causal perspectives on the morphological and behavioral variability documented in the human fossil record requires establishing a comprehensive paleoenvironmental context. Reconstructing environments in the past, however, is a complex undertaking, requiring assimilation of diverse datasets of varying quality, scale, and relevance. In response to these difficulties, human evolution has traditionally been interpreted in a somewhat generalized framework, characterized primarily by increasing aridity and seasonality periodically punctuated by pulses or intervals of environmental change, inferred largely from global climatic records. Although these broad paradigms provide useful heuristic approaches for interpreting human evolution, the spatiotemporal resolution remains far too coarse to develop unambiguous causal links. This challenge has become more acute as the emerging paleoenvironmental evidence from equatorial Africa is revealing a complex pattern of habitat heterogeneity and persistent ecological flux throughout the interval of human evolution. In addition, recent discoveries have revealed significant taxonomic diversity and substantially increased the geographic and temporal range of early hominids. These findings raise further questions regarding the role of the environment in mediating or directing the course of human evolution. As a consequence, it is imperative to critically assess the environmental criteria on which many theories and hypotheses of human evolution hinge. The goals here are to 1) compile, review, and evaluate relevant paleoecological datasets from equatorial Africa spanning the last 10 Ma, 2) develop a hierarchical perspective for developing and evaluating hypotheses linking paleoecology to patterns and processes in early hominid evolution, and 3) suggest a conceptual framework for modeling and interpreting environmental data relevant to human evolution in equatorial Africa.

The Muruyur Beds are a substantial sedimentary deposit within a middle Miocene sequence of mafic volcanic flows associated with early stages of rifting in the central Kenyan Rift Valley. They are best represented in the Muruyur region, near Bartabwa, north of Kipsaramon, where dates range from 16·0 to 13·4 Ma. At Kipsaramon, located about 10 km south of Muruyur along the crest of the Tugen Hills, the upper Muruyur Beds are absent and the lower part can be divided into three members. Important fossil sites within Member 1 are dated between 15·8 and 15·6 Ma, and within Member 3 between 15·6 and 15·4 Ma. BPRP#89, in Member 1, is a bonebed at least 2500 m 2 in areal extent and up to 30 cm thick, which constitutes one of the richest concentrations of in situ fossil vertebrate bones in eastern Africa. BPRP#91, at approximately the same level at BPRP#89, is the source of a hominoid talus and other mammal and bird fossils. In Member 3, BPRP#122 has produced specimens of at least five individuals of the hominoid Equatorius , including a partial skeleton. The Muyuyur Beds were deposited near the western margin of a lake that was formed during the early stages of faulting and volcanism in the African Rift system. The bonebed in Member 1 appears to represent the influx of fluvially transported vertebrate and plant remains into a shallow portion of the lake. Elements of the fauna as well as stable isotopes that indicate both forest and more open environments occurred in proximity to the lake during the time of deposition of Member 1.

Bipedality, the definitive characteristic of the earliest hominids, has been regarded as an adaptive response to a transition from forested to more-open habitats in East Africa sometime between 12 million and 5 million years ago. Analyses of the stable carbon isotopic composition (delta(13)C) of paleosol carbonate and organic matter from the Tugen Hills succession in Kenya indicate that a heterogeneous environment with a mix of C3 and C4 plants has persisted for the last 15.5 million years. Open grasslands at no time dominated this portion of the rift valley. The observed delta(13)C values offer no evidence for a shift from more-closed C3 environments to C4 grassland habitats. If hominids evolved in East Africa during the Late Miocene, they did so in an ecologically diverse setting.

Cannula tubing (1·6 mm external, 1 mm internal diameter) manufactured from medical grade polyurethane containing 2% 2,4,4′-trichloro-2′-hydroxydiphenylether (‘Irgasan', Ciba-Geigy) was found to have no effect other than that seen with control (‘Irgasan'-free) tubing in the following test systems: (i) haemolysis, (ii) endothelial cell cultures, (iii) paravertebral muscle of rabbits, (iv) jugular vein of rabbits, (v) cannulation of baboons and (vi) clotting times of human platelet-rich plasma. However, the results from (iv) showed a significant amount of damage from both impregnated and control cannulae and (v) showed that all detectable ‘Irgasan' had been eluted from the portions of tubing retained within the animal before the end of the experiment, more rapidly than predicted from in-vitro studies. The rate of elution of ‘Irgasan' in vivo needs to be further investigated, and consideration should be given to developing a plastic-disinfectant combination with a slower rate of loss of disinfectant.

We have reviewed spreading infections of the dermis, with special reference to the importance of synergy in their causation. Evidence for this is accumulating from both clinical studies and from studies in laboratory animals. Necrotizing fasciitis (rapid spread over 24 h) can be caused by β-haemolytic streptococci, sometimes with Staphylococcus aureus, or by mixed infections of aerobes and anaerobes, often of gut origin. Animal studies provide good evidence that S. aureus can potentiate the β-haemolytic streptococcal infection in necrotizing fasciitis. There is also evidence that mixtures of aerobes and anaerobes can act synergistically, but animal models for necrotizing fasciitis have not been developed. Anaerobic cellulitis (variable rate of spread from hours to days) can be caused by mixed aerobes and anaerobes or by mixed clostridia. Animal studies provide good evidence for synergy in the former. Meleney's synergistic postoperative gangrene (slow spread over weeks) may be cutaneous amoebiasis: the animal model of Brewer and Meleney relates to the more rapid infections of anaerobic cellulitis.

Ten human jejunal biopsy specimens were examined by both immunofluorescence (IF) and immunoperoxidase (IP) methods to compare both plasma cell counts and the distribution of extracellular immunoglobulins. Each specimen was cut into at least two portions, one fixed in 5% formaldehyde in phosphate-buffered saline before being snap-frozen and sectioned on a cryostat for IF, the other being fixed in half-strength Zenker and embedded in paraffin wax by standard methods for IP. Plasma cell counts were comparable in the eight biopsy specimens for which they could be estimated, geometric mean values being IgA 22.9 (IF), 19.3 (IP) and IgM 9.5 (IF), 10.6 (IP). Two specimens showing subtotal villous atrophy had too much extracellular IgA for plasma cell counts to be feasible. For these the IF methods had the advantage that the extracellular immunoglobulin was more readily distinguishable from background staining.

SUMMARY Sixty‐eight breeder chickens, 4 to 12 months of age, were taken from Australian flocks that had been naturally infected with avirulent Newcastle disease virus (NDV) and transported by air to Malaysia. Nearly all the breeders had haemagglutination inhibition antibodies to NDV, at titres of from 2 to 128. Thirty‐two were inoculated intranasally with an Asian, velogenic, viscerotropic strain of NDV and all survived this challenge. Thirty‐six were exposed to contact infection with the same velogenic NDV and 2 died of Newcastle disease within 14 days. The levels of haemagglutination inhibition antibodies against NDV increased in the surviving breeders after challenge, reaching 2048 or greater in a few birds. Velogenic NDV was isolated from a cloacal swab from one clinically normal breeder 10 days after challenge by contact. Cloacal swabs taken 7 to 10 days after challenge from another 23 breeders yielded no NDV. Twenty‐four broilers, 7 weeks of age, were also transported from Australia to Malaysia. All lacked detectable haemagglutination inhibition antibody to NDV and they were from a flock with no detectable antibody to NDV. Twelve were challenged with velogenic NDV intranasally and 12 were subjected to contact challenge. All broilers died of Newcastle disease within 13 days.

Summary: A direct immunofluorescent technique with fluorescein-labeled antigens was used to examine the jejunal mucosa for specific antibody production in 23 children aged 2–25 months referred for diagnostic biopsy. Plasma cells containing antibodies to β-lactoglobulin (βLG) or bovine serum albumin (BSA) were present in 11 of 16 biopsies from patients with cow's milk protein intolerance (CMPI) but only one of eight controls, all on a diet containing cow's milk. Antibody-containing cells (ACC) constituted approximately 0.5–5% of the total (IgA + IgM) plasma cell population. Their presence did not correlate with either histologic abnormality or IgA plasma cell count. Double immunofluorescence with rhodamine-labeled antigens and fluorescein-labeled class-specific anti-human immunoglobulin sera showed the ACC to be approximately 70% IgA cells and 30% IgE cells.

Twenty-one children aged between 2 and 54 months, 14 with eczema and 7 with allergies in first-degree relatives, were referred for diagnostic jejunal mucosal biopsy for a variety of symptoms. A partial villous atrophy was found in 19 of the 21 biopsies obtained; the other 2 were normal. We report a highly significant (P less than 0.0001) lower IgA cell count in biopsies with partial villous atrophy compared with the results of our previous study of IgA and IgM plasma cells in the mucosal biopsies in children without eczema or a history of atopy matched for age and histological appearances. The IgM cell count was also lower.

The ability of a particle to remasn airborne, its ability to pass through filters, the site at which it may be deposited in the respiratory tract and the rate at which it will be removed from the air by sedimentation are all dependent on the size and density of the particle. In the course of a variety of investigations we have determined the size distribution of particles carrying various species of bacteria and fungi using the size-grading slit-sampler described by Lidwell (1959). A few of the results obtained have already been quoted in part, but the majority have not been published previously. The air sampler used separates the airborne particles into four size ranges, each of which is deposited on the surface of the agar medium contained in one of four 6 in. Petri dishes. This apparatus is constructed so that the air sample entering through a slit 7 mm. wide, impinges on to the surface of the first Petri dish at such a velocity that only the larger particles, i.e. those having an equivalent particle diametert greater than about 18,un are deposited. The air stream carrying the smaller particles is then ca.used to impinge in turn on to the surface of the three remaining Petri dishes, each time at an increased velocity and through a narrower slit, so that the minimum particle size for 50 °/0 deposition is about 10/6 for the second dish, 4,u for the third and less than l,u for the fourth and last. When the plates have been incubated the colonies found will be derived from organisms which entered the sampler carried on airborne particles corresponding approximately to the four size ranges, greater than 18ju, between 18 and lO,u, between 10 and 4ju and less than 4,sb. These size limits correspond to the value of equivalent particle diameter for 50 °/0 deposition so that there is, in fact, a considerable size overlap between the fractions. In spite of this however, reasonably good estimations of the particle size distribution within the sample and hence of the median equivalent particle diameter and of the dispersion, expressed either as an interquartile range or, if appropriate, as a standard deviation, caUn be made by plotting on probability paper the cumulative fraction oversize against the 50 °X0 collection limits, namely 18@2, 9@6 and 4 2,s6. As there are internal losses in the instrument it is necessary to correct the numbers of colonies counted in the later stages in order to arrive at a good estimate of the size distribution in the original sample. The numbers found on

Summary. Under field conditions wanted micro-organisms are often present in the air in small numbers and form a small proportion of the total flora. Selective techniques would be useful, but may be difficult to devise as airborne micro-organisms are easily damaged and passing air over organisms deposited on slit sampler plates may be traumatic. Selective media may be avoided by using indicator media or animal inoculation, or the organisms may be transferred to selective conditions after some growth has taken place. Five selective agents are discussed: specific nutrients, anaerobic incubation, temperature, antibiotics, and other added selective chemicals. A table of references for isolating individual organisms is given.

Serial CEA levels were measured in 157 patients with advanced inoperable gastric carcinoma entered in a controlled trial of cytotoxic therapy. In 49 (31%) of cases initial levels were greater than 50 ng/ml. However, serial measurements were only possible in 57 (36%) cases and results were prognostically valuable in only 15 (9.5%) of cases.

Summary: Bacterial colonies grown on objects embedded in agar sometimes show a tendency to become confluent. Glass coverslips and polytetrafluorethylene (Teflon) discs were inoculated with Staphylococcus lactis and completely embedded in serum agar. If the surface of the agar were flooded with broth before the plates were incubated the colonies had a tendency to run together, but not if the plates were incubated after thorough drying. Drying also prevented confluence occurring when broth had been injected on to the surface of the embedded object. Drying the poured plate probably acts by removing fluid squeezed out at the interface.

SUMMARYA disinfectant (2,4,4′-trichloro-2′-hydroxydiphenyl ether: Irgasan, Ciba-Geigy) was incorporated into plastic washers fabricated from ethylvinyl acetate (EVA), polyethylene, polypropylene or TPX. Plastics containing 0·2 and 2% Irgasan gave zones of inhibition on nutrient and blood agar plates seeded with micro-organisms (Staphylococcus aureus, Staph, epidermidis Escherichia coli, Proteus mirabilisorCandida albicans) even after thorough washing. Exceptionally,C. albicanswas inhibited only by 2% Irgasan, and EVA gave good inhibition only against the staphylococci. Similar washers of each plastic were implanted subcutaneously into the flanks of rabbits; before insertion each was washed, had thread woven into it and was surrounded by a plasma clot containing 2 × 108Staph. aureus. All the plastics without Irgasan gave rise to abscesses, none of the plastics impregnated with 2% Irgasan did, though from 2 out of 12 sites small numbers ofStaph. aureuswere isolated atpost mortem. Using either clinical or bacteriological criteria, the results were highly significant (P< 0.00001 andP

Summary: Jejunal biopsies obtained from 45 children referred for a variety of clinical conditions were examined histologically and by standard immunofluorescence methods. The number of plasma cells was recorded per “mucosal tissue unit.” The results showed that most of the immunoglobulin A (IgA) counts in infants under 3 yr with normal mucosa were low and that there was a rise in the number of IgA plasma cells starting after this age. Despite this, under pathologic conditions (partial villous atrophy with increased inflammatory cell infiltration - PVA) a significant rise in IgA plasma cells occurred in all age groups. Patients with coeliac disease tended to show the highest IgA as well as IgM plasma cell counts. In all other patients, IgM counts did not change significantly with age or histologic abnormalities.

The staining of eosinophils by fluorescein conjugates can be obliterated by utilising the peroxidase activity of the eosinophil. The brown reaction product of 3,4,3′,4′-tetra-aminobiphenyl hydrochloride (DAB) with hydrogen peroxide was more effective than Lendrum's stain. A satisfactory alternative to the possibly carcinogenic DAB was 2,7-fluorenediamine.

SUMMARY Respiratory syncytial virus in 1 μl drops of tissue culture homogenate on polythene gave c. 10% survival on drying and c. 1% survival over 24 h, depending on the vehicle and humidity, but showed no significant loss in liquid suspension over 3 h, or if 100 ft3 of air were blown through the suspension. When drops were deposited on nutrient agar plates there was no significant loss over a period of 3 h, even if 10 ft3 of air were passed over the surface. However, only c. 10% of the virus deposited in this way could be recovered, though 90% of bacteria could be recovered by wiping the agar firmly in the presence of liquid. Air and surface samples were taken in 13 isolation cubicles in which there was an infant suffering from acute bronchiolitis without recovery of the virus, though virus had been isolated from the throats of 8 of the infants, 5 at the time of sampling. The total volume of air sampled was 226 ft3 with liquid impingers and 1146 ft3 on agar. Hartmannellid amoebae were isolated on 2 occasions, one from the air samples and one from surface samples, and an adenovirus type 10 was isolated from the swab of a chair.

A variety of surfaces was tested for self-disinfecting action againstStaph. aureusandEsch. coliat a humidity of 42%. Surfaces which had been treated with disinfectants sometimes reduced the survival when the organisms were applied subsequently in drops of broth, but the reduction was very small unless the surface was able to absorb appreciable amounts of disinfectant and the drop of inoculum spread. When the inoculum was applied dried in cotton dust, only surfaces which evolved formaldehyde showed any activity against the bacteria. These surfaces also reduced the survival of bacteria in liquid inocula.We would like to record our thanks to Dr O. M. Lidwell for much helpful advice.

Isolation of' the amoebae Tissue culture method. Standard virus cultivation techniques were used. In outline, the method was to suck air into the liquid contained in a special modification of the slit sampler (Lidwell, 1966) and then to inoculate as much as possible of the liquid on to HeLa cells. The cells were maintained on Gey's solution with 5 per cent. rabbit serum, 0.25 per cent. lactalbumin hydrolysate, and with 100 units each of penicillin and streptomycin and 5 pg Fungizone per ml. The cells were incubated at 33"-37"C, mean c. 35°C. This technique was used because virus isolation was the original object of the work. This approach has the disadvantage of being laborious, of requiring the cell sheet to be washed after an initial short period of incubation to prevent bacteria and fungi breaking through the antibiotic cover, with the risk of losing amoebae, and of requiring the use of a fungistatic agent, that used being Fungizone, which is toxic to some amoebae (personal communication from Dr C. G. Cu 1 bertson). Agar plate method. This method is based on that used by Singh (1952) for cultivation of small free-living amoebae from the soil. Oxoid Ionagar no. 2 was dissolved in glassdistilled water to give 1.5 per cent. water agar, which was poured into 5+ in. (14 cm) diameter petri dishes. When set, the plates were dried in the hot room for about 1 hr. Klebsiella aerogenes (NCTC9667) was inoculated into a 100-ml bottle of Oxoid nutrient broth no. 2, and after overnight incubation at 37°C the bacteria were harvested by centrifugation and resuspended in about 20 ml sterile distilled water. Three millilitres of this suspension was spread on to each water agar plate and allowed to adsorb. The plates were then used for air sampling either by exposing them for 10 min. in a 20 cu. ft (570 litre) per min. slit sampler or by leaving them open to the air for various periods up to 7 hr (" settle plates "). Unless otherwise stated, exposure was by the slit-sampler technique. In some preliminary experiments, not reported here, the klebsiella suspension was killed by heating for 2 hr at 56°C before being spread on to the plates, but this treatment was discontinued as heat-killed bacteria will not support the growth of some amoebae. The plates were incubated at 30"