ALBERT

Notes: Abstract Existing geochronological data are reviewed and new Rb-Sr, K-Ar and 39Ar–40Ar ages are presented, including a suite of 33 mica ages from a 20 km north–south tunnel section. These data are discussed in relation to the thermal history from the overthrusting of the Autroalpine nappes c. 65 Myr ago to the present. The earliest phase of metamorphism, involving lawsonite crystallization, is associated with emplacement of these nappes. Subsequently, temperatures in the rocks beneath rose, at a mean rate of 3–6°C/Myr, until the climax of metamorphism.At high structural levels, published data indicate an age 〉 35 Myr for the metamorphic climax. In contrast, a new 39Ar–40Ar step-heating age of 23.8 ± 0.8 Myr on amphibole, from near the base of Peripheral Schieferhülle, closely approximates the age of metamorphism and provides the first clear indication that the climax of metamorphism occurred later at deeper structure levels. Following the climax, near-isothermal uplift and erosion reduced pressure to c. 1 kbar before white mica closure at 19 Myr; this implies uplift at 〉3 mm/yr.Along the tunnel section, white mica K-Ar ages vary systematically from 24 Myr to 16.5 Myr with position relative to a late 4 km amplitude dome whereas biotite Rb-Sr ages are uniform at 16.5 Myr across the whole profile; doming is thus dated at 16.5 Myr with transient uplift rates 〉5 mm/yr. At other times uplift rates were 〈1 mm/yr.

Notes: Abstract Granulites at Fyfe Hills in Enderby Land, Antarctica, crystallized at temperatures in excess of 850°C, and possibly as high as 1000°C, and at pressures of 8-10kbar during the mid to late Archaean. A number of features, including repeated retrograde metamorphism at 5.5-8kbar, retrograde reaction textures, and rimward zoning in pressure sensitive systems, suggest that following peak metamorphism the granulites stabilized at a depth of 18-26 km. After stabilization, the granulites cooled near-isobarically to temperatures of 600-700°C. Assuming a total crustal thickness of 35-40 km during this late Archaean interval of isobaric cooling, the peak metamorphic crustal thickness is estimated at 35-56 km. This estimate is significantly less than the 60-70 km obtained by summing the depths of the present levels of exposure (26-34 km) and the thickness of the crust presently beneath Fyfe Hills (approxi-mately 35km) and is, therefore, consistent with independent evidence for extensive post-Archaean thickening of the Enderby Land crust.

Notes: Abstract A Hercynian charnockite occurs within high-grade gneisses in the Agly Massif, French Pyrenees. Its thermal history has been evaluated using the Fe-Mg distribution coefticient (KD) between garnet and biotite. These minerals have different origins but similar compositions in the charnockites and host gneisses. In the charnockite, the Bi–Ga pairs are the retrograde products of Opx alteration. This Opx reaction with feldspar can be written. Opx + PI + Fluid 1(H2O + Al + K + Fe + Ti) = Bi + Ga + Q + Fluid 2(H2O + Na). The garnets are relatively Ca poor (4–2.5% grossular); they are automorphic and zoned in the gneisses and poikiloblastic in the charnockites. Both types show a retrograde rim (of few hundred microns’width) across which Fe and Mn increase as Mg decreases. The biotites show a good correlation between the octahedral cations (Ti4++ Fe2+) and (Mg2++ Al3+VI); Ti and Fe both increase, whereas Mg and AlVI decrease. There is an inverse linear correlation between Fe2+ and Mg2+ and the Fe/Mg ratio increases as Ti increases. The relation between Ti and KGa-BiDFe-Mg is less clear: it seems that KD slightly decreases as Ti increases. The equilibration temperatures of Ga–Bi pairs are discussed: the charnockite Ga-Bi pairs have equilibrated between 550°C and 600°C; whereas those of the gneisses have equilibrated between 550°C and 650°C. Two main thermal steps appear: one in the gneisses between 600-650°C and a second one in both the gneisses and the charnockites between 550°C and 600°C.

Notes: Abstract Whole-rock and mineral analyses of polydeformed mica-schist, quartzite, marble and amphibolite are presented from Signy Island, South Orkney Islands, part of the Scotia metamorphic complex. Whole-rock chemistry suggests that the amphibolites are the metamorphosed equivalent of enriched tholeiitic and alkali basalts of an oceanic intraplate basalt series. These, together with limestones and Mn-rich cherts of an oceanic island assemblage were tectonically mixed with trench or trench inner slope basin sediments in a subduction zone environment. Variation in mineral chemistry indicates an increase in temperature and decrease in pressure during metamorphism; pressures of 8 kbar and temperatures of approximately 545°C were reached during amphibolite facies metamorphism in the latter stages of deformation. These new data provide good evidence to support the previous interpretation of the Scotia metamorphic complex as a subduction complex.

Notes: Abstract The mid-Tertiary blueschists, eclogites and eclogitic gneisses of northern New Caledonia are the products of four phases of regional metamorphism and deformation (D1–D4). Omphacite, lawsonite and Mn-rich garnet isogradic surfaces were developed during the second deformation (D2) under prograde pressure and temperature conditions. Subsequent deformations (D3–D4) folded these D2 isogradic surfaces. However, within the P-retrograde, T-prograde metamorphic environment of the D4 phase, omphacite altered to albite and chlorite; as a result, a late-stage sub-horizontal isogradic surface developed for omphacite-out where this mineral preserved as relics within syn-D4 albite porphyroblasts. Other minerals that crystallized for the first time (epidote) or had rim additions (almandine phengite) during D4, also form nearly horizontal isogradic surfaces. Porphyroblastic garnet and albite contain inclusion trails, which allow their microstructural development and crystallization of the matrix to be traced from D2 to D4.Late syn-D4 the temperature increased markedly in association with an extensive exothermic decarbonation, even though the rocks were in a state of pressure retrogression. This caused considerable neocrystallization, recrystallization and growth of mattix and porphyroblasts such that, although S2 foliation crenulated by D3 and D4 is readily observable, almost all signs of stored strain due to D3 and D4 have been removed, and the deeper schists and eclogitic gneisses superficially appear to have undergone a drastic annealing recrystallization, post-dating deformation.

Notes: Abstract This, the second of two papers, represents the application of a least squares approach, discussed in the previous paper, to the generation of an internally consistent thermodynamic dataset involving 60 reactions among 43 phases, in the system K2O–Na2O–CaO–MgO–Al2O3–SiO2–H2O–CO2. We make the assumption that all the thermodynamic data, with the exception of enthalpies of formation of the phases, are well known, and solve for an internally consistent set of enthalpies which reproduces the 60, experimentally determined, phase equilibrium reactions. An important difference between our dataset and that of previous alternatives in the literature is that we are able to determine the uncertainties on, and correlations between, the enthalpies of formation for all phases in the set, and hence are able to apply simple error propagation techniques to determine the uncertainties in any phase equilibrium calculations performed using this dataset. Selection of reactions, for geothermometry and geobarometry, may be more readily made by choosing equilibria with small uncertainties in their thermodynamics. Our data are in reasonably close agreement with the high temperature molten oxide calorimetry results on silicate minerals where available, a fact which lends a degree of confidence to the results.

Notes: Abstract The Pennine rocks exposed in the south-east Tauern Window, Austria, contain mineral assemblages which crystallized in the mid-Tertiary ‘late Alpine’regional metamorphism. The pressure and temperature conditions at the thermal peak of this event have been estimated for rocks at four different structural levels using a variety of published and thermochemically derived geobarometers and geothermometers. The results are:(a) In the garnet+chlorite zone, 2–5 km structurally above the staurolite+biotite isograd: T= 490.50°C, P= 7° 1 kbar;(b) Within 0.5 km of the staurolite+biotite isograd: T= 560±300C, P=7.1 kbar;(c) In the staurolite+biotite zone, c. 2.5 km structurally below the staurolite+biotite isograd: T= 610±30°C, P=7.6±1.2 kbar;(d) In the staurolite+biotite zone, 3–4 km structurally below the staurolite+biotite isograd: T= 630±40°C, P= 6.6±1.2 kbar.The pressure estimates imply that the total thickness of overburden above the basement-cover interface in the mid-Tertiary was c. 26.4 km. This overburden can only be accounted for by the Austro-Alpine units currently exposed in the vicinity of the Tauern Window, if the Altkristallin (the ‘Middle Austro-Alpine’nappe) was itself buried beneath an ‘Upper Austro-Alpine’nappe or nappe-pile which was 7.4 km thick at that time.The occurrence of epidote + margarite + quartz pseudomorphs after lawsonite in garnet, indicates that part of the Mesozoic Pennine cover sequence in the south-east Tauern experienced blueschist-facies conditions (T〈450°C, P〈12 kbar) in early Alpine times. Evidence from the central Tauern is used to argue that the blueschist-facies imprint post-dated the main phase of tectonic thickening (D1A) and was thus a direct consequence of continental collision.Combined oxygen-isotope and fluid-inclusion studies on late-stage veins, thought to have been at lithostatic pressure and in thermal equilibrium with their host rocks during formation, suggest that they crystallized from aqueous fluids at 1.1±0.4 kbar and 420.20°C.Early Alpine, late Alpine and vein-formation P–T constraints have been used to construct a P–T path for the base of the Mesozoic cover sequence in the south-east Tauern Window. The prograde part of the P–T path, between early and late Alpine metamorphic imprints, is unlikely to have been a smooth curve and may well have had a low dP/dT overall; the decompression (presumably due to erosion) which occurred immediately before the thermal peak and possibly also earlier in the Tertiary, was probably partly or completely cancelled by the effects of early- to mid-Tertiary (D2A) tectonic thickening. The thermal peak of metamorphism was followed by a phase of almost isothermal decompression, which implies a period of rapid uplift in the middle Tertiary.The peak metamorphic P–T estimates are compared with the solutions of England's (1978) one-dimensional conductive thermal model of the Eastern Alps, and are shown to be consistent with the idea that the late Alpine metamorphism was caused by tectonic burial of the Pennine Zone beneath the Austro-Alpine nappes in the absence of extraneous heat sources, such as large intrusions, at depth.

Notes: Abstract Activity-composition relations in oligoclase near the peristerite gap are investigated in pelites from the Central Menderes Massif. The pressure of metamorphism is estimated independently, from garnet-rutile-ilmenite-kyanite-quartz, as being in the range 4–7 kbar. In the temperature range, 450–600°C approximately, both the Newton-Haselton calibration of the garnet-plagioclase-kyanite-quartz geobarometer and a related simple treatment of garnet-plagioclase-muscovite-biotite give a wide range of apparent pressures, correlated with plagioclase composition and ranging up to 11–12 kbar where the plagioclase is most sodic. This effect is attributed to failure of the activity model for plagioclase used in the Newton-Haselton treatment. It is inferred that, in the present area, γplagAn decreases with increasing XplagAn in the range An15-An25. The data can be interpreted in terms of high γplagAn in the high-albite structure at these temperatures, modified to lower values by ‘e’ordering in the more calcic oligoclases. The ordering appears to be independent of the peristerite gap, and the data do not support the interpretation of the gap as a solvus. Garnet-plagioclase assemblages are unreliable as geobarometers where the plagioclase is more sodic than approximately An20 and T 〈 700°C, and should instead be used to investigate the γ-X behaviour of the plagioclase where independent geobarometry can be used as a constraint.

Notes: Abstract Precambrian granulites of the Aldan shield in southern Yakutia, USSR, form a massif of 200,000 km2 bounded by younger fold-belts to the south, west and east. The massif consists of several blocks that reflect a primary heterogeneity of composition and differences in structural and thermodynamic evolution of different parts of the area. According to structural and petrological data the massif can be divided into two megablocks: eastern Aldan and western Aldan. They are separated by a narrow meridional fold-belt. Structural evolution of this central zone was determined by the geodynamics of the mega-blocks and was completed in the late Archaean. Towards the south, this central zone is ‘transformed’into the relatively small Sutam block adjoining the Stanovoy fold-belt that bounds the Aldan shield on the south. The Sutam block is separated from the other structural units of the Aldan shield by a system of north trending grabens filled by post-Archaean sediments.The Aldan shield is composed of Archaean high-grade granulites, while the Stanovoy fold-belt, to the south, consists of highly foliated Proterozoic rocks metamorphosed under relatively lower-grade conditions. However, relics of the granulites are mapped within the fold-belt. They contain high-grade assemblages (e.g. Opx + Sil + Qz, Sap + Qz, Opx + Gr + Sil, etc.). One of the relics, the Tokskii block, which is only slightly touched by diaphthoresis, is located in the southeastern part of the Stanovoy fold-belt. Metamorphic conditions of the Tokskii block are compared with those of the Sutam block and a similar evolution of the units is revealed.Mineral assemblages and mineral compositions do not vary within each unit, but they change in a north-south direction. The Opx + Sil + Qz assemblage has been found only in Sutam and Tok, but not in eastern Aldan and western Aldan. The Sap + Qz assemblage has been found in the Tokskii block but has not yet been found in the Sutam block. The pyrope content in garnets, from metapelites of both blocks, is significantly higher than that from the Aldan (eastern and western blocks) rocks to the north. The most important assemblages from different units of the Aldan shield have been studied using the electron microprobe in order to unravel the metamorphic evolution of the granulites and thus to deduce the thermodynamic regime of this evolution. A geodynamic model for the Aldan shield is discussed in terms of Archaean island arc development.

Notes: Abstract The high-grade meta-plutonic rocks of this study lie entirely within the Jotun Nappe of the southern Norwegian Caledonides. They are divisible on the basis of metamorphic grade and petrographic character into three units, the Storadalen Complex (SCX), the Svartdalen Gneiss (SG), and the Mjølkedøla Purple Gabbro (MPG). The SCX is a differentiated series of ultrabasic to intermediate rocks now showing only tectonite fabrics. It has been metamorphosed to spinel-Iherzolite granulite facies grade. The broadly monzonitic SG is weakly tectonized and internally differentiated. Its metamorphic grade does not exceed plagioclase-lherzolite granulite facies grade. The mis-named MPG is also broadly of monzonitic composition but it retains a coarse ophitic texture, and is of amphibolite facies grade. A gradational boundary exists between the MPG and SG, but the contact between these two units and the SCX is the steeply dipping Tyin-Gjende Fault. The three units represent a comagmatic body of mid-Proterozoic age, metamorphosed during a Sveconorwegian event and finally dismembered and upthrust during the Caledonian Orogeny.The new trace element analyses reported here show that the three rock units have remarkably similar trace element abundances and trends. K-Rb covariation shows increasing K/Rb ratios with increasing K. These patterns were produced by magmatic fractionation processes acting at deep crustal levels, possibly in the presence of a non-aqueous fluid phase. With the exception of K and Sr, close similarities exist between the rocks of this study and present-day calc-alkaline basalts and andesites from island arcs. The high K content is regarded as a primary magmatic feature, but the available data are insufficient to indicate its origin. The Sr contents are abnormally high and are ascribed to metasomatism which occurred during either high-grade metamorphism or post-climactic cooling. There are no systematic geochemical variations with metamorphic grade or degree of deformation.

Notes: Abstract The calibration of geothermometers and geobarometers should involve not only the determination of the parameters in the equation used, but also the uncertainties on, and the correlations between, these parameters. This necessitates the use of a technique such as least squares. Given the poor performance of least squares in the presence of outliers in the data, techniques for identifying outliers for exclusion—regression diagnostics, and techniques for handling data which include outliers—robust regression and jackknifing, are essential. These techniques are summarized and their importance is emphasized, and they are applied to the calibration of the garnet-clinopyroxene Fe-Mg exchange geothermometer.The experimental data of Raheim & Green (1974) and Ellis & Green (1979) are explored using regression diagnostics to discover outliers in the data. After exclusion of the two influential outliers found, a new geothermometer equation for garnet-clinopyroxene Fe-Mg exchange is derived using robust regression and based on all the data: thus, T(K) = 2790 + 10P+ 3140xca,g/1.735 + In KD where T is in Kelvin and P is in kbar. This equation, as might be hoped, is essentially identical to that of Ellis & Green (1979). Equations for calculating the uncertainty in a calculated temperature, contributed by uncertainties in the calibration, are also derived.

Notes: Abstract Zircons have been studied from different layers of migmatites (from Arvika, western Sweden and Nelaug, southern Norway) and from a paragneiss (from Arvika) associated with one of the migmatites. The main purpose of the investigation is to establish whether or not information about zircons can help in the elucidation of the parentage and rock-forming processes of migmatites.The elongation ratio of zircons from all layers is small and characteristic of sedimentary zircons. Further, the absence of characteristic colours and the growth trends of the zircons (indicated by the reduced major axes) observed in the various samples both support a sedimentary parentage for these rocks. The zircons of all layers exhibit secondary growth (overgrowth, outgrowth and multiple growth) due to metamorphism. Compared with the zircons from the paragneiss, those of the migmatite layers are more clouded and less rounded, some of them becoming opaque or even skeletal; this is especially true of the zircons from the leucosomes. These observations indicate an alteration of the original sedimentary zircons in the migmatite, especially in the leucosomes, in response to the migmatization process, previously interpreted as partial melting.

Notes: Abstract Microprobe analysis of the continuous chemical evolution of coexisting biotite-garnet and biotite-garnet-staurolite has been undertaken from interbedded micaschists of the volcanodetrital group of the Vilaine. A thermobarometric study using pertinent mineralogical equilibria reveals a complex P-T evolution, continuous throughout time, from high pressure, medium temperature (kyanite zone) to medium pressure, high temperature (sillimanite zone), then low pressure, medium temperature (andalusite zone). The T, P, fH2o and XH2o variations have been calculated from coexisting biotite-garnet pairs, and from the equilibria: paragonite (in white mica) + quartz ± albite (in plagioclase) + Al silicate + H2O; and, 3 anorthite ± grossular + 2 Alsilicate + quartz. The P-T evolution is correlated with the continuous change in composition of minerals (using P–XMg and T–XMg diagrams) and with the evolution of assemblages. This continuous P-T-time evolution, correlated with the successive formation of S1-S2 foliations, allows us to propose a P-T-time-deformation path for the micaschists and to relate the growth of its mineral components to tectonic processes.

Notes: Abstract Chemical analysis (including H2, F2, FeO, Fe2O3) of a Mg-vesuvianite from Georgetown, Calif., USA, yields a formula, Ca18.92Mg1.88Fe3+0.40Al10.97Si17.81- O69.0.1(OH)8.84F0.14, in good agreement on a cation basis with the analysis reported by Pabst (1936). X-ray and electron diffraction reveal sharp reflections violating the space group P4/nnc as consistent with domains having space groups P4/n and P4nc. Refinement of the average crystal structure in space group P4/nnc is consistent with occupancy of the A site with Al, of the half-occupied B site by 0.8 Mg and 0.2 Fe, of the half-occupied C site by Ca, of the Ca (1,2,3) sites by Ca, and the OH and O(10) sites by OH and O. We infer an idealized formula for Mg-vesuvianite to be Ca19Mg(MgAl7)Al4Si18O69(OH)9, which is related to Fe3+-vesuvianite by the substitutions Mg + OH = Fe3++ O in the B and O(10) sites and Fe3+= Al in the AlFe site.Thermodynamic calculations using this formula for Mg-vesuvianite are consistent with the phase equilibria of Hochella, Liou, Keskinen & Kim (1982) but inconsistent with those of Olesch (1978). Further work is needed in determining the composition and entropy of synthetic vs natural vesuvianite before quantitative phase equilibria can be dependably generated. A qualitative analysis of reactions in the system CaO-MgO-Al2O3-SiO2-H2O-CO2 shows that assemblages with Mg-vesuvianite are stable to high T in the absence of quartz and require water-rich conditions (XH2O 〉 0.8). In the presence of wollastonite, Mg-vesuvianite requires very water-rich conditions (XH2O 〉 0.97).

Notes: Abstract Part of the augite in the Artfjället gabbro consists of symplectitic intergrowths between augite and blebs or lamellae of orthopyroxene. Mineral compositions are consistent with formation of these symplectites by exsolution of orthopyroxene from magmatic augite at a temperature of ca. 900–1000°C. The microstructures indicate that the exsolution mechanism is discontinuous precipitation, whereby the boundary of an augite grain sweeps through a neighbouring augite, leaving the symplectite in its wake. The formation of this symplectitic augite is catalysed by the presence of an intergranular water-rich fluid phase, which promotes grain boundary mobility.

Notes: Abstract Petrological data from intercalated pelitic schists and greenstones are used to construct a pressure–temperature path followed by the Upper Schieferhülle (USH) series during progressive metamorphism and uplift in the south-west Tauern Window, Italy. Pseudomorphs of Al–epidote + Fe-epidote + albite + oligoclase + chlorite after lawsonite and data on amphibole crystal chemistry indicate early metamorphism in the lawsonite-albite-chlorite subfacies of the blueschist facies at P± 7–8 kbar. Geothermometry and geobarometry yield conditions of final equilibration of the matrix assemblage of 475±25°C, 5–6 kbar; calculations with plagioclase and phengite inclusions in garnet indicate early garnet growth at pressures of ∼ 7.5 kbar. Garnet zoning patterns are complex and reversals in zoning can be correlated between samples. Thermodynamic modelling of these zoning profiles implies garnet growth in response to four distinct phases of tectonic activity. Fluid inclusion data from coexisting immiscible H2O–CO2–NaCl fluids constrain the uplift path to have passed through temperatures of 380 + 30°C at 1.3 + 0.2 kbar.There is no evidence for metamorphism of USH at pressures greater than ∼ 7.5 kbar in this area of the Tauern Window. This is in contrast to pressures of ± 10 kbar recorded in the Lower Schieferhülle only 2–3 km across strike. A history of differential uplift and thinning of the intervening section during metamorphism is necessary to reconcile the P–T data obtained from these adjacent tectonic units.

Notes: Abstract In pelites of the central Menderes Massif, albite and oligoclase with only slight chemical zoning coexist in apparent textural equilibrium in the garnet zone, staurolite zone, and staurolite + kyanite transition zone. The metamorphic temperature range is estimated as approximately 440–550°C (from the Hodges-Spear calibration of the garnet-biotite geo-thermometer), or 440–500°C (Ganguly-Saxena calibration). While oligoclase composition at the peristerite gap changes from An22 to An14, albite also becomes more sodic (An1,5–An0.6). The slope of the albite limb is thus the reverse of that reported in other areas, and may not be a true equilibrium feature. Occurrence of kyanite, at temperatures below the crest of the gap, is due to low water activity in the presence of graphite: aH2o is estimated at approximately 0.1–0.2 from the Na content of muscovite coexisting with albite + kyanite + quartz.

Notes: Abstract The Kvamsøy pyroxenite complex consists of olivine websterite, olivine gabbro and leucogabbro-norite which have been subjected to regional high P-T (HPT) metamorphism. The metamorphism has resulted in a range of disequilibrium textures with the development of coronas and pseudomorphism of the igneous phases. Reactions between felsic and mafic mineral domains have been controlled by variable and selective diffusion of elements, resulting in a variety of local plagioclase-breakdown reactions and in significant compositional variations for the product garnet. Restricted diffusion favours transient reaction stages with garnet ± spinel ± corundum ± zoisite after calcic plagioclase in olivine gabbro and olivine websterite and garnet ± spinel ± kyanite ± quartz + sodic plagioclase in leucogabbro-norite. Complete HPT reaction has produced garnet pyroxenite which consists of garnet + diopside + hornblende + zoisite in gabbroic rocks, while amphibolitization continued during the cooling and uplift history. Grt + Ky + Pl + Qtz geobarometry suggests pressures in the range 13-16 kbar for T= 750°C, comparable with the regional eclogite-forming metamorphism.

Notes: Abstract This, the first two papers, sets out the philosophy and methods of determining an internally consistent thermodynamic dataset for minerals using the least squares method. The applicability of the least squares method is discussed, and it is applied to a small set of experimental equilibria in the system Na2O–Al2O3–SiO2–H2O. The importance is stressed of defining not only the enthalpies of formation of minerals, but also the uncertainties and the correlations among them. The system which has been used as an illustration for this paper serves as a visual guide to the method, as it is small enough to represent graphically in two dimensions. In the paper which follows, we extend the method to a system of 60 equations (experimentally determined equilibria) involving 34 unknowns (enthalpies of formation of mineral end-members).

Notes: Abstract New occurrences of crossite and jadeitic pyroxene are described from a thick metabasite unit within the upper levels of the Peripheral Schieferhülle in the Tauern Window, Austria. Unusual textures are preserved which provide evidence for the reactions and mechanisms involved in the breakdown of crossite and jadeitic pyroxene. Zones of albite and chlorite, produced by reaction between crossite and paragonite, have been preserved due to sluggish reaction kinetics during decompression from the blueschist to the greenschist facies. The zonal sequence is interpreted in terms of chemical potential gradients in Na, Mg and Al, which have been established by overstepping the equilibrium boundary. Breakdown textures of jadeite-acmite pyroxene to a symplectite of albite + hematite + actinolite, and of crossite to talc and actinolite are also described.The occurrence of crossite and jadeitic pyroxene at high levels within the Peripheral Schieferhülle implies that even upper levels of the structural sequence have undergone blueschist facies metamorphism with pressures in excess of 8 kbar during the Alpine collisional event.

Notes: Abstract The chemical evolution of garnets from pelitic rocks of probable Palaeozoic age corresponds to a complex metamorphic evolution of the host rocks.Among the almandine-rich garnets (Alm60–80), two main types of evolution can be distinguished. Early Mn-rich garnets coexisting with kyanite may be replaced by plagioclase and then, during a late stage, by biotite and/or sillimanite. The second type of evolution corresponds to an overgrowth of Mn-poor late-stage garnet on older Mn-rich garnets which corresponds to a thermal peak with sillimanite-type of metamorphism. This new garnet may appear either as an overgrowth with a strong discontinuity, or as small, new euhedral garnet or as skeletal garnet.This chemical evolution of garnet corresponds to an early collisional stage of metamorphism (of high pressure type with high Mn values) of probable Ordovician age followed by uplift and a thermal peak (low Mn values) in Devonian times.

Notes: Abstract Small unexploited copper-lead-zinc deposits, characterized by a distinctive wall-rock association of cordierite quartzite, silica-undersaturated rocks, calc-silicate rocks and impure marbles, occur in quartzofeldspathic gneisses and mafic granulites of the Strangways Metamorphic Complex, central Arunta Block, central Australia. Available data support the hypothesis that these are metamorphosed volcanogenic ore bodies. The chemical compositions of the quartzofeldspathic gneisses are comparable with those of less metamorphosed felsic igneous rocks, particularly the felsic igneous rocks emplaced in the North Australian Orogenic Province in the interval 1880–1800 Ma; and the mafic granulites are chemically similar to basalts (olivine-normative tholeiites). The wall-rock suite can be correlated from chemistry and lithological association with the suites of wall rocks found in unmetamorphosed volcanogenic ore deposits. That the protolith of the cordierite quartzites may well have been leached tuff, similar to the illite-chlorite-quartz tuff found in volcanogenic ore deposits, is also shown by retrogression of the granulitefacies assemblage: cordierite-garnet-ortho-pyroxene-biotite-quartz in the cordierite quartzites to cordierite-anthophyllite-bearing assemblages and thence to chlorite-muscovite-quartz assemblages. Lenses of silica-undersaturated rocks with spinel and, less commonly, sapphirine are interpreted as the metamorphosed equivalents of chlorite-rich pods found within leached tuffs in volcanogenic ore deposits. The wall rocks form sheet-like bodies; this suggests that they were deposited in relatively shallow water, thus precluding the formation of massive sulphides.

Notes: Abstract Polymetamorphic orthoamphibole-bearing gneisses from the vicinity of shear zones in Casey Bay, Enderby Land, Antarctica, record both the overprinting of Archaean granulite lithologies by Proterozoic metamorphism and the subsequent evolution of the latter episode during localized deformation.Mineral chemistry and zoning relationships in orthoamphibole-garnet-kyanite-quartz and later orthoamphibole-garnet-cordierite-quartz assemblages are used together with interpretation of reaction and corona textures to constrain the Proterozoic pressure-temperature path experienced by the rocks. Consideration of reaction topologies, P-T-X(Fe-Mg-A1) relationships in orthoamphibole-bearing assemblages, and standard geothermobarometry indicate that the gneisses underwent a near-isothermal decompression P-T history (steep positive dP/dT) from ± 8 kbar and 700°C to 〈5.5kbar and 650°C. This uplift path is correlated with the general effects of Rayner Complex metamorphism and deformation which occurred after 1100 Ma in a major erogenic belt south of Casey Bay.

Notes: Abstract This contribution discusses the formation of stromatic high-grade migmatites. Volume considerations require that most of the leucosome material is not added from outside the system. A segregation mechanism is necessary except in those cases where the protolith of the migmatite already had a banded structure. Although partial melting is most often advocated to provide the segregation mechanism, several arguments can be raised against high degrees of melting: mineral compositions and even zoning patterns are similar in both mesosomes and leucosomes; sufficient degrees of melting at reasonable temperatures require more than the available amounts of water; the leucosomes do not always approximate to a minimum melt composition; high degrees of melting cannot occur without an appreciable volume increase; etc. Diffusion works as a segregation mechanism at low temperatures. As diffusion rates increase exponentially with temperature diffusion must become still more important as a segregation mechanism at high temperatures. A model is suggested based on the diffusion of components in response to the gradient δσ/δx, where σ= 1/3∑3i=1 σi is the mean pressure. In homogeneously strained rocks, σ3 is larger in rock parts rich in incompetent phases than in rock parts depleted in incompetent phases. Accordingly, mechanically competent but chemically incompetent high-volume phases like quartz and feldspars stressed in micadominated parts of a rock (high σσ) migrate to parts of the rock that are depleted in mica (low σ¯). It is suggested that hornblende occurring in many leucosomes may be premigmatitic or early syn-migmatitic and due to its mechanical competency it initiates the segregation. Diffusion occurs along grain boundaries and is enhanced by small amounts of ‘intergranular fluid’;. At the best, semiquantitative estimates of diffusion rates and distances indicate that the process should work over geological times.

Notes: Abstract Two Archaean synvolcanic stocks with contact aureoles occur in the Wawa greenstone belt near Wawa, Ontario, Canada. The Gutcher Lake and Jubilee stocks consist mainly of granitoid trondhjemite with feldspar laths mottled by white mica + calcite + epidote and rimmed by clear albite. Biotite is partly or wholly pseudomorphosed by chlorite + sphene; some epidote is partly altered to calcite + chlorite. The granitoid phase grades into a foliated phase of quartz + albite + white mica + calcite + chlorite near fracture zones traversing the stocks.The alteration of the Gutcher Lake stock along its foliated margin involved addition of K2O, H2O + CO2, MnO, plus Rb; loss of CaO plus Sr; and a shift in Fe+2/Fet from 0.66 to 0.81. The alteration of the Jubilee stock along the Darwin Shear involved addition of H2O + CO2; loss of Sr; and no significant shift in Fe+2/Fet. The greenschist alteration also modified the contact aureoles bordering both stocks.One interpretation is that regional metamorphism in the Archaean overprinted a greenschist assemblage on both stocks. The alteration was intense near fracture zones and sporadic remote from fractures. Lower integrated water to rock ratios along the Darwin Shear compared to the margin of the Gutcher Lake stock may explain the comparatively lower perturbation of the element abundances and redox state of iron.

Notes: Abstract Most porphyroblasts never rotate during ductile deformation, provided they do not internally deform during subsequent events, with the exception of relatively uncommon but spectacular examples of spiralling garnets. Instead, the surrounding foliation rotates and reactivates due to partitioning of the deformation around the porphyroblast. Consequently, porphyroblasts commonly preserve the orientation of early foliations and stretching lineations within strain shadows or inclusion trails, even where these structures have been rotated or obliterated in the matrix due to subsequent deformation. These relationships can be readily used to help develop an understanding of the processes of foliation development and they demonstrate the prominent role of reactivation of old foliations during subsequent deformation. They can also be used to determine the deformation history, as porphyroblasts only rotate when the deformation cannot partition and involves progressive shearing with no combined bulk shortening component.

Notes: Three authors, representing commercial, educational and governmental photogrammetric organisations, report on their initial uses of analytical plotters.

Notes: Book reviews in this article:PROCEEDINGS OF THE INTERNATIONAL SYMPOSIUM ON SPACE TECHNIQUES FOR GEODYNAMICS. Edited by J. Somogyi. Hungarian Academy of Sciences. Sopron. Hungary.THE SURVEILLANT SCIENCE: REMOTE SENSING OF THE ENVIRONMENT. Edited by R. K. Holz. Second edition. John Wiley and Sons Ltd., New York and Chichester.DISCOVERY FROM THE AIR. By G. W. G. Allen. Edited by J. S. P. Bradford and O. G. S. Crawford with Introduction and Captions by D. N. Riley. Aerial Archaeology.PRINCIPLES OF REMOTE SENSING. By P. J. Curran. Longman, London and New York.SATELLITE OCEANOGRAPHY. By I. S. Robinson. Ellis Horwood Ltd, Chichester.THE RIGHT OF THE LINE. The Royal Air Force in the European War 1939–1945. By J. Terraine. Hodder & Stoughton, London.INDUSTRIAL HISTORY FROM THE AIR. By K. Hudson. Cambridge University Press, Cambridge.INTRODUCTION TO SATELLITE OCEANOGRAPHY. By G. A. Maul. Martinus Nijhoff, Dordrecht.REMOTE SENSING IN CIVIL ENGINEERING. Edited by T. J. M. Kennie and M. C. Matthews. Blackie and Son Ltd. Surrey University Press, Glasgow and London.

Notes: The use of small computers for on line data processing in photogrammetry has developed from the desktop calculators of the early 1970s to the microcomputers of today. The restrictions of machine code programming, small memory and limited display have been overcome. Software has been written for the PI-1A monocomparator using the BBC microcomputer for a calibration test, relative orientation, and strip formation and adjustment in the on line mode. This low cost system is suitable for training inexperienced operators or students in analytical photogrammetry, with the sequence of observation guided by operator prompts and with error checking computations displayed. Re-observations can be made on line and acceptable observations stored for input to the strip adjustment program or subsequent block adjustment.

Notes: Using modern techniques, the analysis of amateur photographs yields results with almost the same accuracy level as with metric photographs. This paper gives a classification of data processing techniques for amateur photographs and presents a well proven method for the treatment of existing amateur photographs, known as Metric Photo Perspective Transformation (MPPT). Data processing is particularly convenient and efficient if on line techniques are used. Operational procedures for the treatment of additional parameters and for the detection of blunders in a time critical on line triangulation system are proposed.

Notes: The development of an automated photographic measuring system (APM) is described. A very accurate laser beam scanning microdensitometer is used to digitise the photographic plate and a series of on line computers analyses the data during scanning. The system is available as a national facility for United Kingdom astronomers and guest investigators.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn décrit un systéme automatisé de saisie de données sur cliché. Un microdensitométre à laser numérise la plaque photographique et les données sont analysées en temps réel par ordinateur. Le systeme est destiné aux astronomes du Royaume Uni et aux chercheurs y séjournant.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungBeschreibung eines automatisierten photographischen Messsystems (APM). Ein hochgenaues Laser-Mikrodensitometer wird dabei zur Digitalisierung der Bilder benutzt, undeine Serie von On-line-Rechnern analysiert die Daten während der Abtastung. Das System steht für Astronomen im Vereinigten Königreich und anderen Forschern zur Verfügung.

Notes: Two complementary measuring instruments are described which use a very simple principle and which take three dimensional measurements or plots directly from small objects. The first instrument can achieve accuracies of ± 0·3 mm on objects whose largest dimension is 300 mm. The second can achieve ± 0·02 mm on objects smaller than a 25 mm cube.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn présente deux instruments de mesure complémentaires el de principe très simple permettant de relever dans l'espace des coordonnées sur de petits objets, le premier avec une exactitude de ± 0.3 mm sur des objets de dimension inférieure à 300 mm, le second avec une exactitude de ± 0.02 mm sur des objets de dimension inférieure à 25 mm.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungBeschreibung von zwei Zusatzmessgeräten, die auf einem sehr einfachen Prinzip beruhen und mit denen dreidimensionale Messungen oder Auswertungen von kleinen Objekten direkt durchgeführt werden konnen. Mil dem ersten Gerät kann eine Genauigkeit von ± 0,3 mm bei maximalen Objekt abmessungen von 300 mm und mit dem zweiten von ± 0,02 mm bein Objekten, die kleiner als ein 25 mm-Kubus sind, erreicht werden.

Notes: This paper outlines the technical procedures used in commercial orthophotomap production and attempts to identify some of the main differences in technical approach between orthophotomapping and conventional line mapping.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn décrit les techniques industrielles de production d'orthophotocartes et on compare leur emploi avec celui des techniques classiques.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungSkizzierung der Technologien, die bei der kommerziellen Herstellung von Orthofotokarten angewendet werden, wobei versucht wird, die hauptsächlichen Unterschiede der Techniken zur Herstellung von Orthofotokarten und konventionellen Strichkarten aufzudecken.

Notes: This paper investigates the effect of the deviation of measured points from the standard locations when carrying out a relative orientation of a stereomodel. The analytical solution of more than 100 cases was considered and, for each case, the weights for the elements of relative orientation and the correlation coefficients were evaluated. The stability of the solution was studied by calculating the characteristic roots of the matrix of normal equations.It is shown that, theoretically, the solution of the relative orientation problem can always be achieved whenever the locations of the measured points satisfy stated geometrical requirements. However, the reliability of the solution depends on their exact positions in the stereomodel. When the accuracy is too low, in practice there is no solution.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn étudié l'effet sur l'orientation relative d'un couple de variations de position des points de base. Plus de 100 cas ont été considérés et à chaque fois ont été estimées les précisions des paramètres calculés ainsi que leur correlation. On a de plus, étudié la stabilité de la solution par l'intermédiaire des valeurs propres de la matrice normale.Il n'est pas indispensable, en principe, d'imposer de contraintes précises au choix des points de base; mais de ce choix dépend la fiabilité de la solution, faible s‘il est par trop fantaisiste.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungIn der Arbeit wird der Einfluss der Abweichung der gemessenen Punkte von ihrer Standardlage bei relativer Orientierung eines Stereomodells untersucht. Dazu werden mehr als 100 analytische Lösungen analysiert und für jeden Fall die Gewichte der Elemente der relativen Orientierung und die Korrelationskoeffizienten berechnet. Die Stabilität der Lösung wurde durch Berechnung der charakteristischen Wurzeln der Matrix der Normalgleichungen abgeschätzt.Es wird gezeigt, dass theoretisch immer die Lösung des Problems der relativen Orientierung erreicht werden kann, sobald die Lage der Messpunkte die geometrischen Anforderungen erfüllt. Die Zuverlässigkeit der Lösung hängt jedoch von der exakten Lage der Punkte ab. Wenn ihre Genauigkeit zu gering ist, gibt es praktisch keine Lösung.

Notes: An automatic plotting instrument development is described where the coordinate corrections are introduced in the optical system and not at the photograph. It is suggested that the opto-mechanical devices used for correction and the proposed use of microprocessors for control of these devices offer the possibility of producing a low cost automatic plotter and stereocomparator.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn decrit une solution au probléme de la correction des coordonnées cliché pour le restituteur analytique et le stéréocomparateur: ces corrections sont introduites dans la partie optique du système et commandées par l'intermédiaire de microprocesseurs. Ceci devrait permettre d'abaisser le coût de ce type d'appareil.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungBeschreibung eines automatischen Auswertegerätes, bei dem die Koordinatenkorrekturen nicht den Bildträgern, sondern dem optischen System zugeführt werden. Es wird angenommen, dass die zur Korrektur verwendeten optisch-mechanischen Vorrichtungen und die vorgeschlagene Verwendung von Mikroprozessoren zu deren Steuerung die Möglichkeit zum Bau eines billigen automatischen Auswertegerätes und Stereokomparators bieten.

Notes: The paper deals with the analytical plotter and its impact on numerical photogrammetry. A short introductory section is followed by examples of the use of a Zeiss (Oberkochen) Planicomp C100 in analytical aerial triangulation, close range photogrammetry and the generation of digital height models. The examples demonstrate the suitability of the analytical plotter for numerical photogrammetry. Computer assistance and computer control allow for advanced data acquisition of high accuracy and speed. In addition, the minicomputer controlling the analytical plotter can be used for subsequent data processing. As a result, projects involving numerical photogrammetry can be carried out entirely in-house, without the need of an external computer.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméLe restituteur analytique et la photogrammétrie numérique. On cite des applications du Planicomp C100: aérotriangulation analytique, photogrammétrie à courte distance, constitution de modéles numériques de terrain. Efficacité, rendement, haute exactitude, tels sont les avantages du restituteur analytique. On peut d'autre part bénéficier de l'ordinateur pour toutes sortes de traitements ultérieurs.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungDer Beitrag beschäftigt sich mit dem Analytischen Plotter (AP) und seiner Auswirkung auf die Numerische Photogrammetrie. Nach einem kurzen Einführungsteil wird über den Einsatz eines Zeiss (Oberkochen) Planicomp C100 in der Analytischen Aerotriangulation, in der Nahbereichsphotogrammetrie und beim A ufbau Digitaler Höhenmodelle berichtet. Die Beispiele veranschaulichen die Eignung des AP für die numerische Photogrammetrie. Einerseits erlauben Rechnerstützung und Rechnersteuerung eine allgemeine, genaue und schnelle Datengewinnung. Darüberhinaus aber ermöglicht der, für die Steuerung des AP verfügbare Minicomputer die rechnerische Weiterverarbeitung der Messdaten. Auf diese Weise können numerisch-photogrammetrische Projekte ohne Einsatz eines externen Computers vollständig bearbeitet werden.

Notes: Book Reviewed in this article:SPHERE, SPHEROID AND PROJECTIONS FOR SURVEYORS. By J. E. Jackson.REMOTE SENSING IN ARCHAEOLOGY, CULTURAL RESOURCES TREATMENT AND ANTHROPOLOGY: THE UNITED STATES OF AMERICA IN 1979. By J. I. Ebert and T. R. Lyons.A HISTORY OF ARCHAEOLOGICAL AIR PHOTOGRAPHY IN GREAT BRITAIN. By R. R. Downey.PROCEEDINGS OF THE INDUSTRIAL AND ENGINEERING SURVEY CONFERENCE, LONDON, 1980. Edited by M. A. R. Cooper.ANALYSIS AND ADJUSTMENT OF SURVEY MEASUREMENTS. By E. M. Mikhail and G. Gracie.A HISTORY OF THE ORDNANCE SURVEY. Edited by W. A. Seymour.IN FOCUS: a rated guide to the best in photographic equipment. By J. Holtz.MAPS AND SURVEYS OF MALAWI. By C. G. C. Martin and other contributors.

Notes: When a member is thought to be domiciled or employed abroad, the name of the country has been added. Errors and omissions should be notified to the Honorary Secretary.

Notes: A brief review of work on airborne metric camera movement has been made. The tolerances for permissible image movement set by various investigators are discussed.The biggest single fault with most metric camera mountings in current use is that the centre of gravity of the camera is well above the line of action of the resilient elastic restoring forces. This results in coupling between the linear vibration of the airframe and the angular motion of the camera. There is a need for a simple device which can be attached to a survey camera in order to record angular motion during actual survey missions.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméAprès une brève revue des travaux concernant les mouvements d'une chambre de prise de vue en vol, on discute les tolérances couramment admises pour ces mouvements.Le défaut de montage le plus fréquemment rencontré, est que le centre de gravité de la chambre est au-dessus de la ligne d'équilibre des forces agissantes.D'où un couplage entre la vibration longitudinale du porte-chambre et le mouvement angulaire de la chambre. Il faudrait créer un dispositif simple permettant d'enregistrer ce mouvement pendant les vols.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungEs wird ein kurzer Überblick über die Arbeiten zur Bewegung von Luftbildmesskammern gegeben. Die von verschiedenen Autoren für die zulässige Bildwanderung angegebenen Toleranzen werden diskutiert. Der schwerwiegendste Fehler, der am meisten bei den gegenwärtig verwendeten Messkammern auftritt, ist der, dass der Kammerschwerpunkt über der Wirkungslinie der schwingungsdämpfenden Kräfte liegt. Daraus resultiert eine Paarung der linearen Vibration mit der Winkelbewegung der Kammer. Es besteht Bedarf für eine einfache Vorrichtung, die an einer Messkammer befestigt werden kann, um die Winkelbewegungen während des Bildflugs aufzuzeichnen.

Notes: A philasterine scuticociiiate 82-133 μm in length and 29-51 μm in width is described from the intestine of the solitary tunicate Ascidia ceratodes. It has 44 somatic kineties, an anterior dorsal bald spot, and a triangular scutico-vestige which lies above recessed posterior oral polykinetids.

Notes: Saudi Arabian camels {Camelus dromedarius) are infected with three species of Eimeria: E. dromedarii (28.4%), E. rajasthani 〈 22.2%), and E. cameli (19.2%); 41.6% of the animals examined were positive. The highest prevalence of infection was reported in the western region of the country. Mixed infection with two Eimeria species is most common; E. dromedarii was most frequently and generally the most predominant species. Eimeria dromedarii and E. rajasthani are described for the first time from Saudi Arabian camels.

Notes: Tetrahymena of the T. pyriformis complex collected from varied habitats in Malaysia, Thailand, and The People's Republic of China include strains of the micronucleate species T. americanis and T. canadensis and the amicronucleate T. Pyriformis and T. elliotti. Two new breeding species are described—T. malaccensis from Malaysia and T. asiatica from China and Thailand. Two wild selfers from China and some of the amicronucleate strains from all three countries fall into isozymic groups similar to named micronucleate and amicronucleate species. The T. patula complex is represented by two groups of clones from Malaysia that fit the morphological description of T. vorax. They, however, have radically different isozymic electrophoretic patterns and both groups differ from those of previously described T. vorax. As their molecules indicate relationships to other “T. vorax” strains as distant as that between T. vorax and T. leucophrys, they are considered to be new species, T. caudata and T. silvana. A third new breeding species, T. nanneyi, was identified among strains previously collected in North America. Viable immature progeny were obtained from the new strains of the five breeding species. Maximum temperature tolerances were determined for the new strains of four of the breeding species.

Notes: The cellular bases of the powerful cytolytic activity of the human protozoan parasite Entamoeba histolytica were explored by studying the effect of the virulent strain HM1:IMSS on epithelial monolayers of MDCK cells using a combination of time-lapse microcinematography and transmission and scanning electron microscopy. Early alterations of the epithelial cell membranes were detected by measuring changes in the transepithelial electrical resistance of MOCK monolayers mounted in Ussing chambers. The aggressive mechanism of E. histolytica trophozoites was found to be a complex, multifactorial phenomenon that included hit-and-run damage to the plasma membrane of effector cells mediated through contact, phagocytosis of lysed or apparently intact, but detached, MDCK cells, and inlracellular degradation of ingested cells. Following contact with amebas, the epithelial monolayers showed a pronounced lowering of transepithelial resistance, opening of tight junctions, distortion of microvilli, surface blebbing, and the presence of minute focal discontinuities in the plasma membrane. There was no evidence of amebic exocytosis, membrane fusion, or junction formation between the parasite and host plasma membranes. Although modifications in the epithelial cell membranes usually preceded lysis, the cytolytic activity of the parasite did not exclusively involve damage to the plasma membrane of the cultured host cells but also was mediated by avid phagocytosis, the displacement and separation of neighboring cells by means of pseudopodial activity, and the “pinching-off” of the peripheral cytoplasm of epithelial cells.

Notes: Five new species of myxosporean parasite are described from cultured tilapias in Israel. These are: Myxosoma sarigi. Myxosoma equatorialis, Myxobolus israelensis. Myxobolus agolus, and Myxobolus galilaeus. The first four were found in hybrids of Oreochromis aureus x Oreochromis niloticus while Myxobolus galilaeus was found in Sarolherodon galilaeus. In addition, M. sarigi. M. israelensis, and Myxobolus sp. were also found in S. galilaeus. In the light of the present study, the taxonomy of myxosporean infections in tilapias is modified. Mature spores may localize in the melano-macrophage centers of the spleen and kidney where ihey may eventually be destroyed. Nc cases of mortality have so far been associated with these parasites.

Notes: Oocysts of Caryospora cobrae n. sp. were isolated from an Indian cobra, Naja naja Linnaeus from West Bengal, India. The sporulated oocysts were spherical to subspherical, 16.5-19.5 times 16.5-18.0 μm, and had a micropyle but lacked a polar granule and oocysl residuum. The sporocysts were piriform, measuring 12.0-16.5 times 9.0−12.8 μm; a Stieda body and sporocyst residuum were present.

Notes: World Health Organization. 1984. The Leishmaniases.

Notes: After a thin membranous envelope surrounding the cell body and cilia of Colpoda steinii has been formed, the main mass of the proteinaceous cyst wall is deposited without exocytosis. It can be composed of two layers, the denser and wrinkled ectocyst and the smooth-walled endocyst; however, the ectocyst may be missing. Evidence is presented that ecto- and endocyst are formed from vesicles derived from abundant rough endoplasmic reticulum which appears at the time of wall formation. The cilia are retained and become embedded in the peripheral cytoplasm. Synthesis of RNA and protein is required as actinomycin C and cycloheximide block cyst formation. Calcium is required during a sensitive phase prior to encystment.

Notes: Trypanosoma brucei strain 366D trypomastigotes grown at 37°C in the presence of a human fibroblast cell line formed foci underneath the feeder cells whereas trypanosomes grown in the presence of a human epithelial cell line grew only in the culture supernatant. A culture system was developed to study the differentiation of bloodstream trypomastigotes grown in the epithelial cell system into procyclic trypomastigotes at 27°C. The morphological differentiation into the procyclic form was complete by 48 h. Cell division did not occur until 30–40 h after transfer to 27°C. Various characteristics of this system were examined, including the effect of the feeder layer, the type of medium, the presence of the metabolites cis-aconitate and citrate, the preadaptation period, and the trypanosome cell concentration. The respiration of the recently differentiated procyclic cells was less sensitive to inhibition by CN-than that of established procyclic forms, implying a delayed appearance of complete mitochondrial oxidative pathways. This trypanosome differentiation system has the advantage that the animal host is not needed and the entire process is carried out in in vitro culture.

Notes: The flagellated protozoan, Giardia agilis, was isolated from tadpole small intestine and examined by scanning electron microscopy and interference reflexion microscopy. The general morphology of the G. agilis trophozoite is similar to G. muris and G. duodenalis, but with modifications that reflect its elongated form. Interference reflexion microscopic analysis of attachment of G. agilis reveals a pattern of focal contacts by the lateral crest of the ventral disc, the ventrolateral flange, the lateral shield, and by numerous microvillus-like appendages found along the lateral border of the trophozoite. The pattern of focal contacts was observed to be dynamic; trophozoites were observed to make and break the focal contacts in a relatively short time and to glide along the surface of the substratum without breaking focal contacts.

Notes: The fine structure of stages in mitosis in a colorless euglenoid, Anisonema sp., reveals that chromosomes remain condensed throughout the life cycle and are attached to the nuclear envelope at interphase. The onset of mitosis is marked by the anterior migration of the nucleus towards the base of the reservoir and by elongation of the nucleolus. The nuclear envelope persists throughout mitosis. Microtubules are generated in the peripheral nucleoplasm adjacent to the envelope and attach to the chromosomes while they are still associated with the envelope. The region of microtubular contact develops into a distinct layered kinetochore as the developing spindle with attached chromosomes separates from the nuclear envelope and moves into the nucleoplasm. The mature spindle consists of a number of subspindles each containing about 8–10 microtubules and a few associated chromosomes. Both chromosomal and non-chromosomal microtubules are present in each subspindle and extend towards the envelope terminating at or near the nuclear pores. Chromosomal segregation is concomitant with nuclear elongation. By late division, an interzonal spindle develops in the dumbbell-shaped nucleus and nucleolar separation occurs. Continued invagination of the nuclear envelope in the region of the interzonal spindle eventually separates the daughter nuclei. A remnant of the interzonal spindle persists in the cytoplasm until cytokinesis.

Notes: The fine structure of exoerythrocytic merogony of Plasmodium berghei was studied after perfusion-fixation of rat livers from 51 h post-inoculation onwards. Meroblast formation was effected by clefts originating from the parasite plasmalemma and by fusion of vacuoles with each other. Invaginations at the periphery resulted in labyrinthine structures providing the parasites with an enormous increase in surface area, which might facilitate exchange of metabolites. When the parasitophorous vacuole membrane collapsed, the newly formed merozoites were lying free in the hepatocytic cytoplasm, which degenerated until the merozoites were sticking together by a stroma, obviously a remnant of the host hepatocyte. Groups of merozoites, still kept together by the spongy stroma, were subsequently released in the bloodstream. At 53 h most of the developmental stages leading to the release of merozoites could be found and thereafter parasite numbers decreased while large granulomas became apparent.

Notes: This study examines previously undescribed general and cytopharyngeal features of the genus Entodinium. The cytopharynx contains three types of microtubular ribbons underlying the cytostomal membrane as well as a loose palisade of nematodesmata. A protoesophagus composed of microtubular bundles associated with a fibrous wall lies internally to one side of an extrusible peristome on which the adoral zone of syncilia (AZS) is mounted. Macronuclear structures are very similar to those of other ophryoscolecids. The micronucleus has chromatin bodies forming a compact mass but lacks the thick wall found in other species. A tubular spongiome surrounds the contractile vacuole and the cytoproct is relatively undifferentiated. Cortical structure follows the usual five-layered ophryoscolecid pattern with subcortical barren kinetosomes arranged into indistinct kineties. The infraciliature of the AZS has kinetosomes set upon a subkinetal rod and with associated bifurcated kinetodesmata and transverse microtubules, some of which extend into the cytopharynx. Components newly described for Entodinium are the one to three postciliary microtubules and the interkinetosomal centro-lateral strand, all of which are present in other species of ophryoscolecid ciliates. The infraciliature of the paralabial ciliary tuft shows similar components to that of the main AZS, but lacks the subkinetal rod. The microtubular components of the cytopharynx are discussed in relation to the “alimentary” structures in other ophryoscolecids, and a relationship of these structures to dietary differences is suggested.

Notes: Cryptosporidium parvum oocysts isolated from calf feces were examined by scanning electron microscopy during excystation. Intact C. parvum oocysts were spheroid to ellipsoid, ≅3.5 × 4.0 μm, with length: width ratio = 1.17. The oocyst wall had a single suture at one pole, which spanned 1/3 to 1/2 the circumference of the oocyst. During excystation the suture dissolved, resulting in a slit-like opening, which the sporozoites used to exit the oocyst. Sporozoites were 3.8 times 0.6 μm and had a rough outer surface.

Notes: Special ultrastructural characteristics of the haptorid soil ciliate Enchelydium polynucleatum Foissner, 1984 are the restriction of the parasomal sacs to the area of the “brush” and finger-like projections of the food vacuole membrane into the lumen of the vacuole. The general organization of the infraciliature is similar to that of Spathidium and some buetschliids because the anterior ends of the somatic kineties are condensed and obliquely bent. Enchelydium is similar to haptorids and buetschliids in possessing monokinetid somatic fibrillar structures with the classical fibrillar associates: 1) a short kinetodesmal fiber; 2) two transverse microtubular ribbons; 3) a long postciliary microtubular ribbon; and 4) a system of overlapping subkinetal microtubules, which seems to be absent in the buetschliids. Unlike Spathidium and all other haptorids so far investigated ultrastructurally, serial sections show that there are no oral dikinetids, as in the endocommensal buetschliids and balantidiids. Instead, three to six anterior kinetids in each ciliary row have nematodesmal bundles extending into the cytoplasm and surrounding the cytopharynx. These kinetids lack cilia and all fibrillar associates except enlarged transverse ribbons, which extend anteriorly and inwards to support the cytopharynx. Other similarities between the buetschliids and Enchelydium are the conspicuous rough endoplasmic reticulum and abundant sausage-like vesicles in the oral region. As in other haptorids, Enchelydium has two types of toxicysts and one type of mucocyst. These observations strongly suggest that Enchelydium belongs to the ancestral stock of both the Haptorida and the Archistomatida. The similarities in the somatic and oral infraciliature and ultrastructure of the Haptorida and the Archistomatida suggest that they belong to the same subclass, Haptoria Corliss, 1974.

Notes: Resting cysts and the excystment process in the freshwater ciliate Euplotes muscicola were studied by both light and scanning electron microscopy. Groups of distinctly crested resting cysts adhere to the substrate. Silver-stained preparations reveal surface conservation of dorsal kinetosomes and dorsal argyrome while ventral organelles are directed inward. Excystment involves the development of an expanding excystment vacuole concurrent with a localized thinning on the dorsal cyst wall surface. Cells exit through the pre-formed ostiole, mid-dorsal region first, initially by the force of cytoplasmic streaming, but later aided by cirral movement. Newly emerged cells retain the excystment vacuole and show no dorsal ridging. As the cell expels its excystment vacuole and partially unfolds, normal trophont morphology is re-established. Both cyst structure and cyst typology have implications for hypotrich taxonomy.

Notes: The cytosol fraction of a symbiont-bearing strain of Amoeba proteus exerted a lethal effect when injected into symbiont-free amoebae of the original strain. The lethal factor appeared to be a protein with a molecular weight of over 200,000. While the effect of the lethal factor on the nucleus was reversible, the host cytoplasm was permanently damaged so that it could not form a viable cell when combined with a normal nucleus.

Notes: Laybourn-Parry, Johanna 1984. A Functional Biology of Free-Living Protozoa.

Notes: Seven monoclonal antibodies specific for mammalian β-tubulin demonstrate the microtubule cytoskeleton of Toxoplasma gondii and Leishmania donovani by indirect immunofluorescence microscopy. Immunoblots of T. gondii and L. donovani proteins separated by SDS polyacrylamide gel electrophoresis confirm the specificity of the monoclonal antibodies for tubulin. Differential staining of flagellar and subpellicular microtubule populations was not seen in L. donovani with these antibodies. All seven antibodies also detected the subpellicular microtubules of T. gondii, but the polar ring and conoid of this organism was not visualized by any of them. This technique provides a rapid and specific way to assess microtubular organization in whole organisms.

Notes: Lee, J. J., Hutner, S. H. & Bovee, E. C., eds. 1985. An Illustrated Guide to the Protozoa.

Notes: .Attention, perhaps overdue, is drawn to the extent and significance of endosymbionts (xenosomes sensu lato) in the cytoplasm and nuclei of many protozoa from diverse taxonomic groups. Even more importantly, recent advances in the study of such intimate associations are reviewed and discussed and their impact on broader problems of cell biology and evolution are stressed. Workers inside and especially outside the fields of protozoology and parasitology have often neglected such data, failing to appreciate their relevance to significant problems in their own fields of investigation. The major topics covered by speakers in the Symposium (to which this paper serves only as an introduction) include the following, in order of their presentation: terminology for the symbiont-host relationship and a brief overview of the field; the evolutionary problem of the origin of contemporary associations, including cell organelles such as mitochondria and plastids; the adaptive value of endosymbionts to their protozoan hosts; mechanisms of establishment, maintenance, and integration of such foreign bodies/invaders in their unicellular eukaryotic host cells; and the extent of algal and bacterial endosymbioses in diverse protozoan groups. In all papers, the principal relatively well studied complexes used as examples are the following: various kinds of algae in the larger foraminifera and in ciliates, radiolarians, and acantharians; the several types of bacteria in the cytoplasm of Amoeba and of Pelomyxa; the endonuclear bacterial symbionts of Paramecium; the cytoplasmic prokaryotes in Paramecium and in Parauronema; and the methanogenic bacteria of certain ciliates.

Notes: .It is generally accepted that in symbiotic systems involving algal species as cellular endobionts there is some positive benefit to the host organisms. In this paper special consideration is given to the larger foraminifera, protozoa that serve as very useful model systems for the study of aspects of inter/intracellular integration and adaptation—living, as they do, in nutrient-limited but well illuminated shallow tropical seas and containing endosymbiotic algae in abundance. A considerable amount of information is now available on physiological as well as morphological adaptations of the host species to pigmented protists representing diverse algal divisions (phyla). Brief mention is also made of bacterial endosymbionts of certain ciliates.

Notes: .In this paper the concept of “xenosome” is greatly expanded from its current usage, which has been based on its application during the past 10 years by Soldo and co-workers solely to certain bacterial invaders of the cytoplasm in species of a single genus of marine scuticociliales. The author proposes that the term now be considered to embrace all DNA-containing, membrane-bounded bodies or organelles—prokaryotic or eukaryotic in original nature—found within the cytoplasm or nucleus of eukaryotic cells of any or all kinds, whether the occupation (“colonization”) is temporary and transient or permanent and stable. Thus, virulent or pathogenically infectious organisms can be included as well as the commonly recognized cell endosymbionts sensu stricto, which are often mutualistic in nature. Of significance, such “normal” cell organelles as plastids, mitochondria, and even nuclei may also be embraced by this expanded definition of xenosome, based on the conjecture that these inclusions might have been “alien” or “foreign” extracellular, independent, free-living organisms in their own past evolutionary histories. The author's enlarged concept and unifying principle allows more meaningful comparative consideration of the numerous and diverse kinds of xenosome-host interrelationships, many of which involve species of protozoa and algae from a large number of the taxonomic groups comprising the kingdom Protista.

Notes: Protozoa are now being recognized as important members of planktonic food webs. This is due to the inclusion of microbial links in our paradigm of trophic relationships. Heterotrophic microflagellates and ciliates are major grazers of bacteria. They can stimulate production through nutrient recycling and can transform microbial production into larger particles, which are then available for macroconsumers. In this paper we add new groups, the small (〈 20 μm) ciliates and myxotrophic flagellates, to the planktonic food web.

Notes: .Important progress has been made in recent years towards better understanding of the establishment and maintenance of endosymbiosis in protozoa and of the eventual integrative mechanisms involved. Still, many problems remain to be investigated more thoroughly. In this paper, while treating and reviewing the subject broadly, particular and more detailed attention is given to three selected systems: endonuclear symbiosis by Holospora bacteria in Paramecium; algal (Chlorella) relationships with the “green”Paramecium (P. bursaria) as host; and the rod-shaped bacteria found in the cytoplasm of Amoeba proteus. Data concerning the physiology of food vacuoles, membrane transport, photobehavior, recognition specificity, enzyme activity, and the like are presented and reviewed and discussed in light of the growing literature on the overall subject of “endocytobiology.” Emphasized is the complicated network of interactions between symbiotic partners and the importance of the development of integrative mechanisms in the evolution of the many intimate associations known at the cellular level today.

Notes: Long neglected has been the extensive and more or less intimate association of protozoa with a wide variety of other cells, either prokaryotic or eukaryotic in nature. Yet study of such relationships can provide important information concerning certain basic aspects of cellular evolution in general. A survey is offered here of the whole range of such symbiotic associations (i.e. with species of protozoa serving as hosts) with the purposes of drawing attention to the exciting possibilities of such research and of reviewing significant findings made to date. Because of the vastness of the overall field, examples and discussion are primarily limited to consideration of the following major studies: methanogenic bacteria in certain ciliates, bacterial endosymbionts of the large freshwater amoeba Pelomyxa palustris (itself an amazing organism from an evolutionary/phylogenetic point of view), the rod-shaped bacteria found in Amoeba proteus, the “Greek-letter” prokaryotes of Paramecium species, the xenosomes (sensu stricto) of the marine scuticociliate Parauronema acutum, and the diverse algal endosymbionts of similarly diverse protozoan taxa–ciliates, flagellates, radiolarians, acantharians, and foraminifera.

Notes: Soil is the focus of organic matter turnover in terrestrial ecosystems and is an interstitial mosaic of microsites composed of particle aggregates and pore spaces, where transformation, decomposition, mineralization, and humification of organic matter takes place. Microorganisms and animals are scattered discontinuously in these microsites. Microarthropods and larger fauna increase the rate and amount of mineralization by comminution of organic matter and by redistribution of microsites through movements of earthworms and large arthropods; however, mineralization and return of nutrients to plants occurs in the community of bacteria, fungi, protozoa, and nematodes living in the water films covering aggregates and filling pore spaces. Protozoa, especially small amoebae, are important bacterial grazers because they can enter tiny spaces unavailable to nematodes. The latter graze bacteria, fungi, and protozoa. Protozoan and nematode predation increase the amounts of soluble nutrients and decrease the competitive abilities of bacteria, thus making these nutrients more available to plants. Protozoa enhance nutrient recycling out of proportion to their biomass.

Notes: Following conjugation of the hypotrichous ciliate Euplotes aediculatus, the posterior fragments of the old (prezygotic) macronucleus persist until after the first vegetative division. These fragments remain viable during exconjugant development as shown by their ability to regenerate should the cell's new macronucleus be damaged. It thus seemed possible that these parental nuclear fragments might participate in the development of the new macronucleus and/or the crucial post-conjugant cortical reorganization that restores the exconjugant cell's ability to feed. This idea was tested by damaging the posterior fragments with various doses of microbeam ultraviolet (UV) light and assessing the results of such treatment on subsequent cortical and nuclear development. When the posterior fragments of the macronucleus were irradiated at the beginning of cortical morphogenesis, the new macronucleus in 1/3 to 1/2 of the cells assumed a “folded” appearance but did not mature. These cells did not undergo cortical reorganization. Cells irradiated at earlier stages did not detectably develop an oral apparatus; their new macronucleus remained arrested at the spherical anlage stage. The results show that the posterior fragments of the parental macronucleus are necessary for normal nuclear and cortical development. These old nuclear fragments appear to influence the growing macronuclear anlage directly and probably the cortex as well. There also appears to be an information flow from the non-irradiated partner of a persistently joined exconjugant doublet to its irradiated counterpart, enabling normal anlage and cortex development in the irradiated cell.

Notes: Envelope development in Trachelomonas lefevrei (Deflandre) begins with the production of short, coarse mucilaginous strands, morphologically similar to the mucilage produced by non-enveloped euglenoids. These initial mucilaginous secretions subsequently become impregnated with manganese (Mn) and/or iron (Fe). Continued mucilage secretion and mineralization results in a mature envelope that is characteristic for the species. When these mature envelopes are treated with oxalic acid to remove the Mn and Fe, the envelopes collapse and are composed only of short, coarse mucilaginous strands similar to those present during early stages of development, prior to their mineralization. Brief treatment with 10 mM EDTA renders dark envelopes colorless, and our EM-EDS analyses show that this corresponds to a loss of Mn from the envelope; however, if Fe is present in the envelope, it is unaffected by the brief treatment. The mucilage present during early stages of envelope development and that remaining after complete demineralization is also morphologically similar to the mucilage in the plug at the anterior end of the envelope.

Notes: . Micronuclear mitosis in living Spirostomum teres has been studied by sensitive polarization microscopy, and the dynamic aspects of micronuclear division are described. The small, spherical, interphase micronuclei lie in form-fitting depressions in the macronuclear surface. Nuclear division begins with the rounding and slight swelling of the macronucleus and, coincidentally, the micronuclei move out of the depressions and away from the macronucleus, increase in size, and become weakly birefringent. As mitosis proceeds, the micronuclei increase in uniaxial birefringence and elongate to form irregular ovoids that convert to angular structures displaying principal axes of positive birefringence so divergent as to appear oriented at a right angle to one another. Micronuclei maintain this appearance for as long as 60 min and then abruptly change to rectangular-shaped structures, increase in uniaxial birefringence, and begin anaphase elongation. The somewhat dumbbell-shaped micronuclei lengthen at the constant rate of 2.0 μm/min to reach lengths 〉70 μm. It appears that little half-spindle shortening occurs during spindle elongation. Accompanying the changes in micronuclear spindle length are changes in birefringence. Just before elongation begins, presumably metaphase, the micronucleus is uniformly and intensely birefringent. At the magnifications employed, a chromosome plate is not clearly visible as a region of reduced birefringence. As elongation begins, the putative half-spindles are more birefringent than is the interzone, a condition that is maintained until the spindles have achieved ∼30% elongation, at which time a region of increased birefringence develops at the center of the interzone. This pattern persists for a very short time, then gives way to a uniform birefringence of the entire separation spindle that is maintained until elongation is completed. The rate of micronuclear spindle elongation, changes in micronuclear dimensions, and corresponding changes in birefringence are discussed with respect to possible mechanisms of mitosis.

Notes: Two new species of the genus Nosema (Microsporida: Nosematidae) are described from the Mexican bean beetle, Epilachna varivestis (Coleoptera: Coccinellidae) and their life cycle stages studied by light and electron microscopy. Both species are monomorphic and disporous: they develop in direct contact with the cytoplasm of host cells and the nuclei of all stages are diplokaryotic. The more virulent species produces systemic infections most extensively in the adipose tissue, muscles, and Malpighian tubules of larvae and also invades the reproductive tissues of adult beetles. During merogonic development, it forms chains of diplokaryotic meronts. The fine structure of the sporoblast nuclei shows clumped material in the pole of each nucleus opposite their common plane of apposition. Spores are straight to slightly curved and ovocylindrical in shape and they measure 5.3 ± 0.13 × 2.1 ± 0.03 μm. The less virulent species also invades most host tissues but does not develop in the midgut epithelium; the Malpighian tubules are the principal site of its development and it also invades the ovaries and testes of adult beetles. Merogony occurs exclusively as the result of binary fission of diplokaryotic meronts. The plasmalemma of the meronts is covered with a thin deposit of exospore material upon which are located closely packed tubules that encircle the body transversely. A thickened deposit of exospore material on the surface of the diplokaryotic sporonts later obscures these tubules. Other tubules occur free in the host cell cytoplasm or attached to the plasmalemma of meronts and sporonts. Secretory granules also occur free or in chains in the host cytoplasm and are probably produced from the surface of the sporoblasts. Sporoblasts also contain an unusual cup-shaped organelle associated with a dense body, which is apparently involved in the formation of the polar tube and its associated organelles in the anterior part of the spore. Spores are ellipsoidal to slightly pyriform and measure 4.7 ± 0.06 × 2.6 ± 0.03 μm.

Notes: Marshall, K. C., ed. 1984. Advances in Microbial Ecology.

Notes: Starved Tetrahymena thermophila (or cells growing in Holz's defined medium) are attracted by a chemosensory response to complex peptide mixtures as proteose peptone, yeast extract, and extracts of blood platelets containing platelet-derived growth factor. Starved cells are also significantly attracted by mixtures of amino acids and of nucleosides of Holz's defined medium; however, no individual amino acid or nucleoside could be identified as the major chemo-attractant.The positive chemosensory response can be abolished by cycloheximide (CHX) but is insensitive to actinomycin D and puromycin, possibly indicating that de novo RNA and protein synthesis are not necessary for a change in chemosensory behavior. Three mutants resistant to CHX show normal response in the presence of the drug.The possible role of peptides as naturally occurring food signals of Tetrahymena is discussed.

Notes: The premeiotic micronucleus of Tetrahymena thermophila elongates parallel to the long axis of the cell. In fixed cells one end of this crescent micronucleus appears thicker than the other, and either end may be oriented toward the anterior of the cell. Three families of repeated DNA sequences have been localized in the crescent micronucleus by in situ hybridization. Two micronucleus-specific sequences hybridize all along the crescent, but preferentially toward the ends. A macronucleus-retained sequence hybridizes preferentially to the half of the micronucleus at the thick end. Thus the arrangement of DNA sequences in the crescent micronucleus is nonrandom.

Notes: Simple culture conditions that allow good growth and high yields of trypomastigotes are described. The proportion of metacyclic trypomastigotes increases with the concentration of hemin in the culture medium, reaching a peak of 80% after 10 days with 20 mg hemin/liter.

Notes: . Studies performed with the basidiomycete Laccaria trullisata collected from the sandy beach at the Hempstead Lake State Park, Long Island, New York, during the growing seasons of 1979 and 1980, have demonstrated a carposphere (equivalent to rhizosphere) effect. This region exerts a positive influence on the population density of amoebae when numbers are compared with those obtained in the bare sand 5 cm away. Moreover, amoebae have been shown to exist in, and have been recovered from, internal tissue of the cap (72%) and stalk (91%) of these mushrooms. A partial characterization of three strains of amoebae isolated from the internal tissue of L. trullisata and established in clonal culture is presented.

Notes: L'étude, par le protargol, des phénomènes infraciliaires et de leur corrélation avec les phénomènes nucléaires au cours de l'autogamie dans le genre Euplotes montre, par comparaison avec la conjugaison, que les diverses étapes de la morphogenèse sont liées à la progression de l'état nucléaire. Par ailleurs, l'étude comparative des différents types de morphogenèse (bipartition, phénomena sexuel, réorganisation induite par le jeǔne) permet de supposer qu'il existe deux territoires morphogènes soumis à des systèmes de régulation bien distincts. La comparaison des séquences de morphogenèse chez divers hypotriches conduit à dresser un plan général d'évolution de la régulation de l'activité corticale en relation avec l'étendue des remaniements associés à la stomatogenèse.〈section xml:id="abs1-2"〉〈title type="main"〉ABSTRACTThe changes in the arrangement of the infraciliature associated with autogamy in Euplotes are described and compared with similar events associated with conjugation. The successive steps of morphogenesis are strongly correlated with nuclear processes. The comparative study of different types of morphogenesis (binary fission, sexual phenomena, starvation-induced reorganization) leads to the hypothesis that two morphogenetic fields (a ventral one and a dorsal one) depend on separate regulatory systems. From the viewpoint of evolution, the morphogenetic sequences of some hypotrichs have been compared. A general scheme of the evolution of cortical regulation is proposed, taking into account the extension of the area concerned with stomatogenic activity.

Notes: Mouse omentum was studied after intraperitoneal challenge with tachyzoites of Toxoplasma gondii. Parasites inhabit omental histiocytes, fibroblasts, mesothelial cells, and free peritoneal macrophages. Recently infected cells showed enhanced metabolic and functional activity. Villous projections of the parasitophorous vacuole wall appeared, usually opposite the anterior pole of the parasite. In mesothelial cells, projections formed terminal swellings not observed in other infected cells. Activation of host cells was followed by reduction of the density of the cytoplasmic matrix, autophagosome formation, and intracellular edema, indicating the damage. The wall of the parasitophorous vacuole loses the supporting host cell endoplasmic reticulum that was attached to the vacuole just after entrance of the parasite into the cell. Then lysis of the parasitophorous vacuole and complete cell destruction occurs. The growth of parasites in undamaged cells does not coincide with the inflammatory response. Inflammation of the peritoneum develops only after the start of mass destruction of infected cells. Thus tachyzoites of Toxoplasma exert significant pathogenic effects by their ability to activate the host cell, causing lysis of the parasitophorous vacuole and subsequent destruction of the entire cell.