Upgrade of the helically symmetric experiment Thomson scattering diagnostic suite

The Helically Symmetric eXperiment (HSX) Thomson Scattering (TS) diagnostic is being upgraded to decrease uncertainty in electron temperature and density measurements. Upgrades to the HSX TS diagnostic will consist of a novel redesign of polychromator electronics and digitization of the TS output signal. Here, we also present a study of the benefits of an additional spectral channel that will sample the red-shifted band of the scattered spectrum. To maximize system bandwidth (BW) and gain, while minimizing noise, the existing low-BW polychromator electronics on HSX will be replaced by high-BW, high gain circuitry designed in-house.

Development of beam emission spectroscopy in the helically symmetric experiment stellarator

This study shows the feasibility of a beam emission spectroscopy (BES) diagnostic in the Helically Symmetric eXperiment (HSX) stellarator for obtaining the spatiotemporal structure of density fluctuation. A beam emission simulation was applied to HSX plasmas to design and optimize viewing chords and to estimate the beam emission spectrum. A Doppler-shifted beam emission spectrum was measured from a 30 kV, 4 A diagnostic neutral beam injected into HSX plasmas. The beam emission was measured with a high-time-resolution avalanche photodiode (APD) assembly to determine the feasibility of BES in HSX. For HSX plasmas heated by 28 GHz electron cyclotron heating, a mode around f = 15 kHz was observed in the BES signal. The coherence between the BES signal and the density fluctuation measured by an interferometer system was significant. A plan for improving the BES system to enable the measurement of higher frequency related to turbulent transport is presented. The array of sightlines proposed in this study can be used to measure beam emission with a Doppler shift larger than 3 nm (blue shift), which enables the use of a wide passband interference filter to obtain higher throughput. The adoption of a large objective optics and a chilled APD assembly will improve the signal-to-noise ratio.

Matrix Isolation Spectroscopy and Nuclear Spin Conversion of Propyne Suspended in Solid Parahydrogen

Parahydrogen (pH₂) quantum solids are excellent matrix isolation hosts for studying the rovibrational dynamics and nuclear spin conversion (NSC) kinetics of molecules containing indistinguishable nuclei with nonzero spin. The relatively slow NSC kinetics of propyne (CH₃CCH) isolated in solid pH₂ is employed as a tool to assign the rovibrational spectrum of propyne in the 600-7000 cm^-1 region. Detailed analyses of a variety of parallel (ΔK = 0) and perpendicular (ΔK=±1) bands of propyne indicate that the end-over-end rotation of propyne is quenched, but K rotation of the methyl group around the C₃ symmetry axis still persists. However, this single-axis K rotation is significantly hindered for propyne trapped in solid pH₂ such that the energies of the K rotational states do not obey simple energy-level expressions. The NSC kinetics of propyne follows first-order reversible kinetics with a 287(7) min effective time constant at 1.7 K. Intensity-intensity correlation plots are used to determine the relative line strengths of individual ortho- and para-propyne rovibrational transitions, enabling an independent estimation of the ground vibrational state effective A″ constant of propyne.

Development of a 3-D visible limiter imaging system for the HSX stellarator

A visible camera diagnostic has been developed to study the Helically Symmetric eXperiment (HSX) limiter plasma interaction. A straight line view from the camera location to the limiter was not possible due to the complex 3D stellarator geometry of HSX, so it was necessary to insert a mirror/lens system into the plasma edge. A custom support structure for this optical system tailored to the HSX geometry was designed and installed. This system holds the optics tube assembly at the required angle for the desired view to both minimize system stress and facilitate robust and repeatable camera positioning. The camera system has been absolutely calibrated and using H_α and C-III filters can provide hydrogen and carbon photon fluxes, which through an S/XB coefficient can be converted into particle fluxes. The resulting measurements have been used to obtain the characteristic penetration length of hydrogen and C-III species. The hydrogen λ_iz value shows reasonable agreement with the value predicted by a 1D penetration length calculation.

A synthetic diagnostic for beam emission spectroscopy in the helically symmetric experiment stellarator

The Helically Symmetric Experiment (HSX) has a number of active spectroscopy diagnostics. Due to the relatively large beam width compared to the plasma minor radius, it is difficult to achieve good spatial resolution at the core of the HSX plasma. This is due to the fact that the optical sightline cuts through many flux surfaces with varying field vectors within the beam. In order to compare the experimental results with theoretical models it is important to accurately model the beam width effects. A synthetic diagnostic has been developed for this purpose. This synthetic diagnostic calculates the effect of spot size and beam width on the measurements of quantities of interest, including radial electric field, flow velocity, and Stark polarization.

Sensitivity of MSE measurements on the beam atomic level population

The effect of variation in atomic level population of a neutral beam on the Motional Stark Effect (MSE) measurements is investigated in the low density plasmas of HSX stellarator. A 30 KeV, 4 A, 3 ms hydrogen diagnostic neutral beam is injected into HSX plasmas of line averaged electron density ranging from 2 to 4 ⋅ 10¹⁸ m^-3 at a magnetic field of 1 T. For this density range, the excited level population of the hydrogen neutral beam is expected to undergo variations. Doppler shifted and Stark split H_α and H_β emissions from the beam are simultaneously measured using two cross-calibrated spectrometers. The emission spectrum is simulated and fit to the experimental measurements and the deviation from a statistically populated beam is investigated.

Energetic-electron-driven instability in the helically symmetric experiment

Energetic electrons generated by electron cyclotron resonance heating are observed to drive instabilities in the quasihelically symmetric stellarator device. The coherent, global fluctuations peak in the plasma core and are measured in the frequency range of 20-120 kHz. Mode propagation is in the diamagnetic drift direction of the driving species. When quasihelical symmetry is broken, the mode is no longer observed. Experimental observations indicate that the unstable mode is acoustic rather than Alfvénic.

Effect of quasihelical symmetry on trapped-electron mode transport in the HSX stellarator

This Letter presents theory-based predictions of anomalous electron thermal transport in the Helically Symmetric eXperiment stellarator, using an axisymmetric trapped-electron mode drift wave model. The model relies on modifications to a tokamak geometry that approximate the quasihelical symmetry in the Helically Symmetric eXperiment (particle trapping and local curvature) and is supported by linear 3D gyrokinetic calculations. Transport simulations predict temperature profiles that agree with experimental profiles outside a normalized minor radius of rho>0.3 and energy confinement times that agree within 10% of measurements. The simulations can reproduce the large measured electron temperatures inside rho<0.3 if an approximation for turbulent transport suppression due to shear in the radial electric field is included.

Experimental demonstration of improved neoclassical transport with quasihelical symmetry

Differences in the electron particle and thermal transport are reported between plasmas produced in a quasihelically symmetric (QHS) magnetic field and a configuration with the symmetry broken. The thermal diffusivity is reduced in the QHS configuration, resulting in higher electron temperatures than in the nonsymmetric configuration for a fixed power input. The density profile in QHS plasmas is centrally peaked, and in the nonsymmetric configuration the core density profile is hollow. The hollow profile is due to neoclassical thermodiffusion, which is reduced in the QHS configuration.

Experimental evidence of reduced plasma flow damping with quasisymmetry

Measurements of plasma flow damping have been made in the helically symmetric experiment using a biased electrode to impulsively spin the plasma. There are two time scales in the evolution of the plasma flow, for both the spin-up and relaxation. Compared to a configuration with the quasisymmetry broken, the flow in the quasisymmetric configuration rises more slowly and to a higher value at bias turn-on, and decays more slowly at bias turn-off. The decays of the flows are significantly faster than the neoclassical prediction.

Mapping the OH + CO-->HOCO reaction pathway through IR spectroscopy of the OH-CO reactant complex

A hydrogen-bonded complex composed of the OH and CO reactants has been identified along the OH + CO-->HOCO reaction pathway. IR action spectroscopy in the OH overtone region has been used to examine the vibrational modes of the linear OH-CO complex, including intermolecular bending modes that probe portions of the reaction path leading to HOCO. The spectroscopic measurements have accessed highly excited intermolecular levels, with energies up to 250 cm-1 above the zero-point level, which lie in close proximity to the transition state for reaction. The OH-CO binding energy, D0 < or = 430 cm-1, has also been established from the quantum state distribution of the OH fragments following vibrational predissociation of the OH-CO complex. Complementary electronic structure calculations have been performed to characterize the OH-CO and OH-OC complexes, the transition state for HOCO formation, and the direct reaction path that connects the experimentally observed OH-CO complex to the HOCO intermediate.

Duragesic transdermal patch: postmortem tissue distribution of fentanyl in 25 cases

Fentanyl is a potent, short-acting narcotic analgesic widely used as a surgical anesthetic and for the control of pain when administered in the form of a transdermal patch. The success of the patch can be attributed to fentanyl's low molecular weight and its highly lipophilic nature, which enables it to be readily absorbed through the skin and subsequently distributed throughout the body. Over the past three years, the Los Angeles County Coroner's Toxicology Laboratory has encountered 25 cases involving Duragesic patches (fentanyl), and their postmortem tissue distributions are presented here. The analysis of fentanyl from postmortem specimens (3-mL or g sample size) consisted of an n-butyl chloride basic extraction followed by identification and quantitation on a gas chromatograph-mass spectrometer using the selected ion monitoring (SIM) mode. The fentanyl ions monitored were m/z 245, 146, and 189 and the internal standard, fentanyl-d5 ions, were m/z 250, 151, and 194 (quantitation ion underlined). The linear range of the assay was 1.67 microg/L to 500 microg/L with the limit of quantitation and detection of 1.67 microg/L. The postmortem tissue distribution ranges of fentanyl in the 25 fatalities were as follows: heart blood, 1.8-139 microg/L (23 cases); femoral blood, 3.1-43 microg/L (13 cases); vitreous, +<2.0-20 microg/L (4 cases); liver, 5.8-613 microg/kg (22 cases); bile, 3.5-262 microg/L (15 cases); urine, 2.9-895 microg/L (19 cases); gastric, 0-1200 microg total (17 cases); spleen, 7.8-79 microg/kg (3 cases); kidney, 11 microg/kg (1 case); and lung, 31 microg/kg (1 case). The age of the decedents in this study ranged from 19 to 84, with an average age of 46. The modes of death included 15 accidental, 5 natural, 3 suicidal, and 2 undetermined. The main objectives of this paper are to show the prevalence of fentanyl patches in our community and to aid the forensic toxicologist with the interpretation of postmortem fentanyl levels in casework.

Quetiapine (Seroquel) concentrations in seven postmortem cases

Quetiapine is a new antipsychotic drug that has been available in the United States since September 1997. It belongs to a new chemical class of drugs called the dibenzothiazepine derivatives and is easily detected with a basic drug screen. The Los Angeles County Department of Coroner Toxicology Laboratory has encountered quetiapine in seven postmortem cases. Tissue distributions were determined in each of the seven cases. The analysis of quetiapine from postmortem specimens consisted of an n-butylchloride basic extraction with presumptive identification and quantitation on a gas chromatograph-nitrogen-phosphorus detector. Linearity was achieved from 0.10 to 3.0 mg/L with a limit of quantitation of 0.10 mg/L. Confirmation of quetiapine was performed on a gas chromatograph-mass spectrometer by comparison with a pure analytical standard. The tissue distribution of quetiapine was as follows: heart blood present, but less than (+<) 0.10-49 mg/L (seven cases); femoral blood +< 0.10-1.4 mg/L (five cases); liver +< 0.10-112 mg/kg (five cases); spleen 4.0 mg/kg (one case); urine 0-3.0 mg/L (two cases); bile 0.60-7.5 mg/L (three cases); and gastric contents +< 0.01-18 mg total (five cases). To our knowledge, this is the first report of the presence of quetiapine in postmortem specimens.

Distribution of mirtazapine (Remeron) in thirteen postmortem cases

Mirtazapine is a new antidepressant agent that entered the United States market in April 1996. To date, the literature provides limited information about therapeutic blood concentrations and virtually no information about postmortem levels. The Los Angeles County Coroner's Toxicology Laboratory has encountered 13 cases where postmortem tissue distributions of mirtazapine were determined. The analysis of mirtazapine from postmortem specimens (2-mL sample size) consisted of an n-butylchloride basic extraction procedure with identification and quantitation on a gas chromatograph-nitrogen-phosphorus detector. Linearity was achieved from 0.025 mg/L to 3.0 mg/L with a limit of quantitation of 0.025 mg/L. Confirmation of mirtazapine was performed on a gas chromatograph-mass spectrometer by comparison with a pure analytical standard. The tissue distribution of mirtazapine are in the following concentration ranges: heart blood 0.03-0.57 mg/L (13 cases), femoral blood 0.04-0.24 mg/L (9 cases), vitreous 0.06-0.10 mg/L (3 cases), liver 0.32-2.1 mg/kg (12 cases), bile 0.40-6.6 mg/L (7 cases), urine 0.12-2.5 mg/L (11 cases), kidney 0.23 mg/kg (1 case), spleen 0.17 mg/kg (1 case), and gastric 0.001-2.7 mg total (9 cases). Mirtazapine was not implicated in the cause of death in any of the 13 cases studied. These cases are being presented to aid the forensic toxicologist in the evaluation of postmortem mirtazapine levels.

Fatal flecainide intoxication

Two fatalities resulting from suicidal ingestion of flecainide are described. The decedents, ages 33 and 15, were otherwise healthy; both took their mothers' medications. In one case, from electrocardiographic data, there was found a high-grade conduction block with idioventricular rhythm. Blood and tissue samples from autopsy were analyzed for flecainide by gas chromatography/nitrogen-phosphorous detection and gas chromatography/mass spectrometry. Blood concentrations of 93.7 and 100 mg/L flecainide were found.

Genetic markers in human bone: I. Deoxyribonucleic acid (DNA) analysis

Deoxyribonucleic acid (DNA) was isolated from a number of spongy and compact human bone tissue specimens, and the yield was estimated on a "per milligram of starting tissue" basis. DNA was, in addition, isolated from a number of corresponding blood and bone tissue specimens. Spectrophotofluorometry and ethidium bromide visualization on minigels were used to estimate the quantity and degree of degradation of DNA. The DNA from several blood-bone pairs is shown to give concordant restriction fragment length polymorphism (RFLP) typing results by two different typing protocols with five different single-locus probes. DNA from several additional blood-bone pairs is shown to give concordant results for human leucocyte antigen (HLA)-DQ alpha phenotypes following polymerase chain reaction (PCR) amplification and hybridization to specific allele-specific oligonucleotide (ASO) probes, and for the variable numbers of tandem repeats (VNTR) length polymorphisms 3' to the human apolipoprotein B (APOB) gene following PCR amplification with specific primers and analysis of the products by electrophoresis and ethidium bromide visualization.

Reproduction and development of the spider Nephila edulis (Koch) (Araneidae : Araneae)

The sexually dimorphic Nephila edulis breeds during the autumn (February-May), the large female producing one egg-sac per season, containing an average of 383 eggs. The web of immature females sometimes incorporates a stabilamentum. Mating behaviour can result in the death of the male and is different from the ritualized mating behaviour of N. maculata. The male of N. edulis always begins its mating sequence after a female has caught prey. N. edulis in the study site fed predominantly on leafhoppers, dealing with its prey by a stereotyped attack sequence. The egg-mass of N. edulis is laid in a complex egg-sac of yellow silk. Each 1.14-mm diameter egg is coated with minute, regular particles which may have water-resistant properties. The prehatching development time is long; 29 days at 20�C and 42-87 days in the field. The external embryonic stages are similar to those of other araneomorph spiders. Pigmentation, developed in embryos of N. edulis after the germ band stage, is believed to be associated with the breakdown of yolk. The external changes during the first three posthatching instars are described. The emergence from the egg-sac at the third instar is correlated with the depletion of yolk reserves at this stage. The function of the egg-sac of N. edulis is not related to protection from extremes of temperature or humidity. The function is discussed in relation to protection of the eggs from predators and parasites.

The reproductive system, embryonic development, larval development and metamorphosis of the sea urchin Heliocidaris erythrogramma (Val.) (Echinoidea : Echinometridae)

H. erythrogramma has an annual reproductive cycle, spawning asynchronously. The female cycle has five phases: resting, regenerating, mature, spent and regressing; the male cycle omits the regression phase. Regression and resting occur only during April-August; regeneration begins in September; during December-March individual urchins pass through the mature, spent and regenerating phases two or three times. The egg averages 400 �m diameter and floats at the water surface. At 24-25�C, equal, total, radial cleavage yields a wrinkled coeloblastula by 6-7 hours; this undergoes egression, becoming a spherical stereoblastula by 13-14 hours; during this process an acellular central yolk mass is segregated from a peripheral columnar blastoderm. The ciliated stereoblastula gastrulates by a typical diphasic invagination, beginning at 15 hours, and the gastrulating embryo hatches as a ciliated, planktonic yolk-larva at 15-16 hours. Lecithotrophic development of the yolk-larva to a uniformly ciliated, planktonic vitellaria is complete by 1.5 days, and the larva metamorphoses gradually to a lecithotrophic juvenile over the next 3.5 days. It remains planktonic during the first half of this period (to 3.75 days), but settles during the second half (to 5 days). The juvenile begins to feed >3 weeks after settling. Vegetally proliferating mesenchyme invades the yolk mass during gastrulation. Invagination of the archenteron is followed by evagination of a primary pair of coelomic pouches from its wall; the left enterocoel forms the hydrocoel. Other coelomic cavities are re-formed by schizocoely. The larval gut rudiment temporarily loses connection with the exterior after the blastopore closes. The proctodaeum and stomodaeum of the juvenile form secondarily during and after metamorphosis. Ectodermal development of the echinus rudiment, though gradual, is typical of echinoids. The blastulation of H. evythrogramma is unique among large-egged echinoderms in combining egression of a wrinkled coeloblastula with segregation of a blastoderm around a central yolk mass. The development of the species supports the view that the vitellaria larva is secondarily evolved within the Echinoidea.

The morphological basis of embryonic movements in the light brown apple moth, Epiphyas postvittana (Walk) (Lepidoptera : Tortricidae)

A description is given of the morphological basis of the embryonic movements revealed in E. postvittana by time-lapse cinematography. The blastoderm gives rise to a broad germ band and serosal rudiment. The serosa spreads over the germ band, followed by the amnion. The germ band becomes cup-shaped, elongates, and turns on its side in the flattened egg before gastrulation begins. Only a small amount of the yolk of the egg is enclosed in the germ band. The remainder fills the amnioserosal space. As elongation continues, mainly through growth in the length of the abdomen, and segmentation takes place, the germ band becomes spirally coiled and convoluted within the flattened egg space. At the completion of elongation, the nervous system is well developed, segmental myoblasts are present, and the tubular stomodaeum and proctodaeum are linked by paired midgut strands. Shortening and dorsal closure eliminate the spiralling and convolution of the germ band and result in a tubular embryo with a large ganglionated nerve cord and large stomodaeum and proctodaeum, but with musculature still at the myoblast stage and midgut strands unchanged. Paired sheets of cardioblasts extending from the body wall to the midgut strands divide the ventral haemocoele from the dorsal haemocoele in the middle region of the body. A mesodermal sac covers the inner end of the stomodaeum and opens in the dorsal haemocoele. The tubular embryo now elongates, doubling its volume, reverses its position in the egg, and tucks the tail in beside the head. During elongation, the segmental myoblasts differentiate as muscle fibres. Towards the end of elongation and reversal, the midgut strands give rise to the midgut tube and the cardioblast sheets to the middorsal heart. When elongation and reversal are complete, the stomodaeal mesodermal sac is transformed into proventricular mesoderm. After further differentiation of striated muscle and secretion of the cuticle, the embryo ingests the yolk in the surrounding amnioserosal space and digests it before hatching takes place. Comparison of morphological structure with the movements displayed in the time-lapse record show that all elongation, rotation, spiralling, and convolution of the embryo before the onset of shortening is due to growth by cell proliferation and to accommodation of this growth within a fixed egg space of specific shape. In contrast, controlled muscular activity plays a major role in shortening and dorsal closure, in elongation and reversal of position, and in ingestion of excluded yolk. During shortening and dorsal closure, slow, generalized, possibly myogenic contractions are produced by the somatic myoblasts and appear to be responsible for the shape changes observed. During elongation and reversal, contractions are confined to the stomodaeal myoblast layer and result in rhythmic filling and emptying of the terminal stomodaeal sac. By this activity, fluid is transferred from the excluded yolk to the embryo and pumped along the dorsal haemocoelic channel, bringing about controlled elongation and reversal. In view of the coordination exhibited, and of the precocious development of the nervous system, it seems likely that this activity is neurogenic, even though the contractile units are still myoblasts. The final movement of reversal, tucking in of the tail, is due to somatic musculature, now differentiated as muscle fibres and showing twitches of probably neurogenic causation. Ingestion of excluded yolk is a precocious feeding activity, brought about by coordinated action of the larval feeding apparatus, and occurs only when the appropriate musculature has become differentiated as striated muscle. Although the morphogenetic movements of E. postvittana show modifications associated with the flattened form of the egg, they and their structural basis are, on comparative evidence, common to all lepidopteran embryos.

Larval development and segment formation in the branchipod crustaceans Limnadia stanleyana King (Conchostraca) and Artemia salina (L.) (Anostraca)

Limnadia stanleyana hatches as a lecithotrophic nauplius with a well-developed naupliar region and a globular post-naupliar region, the latter comprising the rudiments of 10 post-mandibular segments, a growth zone, and a telson. Development proceeds through five naupliar stages. Feeding begins late in stage III. Action of a naupliar feeding apparatus sustains the larva through stages IV and V. During these stages, the maxillulary and maxillary segments, the carapace, and the first six trunk segments become well developed. At the fifth moult, metamorphosis occurs to a juvenile conchostracan. The naupliar feeding apparatus is lost, the first six pairs of trunk limbs become functional, and feeding in the adult manner begins. The seventh and succeeding trunk segments are delayed in development. In the development of postmandibular segments, mesodermal somite segregation precedes ectodermal segment delineation. Post-mandibular segments behind the tenth are proliferated by a growth zone comprising an external ring of ectoderm and paired lateral rows of mesoteloblasts. Artemia salina hatches as a nauplius similar to that of L. stanleyana, and develops in an identical manner through the first four naupliar stages. The larval development of L. stanleyana is typical of Conchostraca. The larval development of A. salina is typical of Anostraca and differs from that of L. stanleyana only in passing through nine naupliar stages before metamorphosis. The larval development of the Notostraca differs from that of Conchostraca and Anostraca only in ways related to increased lecithotrophy, metamorphosis being attained more directly. A primitive mode of development can be identified for the Branchiopoda and interpreted as a derived form of the developmental pattern of the Cephalocarida. Sanders' hypothesis of a cephalocaridan-like ancestry of the Branchiopoda is upheld by the evidence of development. Post-mandibular segment formation in branchiopods remains primitive, and lacks the specializations found in Cirripedia and Malacostraca. Segment formation cannot be employed as a criterion of phylogenetic affinity in Crustacea.

Embryonic and larval development and segment formation in Ibla quadrivalivis Cuv. (Cirripedia)

Embryonic development in I. quadrivalvis follows the typical cirripede pattern except for modifications of cleavage and of development of the gut, associated with a large yolky egg. The nauplius is free-swimming but lecithotrophic. It does not grow, and moults irregularly. The development of cypris features begins precociously and the second half of naupliar life is demersal. The cypris stage is unmodified. Settling was not observed. The maxillary segments develop as a delayed continuation of the naupliar segmental sequence, the thoracic segments from a growth zone of seven ectoteloblasts and eight mesoteloblasts. Each row of eight cells budded from the mesoteloblasts develops into the paired somites of a segment. The midgut develops independently of the yolk cells. In cirripedes, increased yolk results in modification of cleavage and gut development but otherwise has little influence on embryonic development. Larval modifications associated with lecithotrophy promote direct development of the cypris but do not include modification of the cypris. Irregularity of moulting is associated with lack of larval growth. Relative brood sizes suggest that increased yolk in cirripedes offers advantages in larval survival. Post-naupliar segment formation in cirripedes resembles in detail that of Malacostraca, indicating a possible phylogenetic affinity between Malacostraca and Maxillopoda which can be tested by further studies on segment formation in non- Malacostraca.

Oogenesis in Dacus tryoni (Frogg.) (Diptera: Trypetidae)

Oogenesis in D. tryoni is typical of cyclorrhaphous Diptera. The ovariolar germarium produces a linear succession of 16-cell cysts enclosed by follicle cells. The cells of a cyst are interconnected by cytoplasmic canals and differentiate as 15 nurse cells and a posterior oocyte. Previtellogenesis occupies 3 days, vitellogenesis 1 day. The oocyte grows slowly during previtellogenesis, with little differentiation, rapidly during vitellogenesis, when protein and fatty yolk deposition, axial differentiation, and nuclear breakdown to first maturation metaphase, take place. The nurse cells grow rapidly during previtellogenesis and early vitellogenesis, developing large polytene nuclei and RNA-rich cytoplasm, and pour an RNA-rich nutrient stream into the oocyte during early vitellogenesis. The stream also contains P.A.S.-positive material, lipid droplets, possibly protein precursors, and nucleotides. Later, the nurse cells degenerate. Both growth and degeneration of the nurse cells are polarized, the posterior cells leading the more anterior cells. The follicular epithelium, cuboidal during previtellogenesis, differentiates as columnar around the oocyte, squamous outside the nurse cells, and anteriorly as border cells which migrate between the nurse cells to the anterior end of the oocyte. Late in vitellogenesis, the follicular epithelium secretes the chorion and vitelline membrane. It is not yet possible to discern in oogenesis the establishment in the oocyte of the prepattern essential for normal epigenesis.

The embryology of Dacus tryoni (Diptera). 3. Origins of imaginal rudiments other than the principal discs

In addition to the principal imaginal discs (cephalic, labial, wing, haltere, leg and genital), the larva in Cyclorrhapha carries as discrete components the rudiments of the imaginal segmental abdominal hypodermis, salivary glands, fore-, mid- and hind-gut, lateral cerebral ganglia and segmental tracheal system (Snodgrass, 1924; Bodenstein, 1950; Shatoury, 1956b; Anderson, 1964, etc.). The embryonic origins of these rudiments have never been firmly established. The present paper describes their origins in the embryo and larva of Dacus tryoni (Frogg.) (Trypetidae), taking a further step in the elucidation of the developmental relationship between the cyclorrhaphan larva and adult.

Material and Methods The embryonic origins of the rudiments in question were traced in serial sections of embryos and larvae prepared by the methods described by Anderson (1962a, 1963b). The reader is referred to these papers for details of the methods employed.

The larval development of Dacus tryoni (Frogg.) (Diptera: Trypetidae). 2. Development of imaginal rudiments other than the principal discs

In D. tryoni, imaginal rudiments of the abdominal hypodermis, of the salivary gland, of the fore-, mid-, and hindgut, of the lateral cerebral ganglia, and of the tracheae, all of which are present as discrete components in the larva, grow by cell multiplication up to the time of puparium formation in the manner generally accepted for Cyclorrhapha. There is no indication in D. tryoni of the epigenetic relationship between lymph glands, haemocytes, and imaginal rudiments postulated for the larva of Drosophila melanogaster by el-Shatoury and Waddington.

The Embryology of Dacus tryoni 2. Development of lmaginal Discs in the Embryo

The cephalic, labial, wing, haltere, leg and genital imaginal discs of Cyclorrhapha are histologically distinct in the late embryo or early larva (Weismann, 1864; Pratt, 1900; Auerbach, 1936; Kaliss, 1939; Poulson, 1950). Experimental investigation of Drosophila melanogaster further suggests that the determined rudiments of the discs are present in the blastoderm of the early embryo (e.g. Geigy, 1932; Howland and Child, 1935; Howland, 1941; Gloor, 1947). Almost no attempt has been made, however, to describe the embryonic origins of the discs or to follow their development before hatching. Investigation of this matter in Dacus tryoni (Frogg) (Diptera, Trypetidae) has clarified the developmental relationship between the cyclorrhaphan larva and adult.

The origin and development of imaginal discs in the embryo of D. tryoni was followed from serial sections prepared in connection with a previous paper (Anderson, 1962). Living embryos were also further examined by the method given in that account.

The larval development of Dacus tryoni (Frogg,) (Diptera : Trypetidae) 1. larval instars, Imaginal discs, and haemocytes

In D. tryoni three larval instars occur, distinguishable by their mouth hooks and anterior and posterior spiracles. In the first two instars, the imaginal discs established during embryonic development grow slowly, only the cephalic discs showing marked change. Paired labial and lateral genital discs invaginate during the second half of the 2nd instar. During the 3rd instar, the imaginal discs increase further in size, first rapidly, then more slowly. Each shows attenuation of the lateral wall as a peripodial membrane, thickening and folding of the median wall without histodifferentiation and, in the wing, haltere, leg, and genital discs, formation of mesoderm from cells in the outer part of the median wall. Disc morphogenesis is largely completed by 120 hr after hatching. A single pair of lymph glands and 13-15 pairs of pericardial cells lie along the heart. Both show cell enlargement during larval life but no proliferation. Haemocytes in the blood arise directly from embryonic mesoderm as two main types, numerous spheroids and less numerous hexagons. They circulate freely in the living larva, but tend to occur in irregular clumps in fixed material, especially after 120 hr. No epigenetic relationship between haemocytes, imaginal discs, and lymph glands such as that described for Drosophila melanogaster by el-Shatoury and Waddington can be discerned in D. tryoni. The haemocytes do not arise from the lymph glands. The disc mesoderm does not arise from the haemocytes. The larval development of the discs is largely completed before the haemocytes become numerous.

The Embryology of Dacus tryoni (Frogg.) [Diptera, Trypetidae (= Tephritidae)], the Queensland Fruit-Fly

The embryology of the Diptera has been investigated in only a few species and of these, only Drosophila melanogaster and Calliphora erythrocephala have been studied in detail. Fragmentary information is available for 17 species of Nematocera, several further species of acalyptrate Cyclorrhapha (all Drosophila species), 6 further species of calyptrate Cyclorrhapha, and 2 species of pupiparous Cyclorrhapha, but little attempt has been made to compare one with another. The present description of the embryology of the larva of the acalyptrate Dacus tryoni, the first of a member of the Tephritidae, provides new data on which a comparative survey of the embryology of dipteran larvae can be based.

Material for this study was supplied by Dr. M. A. Bateman of the Joint Unit of Animal Ecology in the Department of Zoology, University of Sydney, from his laboratory stocks. Rearing of D. tryoni in the laboratory has been fully described by Bateman (1958) and only a brief outline will be presented here.