ULTRASTRUCTURE OF POLAR LOBES IN EGGS OF THE FRESHWATER PROSOBRANCH GASTROPOD AMNICOLA LIMOSA

The structure of polar lobes in eggs of the freshwater prosobranchgastropod Amnicola limosa has been studied by light microscopyand by transmission electron microscopy. A cytoplasmic localization,discovered within the lobes, is described. Its morphology andsubsequent pattern of dispersal are similar to that of the vegetalbody in the polar lobes of Bithynia tentaculata. (Received 12 January 1982;     

THE MORPHOLOGY OF THE OSPHRADIUM IN RELATION TO FEEDING HABITS IN MESO- AND NEOGASTROPODS

The morphology of the osphradium in nine species of meso- andneogastropods was examined using scanning electron microscopy.Herbivores and detritivores (Littorina, Aporrhais) have simpleosphradia consisting of long ridges, covered in ciliary tufts,and flanked on either side by bands of densely ciliated epithelium.Another herbivore Rhinoclavis has the central ridge dividedinto lobes. In carnivorous and predatory species (Polinices,Cypraea, Nucella, Nassarius, and Conus) the osphradium is shorter,larger and divided bi- or triserially, into leaflets. Conusstri-atus which feeds upon the most mobile and least predictableprey (fish) has the largest and most elaborate osphradium, withthe leaflets divided into digitiform processes. The sedentary,ciliary-feeding, Crepidula is anomalous in having an osphradiumdivided into leaflets, although these are vestigial along oneside.     

The brain structure of selected trypanorhynch tapeworms

The brain architecture in four species of tapeworms from the order Trypanorhyncha has been studied. In all species, the brain consists of paired anterior and lateral lobes, and an unpaired central lobe. The anterior lobes connect by dorsal and ventral semicircular commissures; the central and lateral lobes connect by a median and an X-shaped crisscross commissure. In the center of the brain, five well-developed compact neuropils are present. The brain occupies a medial position in the scolex pars bothrialis. The ventral excretory vessels are situated outside the lateral lobes of the brain; the dorsal excretory vessels are located inside the brain and dorsal to the median commissure. The brain gives rize four anterior proboscis nerves and four posterior bulbar nerves with myelinated giant axons (GAs). The cell bodies of the GAs are located within the X-commissure and in the bulbar nerves. Highly developed serotonergic neuropils are present in the anterior and lateral lobes; numerous 5-HT neurons are found in the brain lobes including the central unpaired lobe. The X-cross commissure consists of the α-tub-immunoreactive and 5-HT-IR neurites. Eight ultrastructural types of neurons were found in the brain of the three species investigated. In addition, different types of synapses were present in the neuropils. Glial cells ensheath the brain lobes, the neuropils, the GAs, and the bulbar nerves. Glia cell processes form complex branching patterns of thin cytoplasmic sheets sandwiched between adjacent neural processes and filling the space between neurons. Multilayer myelin-like envelopes and a mesaxon-like structure have been found in Trypanorhyncha nervous system. We compared the brain architecture of Trypanorhyncha with that of an early basal cestode taxon, that is, Diphyllobothriidea, and present a hypothesis about the homology of the anterior brain lobes in order Trypanorhyncha; and the lateral lobes and median commissure are homologous brain structures within Eucestoda.     

THE INNERVATION AND PHYSIOLOGY OF THE EXTRINSIC BUCCAL RETRACTOR MUSCLES OF PHILINE APERTA (LINNAEUS)

Two buccal mass retractor muscles of Philine are innervatedby at least 4 excitatory motoneurons, whose cell bodies liein the buccal and the cerebral ganglia. The muscle fibres respondto action potentials generated in the motoneurons or their axonswith excitatory junction potentials (ejps), each of which isfollowed by a small twitch-like contraction. Both the electricaland mechanical responses facilitate and summate with repetitivestimulation. A large ventrally located cerebral neuron (VGC) inhibits tensiondevelopment in the muscle by reducing the amplitude of the excitatoryjunction potentials from and identified buccal motoneuron. Acetylcholinereversibly depolarises and causes tonic contraction of the muscles.This action is partially antagonised by hexamethonium, whichalso blocks the ejps from two axons in the buccal and one inthe pedal nerve 9. 5-Hydroxytryptamine potentiates the ejp fromthe identified buccal motoneuron and enhances the rate of relaxation.Histamine reduces the amplitude of the presumed cholinergicbuccal nerve ejps, but does not affect the hexamethonium sensitiveejp in the pedal nerve 9. In this respect its action resemblesthat of the ventral giant cell.     

FOUR NEW SPECIES OF TAMBJA BURN, 1962 (NUDIBRANCHIA: POLYCERIDAE) FROM THE INDO-PACIFIC

The genus Tambja previously included 24 described species. Fournew species, T. tentaculata n. sp., T. gabrielae n. sp., T.zulu n. sp. and Tambja victoriae n. sp., from the Indo-Pacificare described. Tambja tentaculata n. sp., from Guam, is theonly known species in the genus with well developed, dorsolaterallygrooved, oral tentacles. Its inner lateral teeth have a bifidinner cusp with two long, sharp denticles. The oral tentaclesof T. tentaculata are more typical of Roboastra species, whilethe shape of the inner lateral teeth is more typical of Tambja.Nevertheless, the arrangement of the two cusps of the innerlateral teeth and the presence of a rachidian tooth withoutdenticles and with a central notch at the anterior edge, typicalof the species of the genus Tambja, suggest the placement withinthis genus. Tambja gabrielae n. sp., from Indonesia and PapuaNew Guinea, has dark green to dark brown ground colour withbright yellow patches scattered on the body. Tambja zulu n.sp. from Durban, South Africa, is characterized by a black groundcolour with slender yellow longitudinal lines. Tambja victoriaen. sp. is a new species from Papua New Guinea and Australiathat has frequently been misidentified as Roboastra arika, characterizedby its blue body colour and yellow lines. The four species aredistinguishable based on differences in body coloration, ofcharacters of the radula and of the reproductive system. Anoverview on distinguishing features of all known Indo-PacificTambja species is presented. (Received 21 June 2004; accepted 20 January 2005)     

Leaf Nucleic Acids:: II. METABOLISM DURING SENESCENCE AND THE EFFECT OF KINETIN

The nucleic acids in the green and in the senescent leaves ofthree types of plant have been studied. High and low molecularweight RNA of the chloroplast is not present in senescent leavesof Xanthium pensylvanicum, but both cytoplasmic and chloroplasticfractions are found in yellow leaves of Vicia faba and Nicotianatabacum. RNA is more rapidly degraded than DNA in the leavesof these plants when they are detached, and kinetin treatmenttemporarily arrests the loss of chlorophyll and nucleic acid.Once X. pensylvanicum leaves are yellow and senescent they cannotbe re-greened, whereas those of Nicotiana spp., and to someextent those of V. faba, can be rejuvenated. We suggest thatthe retention of chloroplast RNA in yellow leaves may be a majorfactor determining their ability to re-green and that the patternof organelle senescence prior to the first stages of leaf autolysisand dehydration is species-specific.     

SOME ABNORMAL FLOWERS OF ARGEMONE MEXICANA AND THEIR BEARING ON THE MORPHOLOGY OF THE GYNOECIUM OF PAPAVERACEAE

Abnormal flowers of Argemone mexicana are described in whichthe gynoecium has been transformed into a cup with lobed marginor into free leafy carpels. The number of lobes or leafy carpelsin such gynoecia is found to vary from three to five. This agreeswith the general view of systematists regarding the number ofcarpels composing the gynoecium in this species, and is againstthe views of Saunders and Dickson who postulate twice as manycarpels.     

EXTRA-CAPSULAR YOLK BODIES IN THE EGG MASSES OF SOME TROPICAL OPISTHOBRANCHIA

Seventeen species of opisthobranch molluscs from Enewetak, MarshallIslands were found to deposit bodies of yolk within their gelatinousegg masses external to the capsules which surround the ova.These observations bring the total number of opisthobranch speciesin which extra-capsular yolk is known to 26. This study reviewsprevious reports of extra-capsular yolk and contributes newdata on the egg masses and developmental characteristics ofspecies in which it is known to occur. The various types ofyolk body found are detailed and categorized, and original observationson the deposition of yolk bodies and their fate during, andsubsequent to embryonic development presented. To date, extra-capsular yolk bodies have been found only withinthe egg masses of species of Chromodoris and Cadlinella (Nudibranchia:Chromodorididae), Elysia (Sacoglossa: Elysiidae), and Bosellia(Sacoglossa: Polybranchiidae). Three types of yolk body arerecognized: (1) cap-like yolk bodies associated with individualcapsules, (2) discrete yolk bodies strewn throughout the eggmass, and (3) continuous or discontinuous yolk strings. Direct consumption of yolk bodies by newlyhatched veligers ofChromodoris albopunctatus (Garrett) is described. In most otherspecies, the yolk disappears during the course of developmentand is probably of nutritive value to the embryos. The availabledata suggest that chromodorid species which utilize extra-capsularyolk during the course of development produce relatively largerlarvae than species with comparably sized ova that do not. (Received 25 November 1982;     

FINE STRUCTURE OF THE NEUROHYPOPHYSIS OF THE OPOSSUM (DIDELPHIS VIRGINIANA)

The neurohypophysis of the opossum (Didelphis virginiana) was studied by electron microscopy in order to amplify Bodian''s classic light microscopic observations in which he demonstrated a definite lobular pattern. The lobule of the opossum neurohypophysis is divided into three regions: a hilar, a palisade, and a septal zone. The hilar portion contains bundles of nerve fibers, the extensions of the hypothalamo-hypophyseal tract containing neurofilaments but few neurosecretory granules. In the opossum, pituicytes have a densely fibrillar cytoplasm. Herring bodies are prominent in the hilar region. They are large bodies packed with neurosecretory granules that have been described as end bulb formations of axons. From the hilar region, axons fan out into a palisade zone where the nerve terminals packed with neurosecretory granules, mitochondria, and microvesicles abut upon basement membranes. The neurosecretory granules are similar to those present in the neurohypophysis of other mammals, except for an occasional huge granule of distinctive type. Material morphologically and histochemically resembling glycogen occurs as scattered particles and as aggregates within nerve fibers. The septal zone, containing collagen, fibroblasts, and numerous small capillaries, is separated from the adjacent glandular tissue by a basement membrane.     

SHELL STRENGTH OF COLOUR MORPHS OF THE MANGROVE SNAIL LITTORARIA PALLESCENS

The load required to break shells of the snail Littor-aria pallescens(Philippi) (Gastropoda: Littorinidae) has been established.Mass increases more than proportionally with size. Size forsize, relatively heavy shells are thicker than relatively lightones, and the thicker shells are stronger. Three samples fromdifferent localities differ significantly in strength. Littorariapallescens is polymorphic for shell colour. It is shown thatin two of the three samples, both from Papua New Guinea, individualsof the dark morph are significantly heavier and stronger thanthose of the yellow morph, while there is no difference betweenmorphs in the third sample, from Thailand. In the sample withthe most robust shells the dark individuals are stronger, massfor mass, than yellows. Thus, colour morph is sometimes, butnot always, associated with differences in shell characteristicswhich are likely to affect fitness. Where there is a difference,the dark morph is estimated to be on average about 22% strongerthan the yellow morph. The difference between morphs is smallcompared with the large variation in shell characters associatedwith size. (Received 20 May 1992; accepted 22 June 1992)     

THE PALLIAL EYES OF CTENOIDES FLORIDANUS (BIVALVIA: LIMOIDEA)

The structure of the pallial eye in the Limidae has neverbeen elucidated properly, largely because they are difficultto see among the mass of surrounding mantle tentacles and becausethey are few, small, and lose their pigmentation when preserved.Possibly two eye types are present, simple cup-shaped receptorsin species of Lima, like those seen in the Arcoida, and morecomplex invaginated ones in Ctenoides. The pallial eyes (;18on both lobes) of Ctenoides floridanus are formed by invaginationof the middle mantle fold at the periostracal groove, so thatall its contained structures are derived from the outer andlight is perceived through the inner epithelia of this fold.The eye comprises a simple multicellular lens and a photoreceptiveepithelium beneath it of lightly pigmented cells and alternatingvacuolated, support cells. In some species of the Arcoidea, Limopsoidea and Pterioidea, pallialeyes occur on the outer mantle fold and thus beneath the periostracum(and shell). The pallial eyes of Ctenoides floridanus and otherpterioideans, e.g. species of the Pectinidae, occur on the middlefold and may thus have improved vision. In the Cardiodea, Tridacniidaeand Laternulidae (Anomalodesmata) pallial eyes occur on theinner folds. There is thus a loose phylogenetic trend, in which Ctenoidesis a critical link, of increasing eye sophistication correlatedwith the historical age of the clades possessing them. (Received 16 November 1999; accepted 20 January 2000)     

Heterophylly in Ranunculus flabellaris: The Effect of Abscisic Acid on Leaf Anatomy

Ranunculus flabellaris Raf., the yellow water crowfoot, exhibitsstriking heterophylly between submerged and terrestrial leaves.Leaves produced under water are highly divided with numerousnarrow lobes and deep sinuses, whereas terrestrial leaves havefew broad lobes and shallow sinuses. When plants are submergedin a 25 µM solution of ABA, the typical transition fromterrestrial to submerged leaves is completely suppressed and,instead, terrestrial-like leaves are produced. Image analysistechniques show that, in addition to this modification of leafmorphology, leaves produced under ABA treatment possess surfaceand internal features characteristic of terrestrial leaf anatomy.This study provides evidence that the environmental factorsthat influence the morphological and anatomical expression ofheterophylly may act through endogenous ABA. Ranunculus flabellaris, yellow water crowfoot, ABA, heterophylly, leaf anatomy     

Pigment Bodies in Fruits of Crimson and High Pigment Lines of Tomatoes

Pigment bodies in fruits of crimson (og^c), high pigment (hp),and crimson-high pigment (og^c hp) lines of tomatoes were observedby electron and light microscopy and compared with those ofnormal red lines and a yellow cultivar. During chloroplast-chromoplasttransformation, two main structurally distinct bodies are produced,their total and relative amounts apparently accounting for theentire range of colours (from very deep red to yellow) characterizingthe mature fruits of these different colour lines. The longnarrow crystalloids, believed to be lycopene, form in associationwith an extended thylakoid system; in senescing (over-ripe)fruit many of these are reduced to shorter irregular forms.The rounded globules are believed to be beta-carotene dissolvedin lipid material derived from membrane lysis. Analytical resultscorroborate microscopic observations that the effect of theog^c gene, as compared with the r⁺ gene for normal red colour,is to increase the lycopene content and lower the beta-carotenecontent. The effect of the hp gene is to increase the levelsof both pigments. The results support the view that the genescontrol the development of fruit pigments which affect chromoplastultrastructure. Lycopersicon esculentum Mill, tomato, fruit, pigment bodies, beta-carotene, lycopene     

白蚁跟踪信息素及其类似物的活性比较试验初报

自从1967年Smythe等发现某些真菌寄生过的木材中含有一种活性物质,与白蚁腹腺分泌的跟踪信息素有相似的效用以后,引起了人们探讨白蚁踪迹物质的浓厚兴趣。白蚁是一种社会性昆虫。群体间的觅食、防卫、筑巢、交哺等行为都是通过信息物质的调节来进行的。所以开展白蚁跟踪信息素及其类似物的研究,有可能为我们找出一条新的防治途径。     

NORTH ATLANTIC NUDIBRANCHS OF THE CHROMODORTS CLENCHI COLOUR GROUP (OPISTHOBRANCHIA: CHROMODORIDIDAE)

The correct identity of three chromodorid nudibranch species,Chromodoris clenchi, C. neona and C. binza is established onthe basis of material from the Caribbean Sea. These three speciesare compared with C. britoi, from the northeastern Atlanticand the Mediterranean Sea. All four species have a colour patternof cream with red (or yellow) lines and blue spots. (Received 30 March 1993; accepted 20 November 1993)     

西藏真蚋一新种(双翅目：蚋科)

西藏真蚋一新种（双翅目：蚋科）邓成玉,张有植,薛群力,陈汉彬（成都军区卫生防疫队成都６１００６１）（贵阳医学院贵阳５５０００４）１９８９年５月,作者在进行西藏亚东烟类调查时,发现烟属真纳亚属一新种,现记述如卜。新纤细真纳Ｓｉｔｈｄｓ（ＥＭｂｏｄｓｎ们...     

MICRODISTRIBUTION IN THE FIELD AND HABITAT CHOICE IN AQUARIA BY COLOUR MORPHS OF LITTORINA MARIAE SACCHI & RASTELLI

The microdistributions of yellow and brown morphs of adult andjuvenile Littorina mariae were investigated in the field onFucus plants. On F. vesiculosus in autumn, yellow adults werefound more frequently than expected on laminae and brown adultsmore frequently than expected on stipes. In spring there wasno difference in distribution between adult morphs. There wasno difference in microdistribution betweenjuvenile morphs oneither F. vesiculosus or F. serratus in autumn. Yellow and brown adults were allowed to choose between an artificialbrown and an artificial yellow background, and between stipeand lamina of F. serratus in aquarium experiments. Both morphspreferred the yellow rather than the brown background. In mostcases, the morphs climbed upwards on F. serratus, regardlessof algal orientation (lamina upwards or stipe upwards) or lightregime (lights on or off). A significant difference in microdistributionbetween morphs was found with the lamina placed upwards andthe lights on. Brown snails then preferred stipe, while yellowsnails did not show a preference for either stipe or lamina. (Received 16 June 1994; accepted 31 October 1994)     

Plastid Ontogeny in the Corolla Cells of Digitalis purpurea L. cv. Foxy

Initially the corolla plastids of Digitalis purpurea containsmall grana with negatively stained thylakoids. Degenerationof the grana, loss of chlorophyll and the transient accumulationof starch accompany corolla expansion Starch disappears by thetime the anthers dehisce and granular and amorphous phytoferrtindeposits become prominent in the stroma Concomitant with theseparation of the stigmatic lobes the thylakoid system is reducedto a central membranous network enveloping the phytofemtm aggregatesJust prior to corolla abscission the stroma becomes packed withplastoglobuh Although this developmental sequence closely resemblesthat for chromoplasts in yellow and red flowers, fruits andautumn leaves there is no synthesis of carotenoid pigments inthe corollas of Digitalis purpurea At maturity the plastidsare therefore best described as elaioplasts. Digitalis purpurea L., foxglove, corolla, plastids, elaioplasts, phytofemtin, ultrastructure, X-ray microanalysis     

THE ROLE OF LYMNAEA AURICULARIA (LINNAEUS) AND LYMNAEA PEREGRA (MULLER) (GASTROPODA: PULMONATA) IN THE TRANSMISSION OF LARVAL DIGENEANS IN THE LOWER THAMES VALLEY

Eleven species of larval digeneans are reported for the firsttime in the UK from the freshwater snail Lymnaea (Radix) auricularia.The latter replaced its congener L. peregra in a gravel pitnear Wraysbury, Berkshire in the Lower Thames Valley and hostedan assemblage of larval digeneans similar to that previouslytransmitted by L peregra. The larval digeneans of L. peregrain small bodies of water in the area were also similar to thosefound in L. auriculania in the gravel pit. This replacementin the role of the host is explained on the basis of morphological,physiological and ecological similarities of the two lymnaeidspecies. (Received 19 February 1992; accepted 27 April 1992)