The ‘philosophical grasp of the appearances’ and experimental microscopy: Johannes Müller’s microscopical research, 1824–1832

Romantic Naturphilosophie has been at the centre of almost every account of early nineteenth-century sciences, be it as an obstacle or as an aid for scientific advancement. The following paper suggests a change of perspective. I seek to read Naturphilosophie as one manifestation among others of a more general concern with the question of how experience enables the subject to acquire knowledge about objects. To illustrate such an approach, I focus on Johannes Müller’s early work. Here one finds two contrasting images of microscopical observation, its set-up, and the observer: the embryological study of 1830 demands a ‘philosophical grasp’ of the appearances. In contrast, the investigations of blood of 1832 are presented as a series of controlled experiments. I argue that an interpretation of this contrast in terms of an appropriation and casting aside of Naturphilosophie is not altogether convincing. Instead, both images of microscopy are manifestations of a more general problem, namely, the problem of exactly how subject and object came together in experience. I show how this concern not only shaped the methodological sensibilities particular to Müller’s embryology and the investigation of bodily liquids but also provided the epistemological principles and the target for his sense-physiological experiments. It bound Müller’s work together with Naturphilosophie and linked Naturphilosophie with other contemporaneous projects in philosophy. All of these enterprises sought to contribute to ongoing debates about how experience allowed the subject to acquire knowledge about the world.     

Age related evolution of sexual dimorphism in the Red-necked NightjarCaprimulgus ruficollis

Some morphological and sexual characters were measured in juvenile, first-year and adult Red-necked Nightjars in SW Spain. We found significant age-related growth in wing, tail and body mass, first-year birds being heavier than adults. Adults showed sex differences in tail and wing lengths, and the size of tail and wing spots differed between males and females of all age classes. There was not any difference in the number of wing spots, and juvenile males had a lower number of tail spots than older males. An age-related increase in sexual dimorphism was found to exist by size increase of wing spots in males. Since wing and tail spots are exhibited in courtship displays, the elongation of these secondary sexual characters could be related to mate choice mechanisms.

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Zusammenfassung Einige morphologische Merkmale juveniler, einjähriger und adulter Rothals-Ziegenmelker (Caprimulgus ruficollis) in SW Spanien wurden gemessen. Es ergaben sich signifikante altersbedingte Unterschiede in Flügel- und Schwanzlänge sowie in der Körpermasse; einjährige Vögel waren schwerer als erwachsene. Adulte Vögel wiesen geschlechtsabhängige Unterschiede in der Flügel- und Schwanzlänge auf; die Größe der Schwanz- und Flügelflecken unterschieden sich zwischen Männchen und Weibchen aller Altersklassen. Es gab keine Unterschiede in der Anzahl der Flügelflecken; juvenile Männchen hatten aber weniger Schwanzflecken als ältere. Eine durch das Wachstum der Flügelflecken der Männchen bedingte Zunahme des Sexualdimorphismus wurde gefunden. Da die Flügel und Schwanzflecken bei der Balz eine Rolle spielen, könnte die Vergrößerung dieser sekundären Geschlechtsmerkmale mit Paarwahlmechanismen zusammenhängen.

     

The Muller-Lyer illusion explained and its theoretical importance reconsidered

The Müller-Lyer illusion is the natural consequence of the construction of the vertebrate eye, retina and visual processing system. Due to imperfections in the vertebrate eye and retina and due to the subsequent processing in the system by ever increasing receptive fields, the visual information becomes less and less precise with respect to exact location and size. The consequence of this is that eventually the brain has to calculate a weighted mean value of the information, which is spread out over a population of neurons. In the case of the Müller-Lyer illusion this inevitably leads to extension of one and reduction of the other line. The arguments presented explain several published experimental results concerning the Müller-Lyer illusion and shed new light upon the philosophical neutrality of observation sentences.     

DFT and MP2 studies on the C2C2α bond cleavage in thiamin catalysis

Thiamin diphosphate (ThDP), the biologically active derivative of vitamin B₁, is an important cofactor of several enzymes that catalyze the oxidative and non-oxidative conversion of α-keto acids. The final step of non-oxidative decarboxylation of pyruvate by pyruvate decarboxylase – the liberation of acetaldehyde – requires deprotonation of the α-hydroxyl group and cleavage of the C2–C2α bond of the transitory 2-(1-hydroxyethyl)-ThDP intermediate. It has been proposed that the cofactor 4′-amino/imino function is essentially involved in the deprotonation of the α-hydroxyl group. Proton transfer and C2–C2α cleavage may occur in a stepwise manner, or, alternatively in a concerted mechanism. Here, density functional theory (DFT) calculations as well as second order Møller–Plesset perturbation theory (MP2) studies were performed on a simple model for the enzyme using the program package Gaussian 03. Calculations favor a stepwise mechanism with initial formation of the C2α alkoxide, followed by C2–C2α bond cleavage.     

Die spektrale Transmission des dioptrischen Apparates von Aeschna cyanea Müll.

Zusammenfassung Die spektrale Transmission wurde mit dem UMSP (UniversalMicro-Spektralphotometer) im Bereich von 550–300 nm am fixierten (Carnoy) und frischen dioptrischen Apparat einzelner Ommatidien von Aeschna cyanea Müll. (Odonata) gemessen.Die Transmission der Kristallkegel und der frischen Cornea ist zwischen 550–370 nm nahezu konstant; bei kürzeren Wellenlängen des UV-Bereiches sinkt die Transmission etwas. Erst bei Wellenlängen, die kürzer als 330 nm sind, wird der Transmissionsabfall signifikant.

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The spectral transmission of the dioptric apparatus of aeschna

Summary Spectral transmission was measured by means of a Zeiss Universalmicro-spectralphotometer between 550 and 300 nm on fixed (Carnoy) and also on fresh cornea and crystalline cones of single ommatidia of Aeschna cyanea Müll. (Odonata).Both crystalline cones and fresh corneas (in contrast to fixed corneas) have nearly constant transmission from 550 to 370 nm; in uv-range with shorter wavelengths the transmission decreases slightly. Only at wavelengths shorter than 330 nm is the absorption significant.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

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Mit Unterstützung der Alexander von Humboldt-Stiftung.     

Die abwandlung des eilegeapparates der bombyliidae (Diptera) Eine funktionsmorphologische studie

Skeleton, muscles, and functioning of the egg-laying systems of 38 species out of 16 subfamilies are studied. A development sequence toward a soil chamber to coat the eggs (b, c) can be characterized by the sternite 8: a) its inward position (Geroninae), b) its erection (9 subfamilies), c) its shell-shaped cavity (Exoprosopinae). Systropodinae and Heterotropinae cannot be fitted into this system.

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Abkürzungen in den Abbildungen VI–X 6.–10. Tergit - 6–8 6.–8. Sternit - A Analöffnung - Ac Acanthophorit 8. Sternits - Ac IX vom 9. Tergit abgetrenntes Acanthophorit - adr 1 schlauchförmige Geschlechtsanhangsdrüse - adr 2 wurstförmige Geschlechts-anhangsdrüse - Af After - AG Apikaler Gangabschnitt des R. sem. - Ak Analkegel - B IX Ausbuchtung am 9. Tergit - BG Basaler Gangabschnitt des R. sem. - Bo Borsten - Br präformierte Bruchstelle am Eideckel - Bu Bursatasche - Ch Chorion - Cö Coecum - D Darm - De Eideckel - Do Dornen - Do VIII Dornen am 8. Tergit - dR-S8 dorsaler Rand von Sternit 8 - Ed Enddarm - EmMG Einmündung der MalpighiGefäße - Er Eierrinne - Ggl 6, 7 Ganglion des 6. bzw. 7. Ab dominalsegments - Gö Geschlechtsöffnung - gOd gemeinsamer Eiergang - HaEr Haarflur entlang der Eierrinne - Ha-S8 Haare am 8. Sternit - Ha-Tv8 Haare an der Unterkante des 8. Tergits - hM häutiges Mittelfeld auf dem 8. Sternit - HPi Haarpinsel am 8. Tergit - Krs Kropfsack - Krst Kropfstiel - Ku Kufen am 8. Tergit - Lö häutige Löffelbildung - IZ lappenartige Zipfel des - M 1,2 Muskel Nr. 1, 2, etc. - MA Muskelapparat im Ductus receptaculi - Md Mitteldarm - Müadr 2 Mündung der Anhangsdrüsen-2 - MüRs Mündung der R. sem. - Od Ovidukt - Ov Ovar - PGP Postgenitalplatte - Pl Pleura - Po verdaute Pollenkörner im Enddarm - R VIII Rostrum am 8. Tergit - Rbl Rectalblase - rEi reifes Ei - Rp Rectalpapille - R. sem. Receptaculum seminis - S Sternit - Sbl Samenkapsel des R. sem. - SGP Subgenitalplatte - Sk Sandkammerbucht - Skl IX Sklerit im Dach der Sandkammerbucht - Spb Spatelborsten - Spdr Speicheldrüsen - Stg Stigma - T Tergit - Tv ventromedial verälangertes Tergit 8 - U IX, U X Zungenfortsatze des 9. bzw. 10. Tergits im Dach der Sandkammerbucht - U Ac Zungenfortsätze des Acan thophorits im Dach der Sandkammerbucht - Vag Vagina - Vag. Ap. Vaginalapodem - Vag-Es Vagina-Einsenkung in die Sternit 8-Schale - Vh Ventralhaut des Analkegels     

Monomolecular surface film and tubular myelin figures of the pulmonary surfactant in hamster lung

Summary Perfusion fixation via pulmonary trunk was applied to the alveolar lining layer in situ at different lung volumes using a fixative containing tannic acid-ferrocyanide osmium. The monomolecular surface film and hypophasic tubular myelin figures were enhanced. In the range of transpulmonary pressure (1–10 cmH₂O), the surface film appeared in the form of a single, electron-dense leaflet, 2.7±0.6 nm (M±SD) in thickness while trilaminar membrane structure was retained in all parts of the tubular myelin figures of the hypophase. The surface film was attached underneath at right angles with trilaminar membranes which formed the outermost parts of the tubular myelin. Such structural continuity was taken to support a view that the phospholipid unit membrane of the tubular myelin figure would be transformed at the hydrophobic phase into a pair of monomolecular leaflets, eventually forming the surface film.     

The Müller-Lyer Illusion in Ant Foraging

The Müller-Lyer illusion is a classical geometric illusion in which the apparent (perceived) length of a line depends on whether the line terminates in an arrow tail or arrowhead. This effect may be caused by economic compensation for the gap between the physical stimulus and visual fields. Here, we show that the Müller-Lyer illusion can also be produced by the foraging patterns of garden ants (Lasius niger) and that the pattern obtained can be explained by a simple, asynchronously updated foraging ant model. Our results suggest that the geometric illusion may be a byproduct of the foraging process, in which local interactions underlying efficient exploitation can also give rise to global exploration, and that visual information processing in human could implement similar modulation between local efficient processing and widespread computation.     

The Impact of Spatial Incongruence on an Auditory-Visual Illusion

Background

The sound-induced flash illusion is an auditory-visual illusion – when a single flash is presented along with two or more beeps, observers report seeing two or more flashes. Previous research has shown that the illusion gradually disappears as the temporal delay between auditory and visual stimuli increases, suggesting that the illusion is consistent with existing temporal rules of neural activation in the superior colliculus to multisensory stimuli. However little is known about the effect of spatial incongruence, and whether the illusion follows the corresponding spatial rule. If the illusion occurs less strongly when auditory and visual stimuli are separated, then integrative processes supporting the illusion must be strongly dependant on spatial congruence. In this case, the illusion would be consistent with both the spatial and temporal rules describing response properties of multisensory neurons in the superior colliculus.

Methodology/Principal Findings

The main aim of this study was to investigate the importance of spatial congruence in the flash-beep illusion. Selected combinations of one to four short flashes and zero to four short 3.5 KHz tones were presented. Observers were asked to count the number of flashes they saw. After replication of the basic illusion using centrally-presented stimuli, the auditory and visual components of the illusion stimuli were presented either both 10 degrees to the left or right of fixation (spatially congruent) or on opposite (spatially incongruent) sides, for a total separation of 20 degrees.

Conclusions/Significance

The sound-induced flash fission illusion was successfully replicated. However, when the sources of the auditory and visual stimuli were spatially separated, perception of the illusion was unaffected, suggesting that the “spatial rule” does not extend to describing behavioural responses in this illusion. We also find no evidence for an associated “fusion” illusion reportedly occurring when multiple flashes are accompanied by a single beep.     

Phytoplankton of Lake Peipsi-Pihkva: species composition, biomass and seasonal dynamics

With 33 years of phytoplankton quantitative studies carried out, a series of qualitative data with a length of over 80 years is at our disposal. About 500 algal species have been found in plankton by different researchers. In different seasons and years 35 main species (dominants and subdominants) form 68–96 % of biomass in L. Pihkva (southern, more eutrophic part) and 60–97 % in L. Peipsi (northern, less eutrophic part). L. Lämmijärv, connecting the two parts is similar to L. Pihkva in respect to phytoplankton and the trophic state. Diatoms and blue-green algae prevail in biomass, diatoms and green algae, in the species number. The oligo-mesotrophic Aulacoseira islandica (O. Müller) Sim. is characteristic of the cool period; A. granulata (Ehr.) Sim. and Stephanodiscus binderanus (Kütz.) Krieger prevail in summer and autumn, the latter being most abundant in the southern part. Gloeotrichia echinulata (J.S. Smith) P Richter and Aphanizomenon flos-aquae (L.) Ralfs dominate in summer causing water-bloom. Phytoplankton has mostly three maxima in seasonal dynamics in L. Peipsi and two in L. Pihkva. Its average biomass in spring in different years has fluctuated in the range 5.6–16 and 6–12.7 g m^–3, in summer 3.1–14.8 and 5.6–125 (10–20 in most cases); and in autumn 7–16.3 and 5.2–26 in the northern and southern parts, respectively.The dominant complex has not changed considerably since 1909; however, the distribution of dominant species in lake parts has become more even in the last decades. Periods of high biomass occurred in the first half of the 1960s and 1970s and in 1988–1994, of low biomass in 1981–1987. The first coincided, in general, with periods of low water level and high water temperature.     

Cooperative breeding by Alpine AccentorsPrunella collaris: Polygynandry, territoriality and multiple paternity

The composition of breeding groups, territoriality, parentage and parental care were examined in a population of Alpine AccentorsPrunella collaris in the Swiss Alps. Five (1993) and six (1994) breeding groups were located on a south facing hillside between 2500 and 2860 m above sea level. 3–5 males cooperated in the defence of their group territory, wherein 2–3 females each held an exclusive territory (separate nesting polygynandry). Males competed for access to fertile females within their group territory. The females copulated promiscuously with all or several males within their breeding group. The - and -males had more access than other subordinate males. They combined frequent copulations and mate guarding as types of paternity guards. The female performed most of the parental care. Usually, 1–4 males helped feeding the young. Results of DNA-profiling showed that members of one group were seldom closely related. In three out of five sampled broods, multiple paternity occurred with up to three males siring offspring within one clutch.

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Zusammenfassung Die Zusammensetzung der Brutgruppen, Territorialität, Vaterschaft und elterliche Fürsorge von Alpenbraunellen wurden untersucht. Die Population bestand aus fünf (1993) und sechs (1994) Brutgruppen und besiedelte einen 60 ha großen Südhang in den Walliser Alpen zwischen 2500 und 2860 m ü. M. Das Habitat besteht aus alpinen Rasen, Blockschutt und Felsgruppen. Bereits im Februar und März halten sich die Männchen in ihren späteren Brutgebieten auf und singen. Ende April sind die Brutgruppen gebildet. Im untersuchten Gebiet konnte nur Polygynandrie gefunden werden, d. h. 3–5 Männchen kooperieren bei der Verteidigung ihres Gruppenterritoriums, worin 2–3 Weibchen jeweils ihr exklusives Territorium halten. Die Männchen konkurrieren in langen und intensiven Verfolgungsflügen um den Zugang zu fertilen Weibchen innerhalb ihres Gruppenterritoriums. Die Weibchen können sich während ihrer fertilen Phase mehrmals pro Stunde mit verschiedenen Männchen paaren. Hierbei erhalten Alpha- und Beta-Männchen größeren Zugang als rangniedere. Männchen kombinieren eine hohe Kopulationsrate und Weibchen-Bewachung, um ihren Anteil an der Vaterschaft zu erhöhen. Resultate mittels DNA-Profiling ergaben in rund der Hälfte der Bruten multiple Vaterschaft mit bis zu drei beteiligten Vätern. Das Weibchen trägt den Hauptteil der Brutpflege. Es baut das Nest allein und übernimmt die Bebrütung der ein bis vier Eier. Bei der Fütterung der Nestlinge hingegen helfen bis zu vier Männchen mit, deren Einsatz aber geringer ist als derjenige des Weibchens.

     

Reinvestigation of molecular structure and barrier to internal rotation of pyridinium N-phenolate betaine dye

In the present paper, the results of a systematic theoretical study of the molecular structure of 4-(1-pyridinium-1-yl)phenolate betaine are reported. The ground-state molecular structure and the barrier to internal rotation of the betaine dye molecule were calculated ab inito (with Hartree–Fock theory and the second-order of Möller–Plesset method) and with density functional theory (DFT). In order to estimate the complete basis set limit, the calculations of barriers to internal rotations were performed using correlation–consistent basis sets with a maximal cardinal number of four. It was determined that electron correlation is crucial in order to obtain reliable geometries and rotational barriers of the molecule investigated. For the sake of comparison, the results of calculations using the AM1 Hamiltonian are also presented.Figure Investigated betaine dye.     

Fledermäuse im Windkanal

Zusammenfassung In einem Windkanal wurde für eine Myotis lucifugus die Abhängigkeit der Fluggeschwindigkeit (v_F) und der Geschwindigkeit über Grund (v_G) von der Windgeschwindigkeit (v_W) bestimmt. Die Fledermaus flog bei Windstille mit einer mittleren v_F von etwa 4,5 m/sec. Bei zunehmenden Gegenwinden erhöhte sie v_F und verringerte v_G, um bei v_W=7,7 m/sec für kurze Zeit stationären Flug (v_G=0) zu erreichen. Die Flügelschlagfrequenz lag bei Gegenwinden von 0–7,7 m/sec zwischen 10–11/sec. Bei zunehmenden Rückenwinden wurde der Flug immer mehr dem Rüttelflug ähnlich und die Flügelschlagfrequenz stieg bis 16/sec an. Die v_G blieb nahezu konstant in einem Bereich zwischen 4,5–5 m/sec. Bei Myotis lucifugus, Chilonycteris rubiginosa, Carollia perspillicata und Rhinolophus ferrum-equinum wurde die Flügelstellung während der Lautaussendung ermittelt. Alle Arten erzeugten entweder einen Einzellaut oder eine Gruppe von Lauten pro Flügelschlag.

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Bats in the wind tunnel

Summary In an experimental wind tunnel air speed (v_F) and ground speed (v_G) of a Myotis lucifugus were measured as a function of wind speed (v_W). The bat had a v_F of about 4,5 m/sec in still air. With head winds it increased v_F and lowered v_G to reach stationary flight (v_G=0) at a v_W of 7,7 m/sec. The rate of wing motion remained at about 10–11/sec at head winds from 0–7,7 m/sec. With tail winds the bat changed to a semi-hovering flight with wing beat frequencies rising to about 16/sec and v_F dropping to almost zero at 4–5 m/sec tailwinds. The v_G remained nearly constant between about 4,5–5 m/sec. (Figs. 2 and 3). The wing positions during which orientation sounds were emitted were determined for Myotis lucifugus (Fig. 4), Chilonycteris rubiginosa, Carollia perspillicata and Rhinolophus ferrum-equinum (Fig. 5). All bats emitted either one single sound or a group of sounds per wing beat.

     

The action of glutamate and the problem op the “extracellular space” in the retina

Summary Turtle's retinae were incubated in isotonic Ringer and then studied with the electron microscope in order to determine if in these conditions an extracellular space appeared. In the incubated retinae, as in the normal ones no extracellular space was observed. The distance between adjacent membranes is of 120–250 Å and is filled with a cementing material.The Müller cell of the turtle's retina is described. The existence, at the choroidal end of this cell, of villous projections filled with vesicles and the accumulation of mitochondria under these projections would suggest that a process of micropinocytosis takes place in this site, and that it may be metabolically more active. After incubation, Müller cells showed no appreciable changes, in contrast with what happens to astrocytes in incubated slices of CNS (Gerschenfeld et al. 1959).The addition of sodium-l-glutamate to the incubation medium determined a marked swelling of the nervous endings in the inner synaptic layer and a similar though less pronounced change in the ganglion cells. This would indicate that the surcharge of water, sodium and chloride produced by glutamate (Ames 1956) is localized in this layer.The selective action of glutamate on the inner synaptic layer, in contrast with the excellent preservation of the outer synaptic layer, is probably linked to differences in biochemistry and physiology of synapses in these two strata.Work supported by a research grant from the Air Force Office of Scientific Research (5–60), U.S.A.     

Immigration of the brown planthopper, Nilaparvata lugens, exhibiting various responses to density in relation to wing morphism

Considerable inherent variations in the relation between macropterous and brachypterous wing forms, and nymphal density were found in field populations of the brown planthopper, Nilaparvata lugens Stål (Homoptera: Delphacidae), collected from various locations in Japan. When compared under uniform laboratory rearing conditions, most of the female populations exhibited higher ratios of macropters with increasing nymphal density, but some showed extremely high proportion of brachypters and the others were highly macropterous, over broad ranges of density. These results indicate the possibility that the planthoppers in Japan, which are known not to persist in winter, are derived from different migration sources.About ten generations of successive selection for brachyptery from a population showing usual density-dependent wing morphism generated populations similar to highly brachypterous ones mentioned above. Genetic analysis of the inheritance of wing morphism revealed that brachyptery in the females was controlled by a single pair of dominant alleles. However, in the males wing forms did not segregate so clearly in the crossing experiments. This suggests that wing morphism in N. lugens in under sex-limited inheritance.

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Einwanderung von Nilaparvata lugens mit unterscheidlicher Reaktion auf Populationsdischte bei der Flügelausbildung

Zusammenfassung In Feldpopulationen von Nilaparvata lugens Stål., welche in verschiedenen Regionen Japans gesammelt wurden, bestand in der Beziehung zwischen makropteren bzw. brachypteren Flügelformen und der Larvendichte eine beträchtliche Variation. Unter einheitlichen Zuchtbedingungen im Laboratorium stieg der Makropterenanteil bei den meisten Weibchenpopulationen mit steigender Temperatur; bei einigen Populationen hingegen war entweder der Brachypterenanteil oder der Makropterenanteil extrem hoch und zwar über weite Dichtebereiche. Dies deutet auf die Möglichkeit hin, dass die Zikade in Japan, wo sie bekanntlich nicht überwintert, jeweils aus verschiedenen Quellen einwandert.Wenn eine Population mit der üblichen dichteabhängigen Flügelausbildung 10 Generationen lang auf Brachypterie selektioniert wurde, entstanden Populationen, die den erwähnten hochbrachypteren Populationen aus dem Feld glichen. Die genetische Analyse der Vererbung der Brachypterie ergab, dass bei Weibchen ein einzelnes dominantes Allel verantwortlich ist. Bei Männchen dagegen trennten sich bei Kreuzungsexperimenten die Flügelformen nicht so klar. Dies deuted auf Unterschiede zwischen den Geschlechtern bei der Vererbung der Flügelformen.

     

Die Winterfestigkeit keimgestimmter Gersten

Zusammenfassung 5 Wintergerstensorten, I Sommergerstensorte und 4 Wintergerstenzuchtstämme des Kaiser Wilhelm-Instituts für Züchtungsforschung in Müncheberg (Mark) wurden auf ihre Winterfestigkeit nach 20–, 30–, und 40 tägiger Keimstimmung im Frelland geprüft. Bei allen Sorten und Stämmen setzt die Keimstimmung die Winterfestigkeit stark herab, am geringsten ist der Abfall der Winterfestigkeit bei den winterfestesten Sorten. Die Jarowisation wirkt auf den Plasmazustand ein und verhindert das Plasma an der Erlangung eines kälteunempfindlichen Zustandes. Mit Hilfe der Keimstimmung kann die Auslese von winterfesten Formen beschleunigt und gesichert werden.     

Untersuchungen über die Entwicklungsgeschichte der Myxomyceten. Sexualität und Apogamie bei Didymiaceen

Ohne ZusammenfassungMit 1 Textabbildung (5 Einzelbildern) und Tafel I–III.Dissertation der Philosophischen Fakultät, II. Sektion der Ludwig Maximilian-Universität zu München.     

Dissociation of color and figure-ground effects in the watercolor illusion

Two phenomena can be observed in the watercolor illusion: illusory color spreading and figure-ground organization. We performed experiments to determine whether the figure-ground effect is a consequence of the color illusion or due to an independent mechanism. Subjects were tested with displays consisting of six adjacent compartments--three that generated the illusion alternating with three that served for comparison. In a first set of experiments, the illusory color was measured by finding the matching physical color in the alternate compartments. Figureness (probability of 'figure' responses, 2AFC) of the watercolor compartments was then determined with and without the matching color in the alternate compartments. The color match reduced figureness, but did not abolish it. There was a range of colors in which the watercolor compartments dominated as figures over the alternate compartments although the latter appeared more saturated in color. In another experiment, the effect of tinting alternate compartments was measured in displays without watercolor illusion. Figureness increased with color contrast, but its value at the equivalent contrast fell short of the figureness value obtained for the watercolor pattern. Thus, in both experiments, figureness produced by the watercolor pattern was stronger than expected from the color effect, suggesting independent mechanisms. Considering the neurophysiology, we propose that the color illusion follows from the principles of representation of surface color in the visual cortex, while the figure-ground effect results from two mechanisms of border ownership assignment, one that is sensitive to asymmetric shape of edge profile, the other to consistency of color borders.     

Age-related flight and reproductive performance of the light brown apple moth, Epiphyas postvittana

The relationship between flight activity, reproduction and age of Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) was studied using tethered flight assays. Flights began on the day of emergence, peaking on days four and five in females and on day five in males, and lasted for nine to ten days. The development of flight capacity was well synchronised with the build-up and decline of reproductive behaviours (calling, mating and oviposition). Flights of E. postvittana are thus inter-reproductive, and there is no obvious pre-oviposition period. Males were more active than females as 45–50% of male moths in comparison to 15–18% of female moths were capable of prolonged flights during the peak activity period. The results suggest that flights of E. postvittana are appetitive flights to a large extent, but it is suggested that some individuals may migrate, as there is no diapause in this species. The sexual dimorphism of flight capacity is discussed in relation to those of other tortricids and Lepidoptera in general.

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Zusammenfassung Die Beziehungen zwischen Flugaktivität, Fortpflanzung und Alter von Epiphyas postvittana (Walker) (Tortricidae) wurden untersucht mit Hilfe von angebudenen Flugapparaten. Flüge begannen am Tage des Schlüpfens, mit einen Maximum am vierten und fünften Tag bei Weibchen und am fünten Tag bei Männchen, und dauerten neun bis zehn Tage. Die Entwicklung des Flugvermögens war gut mit der Zu- und Abnahme des Fortpflanzungsverhaltens (Rufen, Kopulieren und Eiablage) korreliert. Flüge von E. postivittana finden also während der Fortpflanzungsperiode statt, und es gibt keine deutliche Periode vor der Eiablage. Männchen waren aktiver als Weibchen: 45–50% der Männchen verglichen mit 15–18% der Weibchen waren zu langen Flügen während der maximalen Aktivitätsperiode fähig. Das Ergebnis deutet an, das Flüge von E. postvittana im grossen Masse Appetenzflüge sind, doch es wird auf die Möglichkeit hingewiesen, dass einige Individuen wandern können, da die Art keine Diapause hat. Der Geschlechtsdimorphismus in der Flugaktivität wird diskutiert und verglichen mit dem anderer Tortriciden und der Lepidoptera allgemein.

     

Rearing, reproductive behaviour and gamma sterilization of fruit fly, Dacus zonatus (Diptera: Tephritidae)

Investigations were made on rearing, reproductive behaviour and gamma sterilization of one-day old male adults of Dacus zonatus. The larvae were successfully reared on an artificial diet based on wheat shorts. Adult emergence ranged from 89–99% with a sex ratio of about 1:1. Mating occurred at dusk and its duration ranged from 8–13 hours. Males mated a second time with the same female but preferred mating if the already mated female was replaced with a sexually mature virgin female. The optimum dosage for inducing sterility amongst one-day old male adults was 12 kR.

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Zusammenfassung Zucht und Fortpflanzungsverhalten von Dacus zonatus (Saunders) wurde untersucht. Die Larven wurden vier Generationen lang an einer Diät aus Weizenkleie, Bierhefe, granuliertem Zucker, Agar, Nipagin, Salzsäure und Wasser gehalten. Die Arbeit gibt Daten über Verpuppungsprozentsatz (69,3%), Puppengewicht, Dauer der Ei + Larvenperiode, Schlüpfen der Adulten, Präovipositionszeit, Fruchtbarkeit, Fertilität und Lebensdauer der Adulten. Die Schlüpfrate der Adulten betrug 89–99%, das Geschlechtsverhältnis lag etwa bei 1:1. Die Kopulation findet während der Abenddämmerung statt, sie dauert 8–13 Stunden. Maximum der Kopulationen zwischen dem 10. und 15. Tag nach dem Schlüpfen. Männchen paarten sich ein zweites Mal mit dem gleichen Weibchen, bevorzugten jedoch geschlechtsreife jung-fräuliche Weibchen. Die Eiablage begann am 2.–7. Tag nach der Paarung, die Eizahl betrug bei gepaarten Weibchen 91–564.Die optimale Dosis zur Erzeugung von 99,3% Sterilität bei Bestrahlung von einem Tag alten Männchen war 12 kR. Die Lebensdauer der Bestrahlten war vermindert.