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  • Animals  (2,869)
  • Cell & Developmental Biology  (2,681)
  • Temperatur
  • 42.75
  • AERODYNAMICS
  • 1995-1999  (5,506)
  • 1925-1929  (207)
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  • 1
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    In:  Zoologische Mededelingen (00240672) vol.73, 1-11 (1999) p.187
    Publication Date: 2007-01-23
    Description: Menippus philippinensis Jacoby, 1894, is reported from Java, and Issikia clarki (Jacoby, 1884) comb. nov., from Sumatra.
    Keywords: Coleoptera ; Chrysomelidae ; Galerucinae ; Menippus ; Issikia ; Issikia clarki ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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  • 2
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    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.101
    Publication Date: 2007-01-26
    Description: Galeruca malakkana spec. nov., a new species is described from Malaysia.
    Keywords: Coleoptera ; Chrysomelidae ; Galerucinae ; Galeruca ; new species ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 3
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.143
    Publication Date: 2007-01-10
    Description: New and old records of the robberfly Machimus cowini in the Netherlands (Diptera: Asilidae) Until recently, Machimus cowini (Hobby, 1943) was known from just one record in the Netherlands. An examination of Dutch specimens of the similar M. cingulatus revealed specimens of M. cowini from five new localities. The records are concentrated on the island Ameland and along the rivers Waal and Maas. On Ameland, M. cowini probably occurs in coastal dunes. Near Nijmegen the species was found in grassy vegetation on floodplains and on riverdunes near the river.
    Keywords: Insecta ; Diptera ; Asilidae ; Machimus cowini ; Nederland ; Verspreiding ; Biotopen ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 4
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    In:  Zoologische Mededelingen (00240672) vol.73, 1-11 (1999) p.1
    Publication Date: 2007-01-23
    Description: Two new species of the genus Diachasmimorpha Viereck, 1913 (Braconidae: Opiinae) are described: D. feijeni spec. nov. from Bhutan (reared from Bactrocera minax (Enderlein) (Diptera: Tephritidae) in fruits of Citrus reticulata Blanco (mandarin)) and D. budrysi spec. nov. from Far East Russia. A key to the Palaearctic species is added, including two similar species (Fopius alternatae (Tobias, 1977), and F. myolejae (Tobias, 1977)).
    Keywords: Hymenoptera ; Braconidae ; Opiinae ; Diachasmimorpha ; Palaearctic ; Bhutan ; Russia ; key ; Diptera ; Citrus reticulata ; Bactrocera minax ; Tephritidae ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 5
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    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.105
    Publication Date: 2007-01-23
    Description: A new genus of the subfamily Alysiinae (Braconidae) is reported from South Africa (Bobekoides gen. nov.; type species: Bobekoides fulvus spec. nov.), illustrated, and described. A key to the species is added. The new genus is closely related to the East Palaearctic genus Hylcalosia Fischer, 1967.
    Keywords: Hymenoptera ; Braconidae ; Alysiinae ; Alysiini ; Bobekoides ; Afrotropical ; South Africa ; key ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 6
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    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.1
    Publication Date: 2007-01-23
    Description: A synopsis of the genus Rhodopygia Kirby is given. Its species are discussed and their diagnostic morphological characters elucidated by figures. The hitherto unknown females of R. hinei Calvert and R. pruinosa Buchholz are described. A key to the species is provided.
    Keywords: Libellulidae ; Rhodopygia ; Central and South America ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 7
    Publication Date: 2007-01-23
    Description: For the first time a gregarious parasitoid belonging to the genus Phaenocarpa Foerster, 1862 (Braconidae: Alysiinae) is reported, and described as P. helophilae spec. nov. from England. The first record of Chloropidae as host for a Phaenocarpa species is given; P. livida (Haliday, 1838) reared from Calamoncosis (Rhaphiopyga) glyceriae Nartshuk, 1958. Sathra debilis Foerster, 1862, is synonymised with P. livida (Haliday). Additionally, Phaenocarpa curticauda spec. nov. from The Netherlands is described and fully illustrated. A lectotype is designated for Alysia pectoralis Zetterstedt, 1838, and Phaenocarpa rufoflava Papp, 1968, is recognised as a valid species.
    Keywords: Hymenoptera ; Braconidae ; Alysiinae ; Alysiini ; Phaenocarpa ; Diptera ; Syrphidae ; Chloropidae ; Helophilus ; Calamoncosis ; Europe ; Palaearctic ; distribution ; biology ; gregarious ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 8
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.142
    Publication Date: 2007-01-10
    Description: Pemphredon montana, new to The Netherlands (Hymenoptera: Sphecidae) In 1998 Pemphredon montana Dahlbom, 1845 was recorded for the first time in the Netherlands. The species was found nesting in the insulating material of a caravan in the northernmost part of the province of Overijssel.
    Keywords: Insecta ; Hymenoptera ; Sphecidae ; Crabronidae ; Pemphredon montana ; Nederland ; Verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 9
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.140
    Publication Date: 2007-01-10
    Description: The influence of recent inundations on the distribution pattern of the isopod Eluma purpurascens in the province of Zeeland (Crustacea: Isopoda: Oniscoidea) Small scale mapping of Eluma purpurascens Budde-Lund, 1885 in the province of Zeeland revealed a remarkable distribution pattern. The species proved to be absent in parts which have been inundated during and after the second world war. This study shows that for the interpretation of distribution patterns the history of the study area should be considered.
    Keywords: Arthropoda ; Crustacea ; Isopoda ; Oniscoidea ; Nederland ; Verspreiding ; Biotopen ; Herkenning ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 10
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.33
    Publication Date: 2007-01-09
    Description: Faunistics and ecology of the syrphid genus Epistrophe in The Netherlands (Diptera: Syrphidae) Ten species of Epistrophe have been found in the Netherlands, two of which, E. cryptica and E. similis, are recorded here for the first time. The distribution, changes in distribution and ecology of the species were investigated and are illustrated by distribution maps and diagrams of the flight period. In all species, except E. eligans, females were observed more than males. Furthermore, females seem to be active later in the season than males. It is discussed that this is probably caused by the differences in behaviour between the males of the species.
    Keywords: Insecta ; Diptera ; Syrphidae ; Epistrophe ; Fenologie ; Verspreiding ; Biologie ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 11
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.1
    Publication Date: 2007-01-26
    Description: Until recently Boreus hyemalis was considered to be a rare species in The Netherlands. It was only known from a few localities in The Netherlands in the provinces of Noord-Holland, Zuid- Holland, Utrecht, Gelderland and Drenthe. The last few years many new populations have been discovered. In this paper the first records for the provinces of Limburg, Noord-Brabant and Overijssel are presented. The species seems to prefer scarcely vegetated patches in sanddunes, dominated by greyhair grass Corynephorus canescens and the moss Polytrichum piliferum. It proved to be relatively easy to find, when the right places were searched in the right period (October until February).
    Keywords: Insecta ; Mecoptera ; Boreidae ; Boreus hyemalis ; Sneeuwspringer ; Verspreiding ; Nederland ; Biotopen ; Biologie ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 12
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.79
    Publication Date: 2007-01-10
    Description: Het genus Bryotropha in Nederland (Lepidoptera: Gelechiidae) Het genus Bryotropha staat bekend als een notoir lastig geslacht van kleine bruine motjes. Die moeilijkheid komt door de variatie, maar vooral ook door gebrek aan bruikbare beschrijvingen. Met dit artikel zijn de negen Nederlandse soorten te determineren. Vanwege het gebrek aan determinatieliteratuur in heel Europa is het in het Engels geschreven. Behalve de maar één keer waargenomen B. domestica, zijn de meeste soorten vrij gewone verschijningen in ons land, zoals uit de kaarten blijkt.
    Keywords: Insecten ; Lepidoptera ; Gelechiidae ; Verspreiding ; Nederland ; Fenologie ; Waardplanten ; Biotopen ; Determinatiesleutel ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 13
    Publication Date: 2007-08-06
    Description: The occurrence of Digitivalva arnicella in the Netherlands: rediscovery and conservation (Lepidoptera: Plutellidae: Acrolepiinae) Digitivalva arnicella (Heyden, 1863), previously only known from two localities before 1902, has been rediscovered in eight localities in the northern part of the Netherlands (province of Drenthe) on its host Arnica montana. On the basis of leafmines, found in old herbarium collections, it can be concluded that the species was once widespread within the range of its host in the northern and eastern parts of the Netherlands and has apparently been overlooked by entomologists since. D. arnicella is a much endangered species in the Netherlands, because of the dramatic decline of its host. Two of the eight discovered populations have been lost since their discovery in the first half of the 1990’s. Systematics and life history of the species are described and illustrated, the distribution is mapped and advise for management of its sites are given. The current management of some populations of Arnica, by mowing the site completely in August, is disastrous for the young caterpillars, mining the leaves.
    Keywords: Acrolepiinae ; Plutellidae ; Yponomeutoidea ; Digitivalva ; Netherlands ; conservation ; Arnica ; Digitivalva arnicella ( Plutellidae- ) ; Habitat management ; Endangered status ; effect of food plant shortage ; conservation proposals ; Food plants ; Arnica montana ; effect on decline to endangered status ; Decline-to-endangered-status ; influences-and-conservation ; Netherlands ; Distribution ; population dynamics and conservation ; endangered species ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 14
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.91-93
    Publication Date: 2007-01-09
    Description: Nemobius sylvestris in the dunes near Bergen (Orthoptera) A large population of Nemobius sylvestris (Bosc, 1792) has been found in the dunes near Bergen (Noord-Holland), 60 km northwest of the nearest known site in the Gooi-area. This discovery sheds new light on a specimen from Bergen found in a collection, which was thought to be mislabelled.
    Keywords: Insecta ; Orthoptera ; Gryllidae ; Nemobius sylvestris ; Nederland ; Verspreiding ; Biotopen ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 15
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.85
    Publication Date: 2007-01-09
    Description: Interesting new records of Odonata in the Netherlands in 1998 A survey of the most interesting observations on Dutch Odonata is presented. During the Odonata Recording Scheme many new records of rare species have become available. Gomphus flavipes, G. vulgatissimus, Anax parthenope, Sympetrum pedemontanum and S. depressiusculum seem to become more common. The status of some threatened species is elucidated: Calopteryx virgo, Sympecma paedisca, Coenagrion hastulatum and Cordulegaster boltonii.
    Keywords: Insecta ; Odonata ; Verspreiding ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 16
    Publication Date: 2007-01-23
    Description: The assassin bug genus Rasahus Amyot & Serville (Heteroptera: Reduviidae: Peiratinae) comprises 26 Neotropical species. A cladistic analysis of the genus was carried out using 63 characters from external morphology, body vestiture, and male and female genitalia, with the species considered as terminal taxa. The analysis yielded 149 equally parsimonious cladograms, each with 206 steps, CI = 0.35, and RI = 0.60; the successive weighting procedure resulted in eight cladograms (CI = 0.79 and RI = 0.91). In the strict consensus cladogram, two major clades are delimited: one comprising the species R. rufiventris, R. hamatus, R. arcitenens, R. arcuiger, R. amapaensis, R. thoracicus, R. biguttatus, R. argentinensis, R. limai, R. grandis, and R. angulatus; and the other with R. castaneus, R. aeneus, R. scutellaris, R. maculipennis, R. brasiliensis, R. sulcicollis, R. surinamensis, R. albomaculatus, R. guttatipennis, R. atratus, R. peruensis, R. costarricensis, R. bifurcatus, R. flavovittatus, and R. paraguayensis. A cladistic biogeographic analysis of the provinces of the Neotropical subregion, considering distributional data of the species of Rasahus and three other genera of Peiratinae (Eidmannia, Melanolestes, and Thymbreus) was carried out. Four general area cladograms were obtained applying programs COMPONENT 2.0 and TASS. The most parsimonious general area cladogram (= implying fewer items of error) was obtained with COMPONENT 2.0 minimizing the number of leaves added, and shows the sequence (Desierto, (Caatinga, (Cerrado, (Chacoan, (Caribbean, Amazonian), (Paranaense, Atlantic))))). This sequence of area relationships is congruent with the history previously hypothesized for the subregion, where the development of an open vegetated diagonal (comprising the Chacoan, Cerrado, and Caatinga provinces) due to the aridification induced by the gradual uplift of the Andes, separated the former Amazonian forest in a northwestern part (Caribbean plus Amazonian provinces) and a southeastern part (Paranaense plus Atlantic provinces).
    Keywords: Cladistics ; biogeography ; Rasahus ; Heteroptera ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 17
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    In:  Zoologische Mededelingen (00240672) vol.72, 1-10 (1998) p.51
    Publication Date: 2007-01-26
    Description: Two new species of the genus Bentonia van Achterberg, 1992 (Braconidae: Orgilinae) (B. inca from Peru and B. xochiquetzalis from Mexico) are described and partly illustrated. A third undescribed species was found for which some characters are listed. The distribution of B. scutellaris van Achterberg, 1992, is extended west to Peru and B. longicornis van Achterberg, 1992, north to Venezuela. An identification key is added.
    Keywords: Braconidae ; Orgilinae ; Bentonia ; Peru ; Mexico ; Venezuela ; key ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 18
    Publication Date: 2007-01-23
    Description: The West Palaearctic species of the subfamily Paxylommatinae are reviewed and the species of the genus Hybrizon Fallén, 1813, from the Palaearctic region are keyed. Hybrizon juncoi (Ceballos, 1957) is recognized as a valid species, a neotype is designated for Hybrizon latebricola Nees, 1834, and a lectotype is designated for Plancus apicalis Curtis, 1833. Paxylomma grandis Rudow, 1883, Ogkosoma schwarzi Haupt, 1913, and Eurypterna arakawae Matsumura, 1918, are new junior synonyms of Eurypterna cremieri (de Romand, 1838).
    Keywords: Ichneumonidae ; Paxylommatinae ; Hybrizon ; Ghilaromma ; Eurypterna ; keys ; distribution ; Palaearctic ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 19
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.29
    Publication Date: 2007-01-10
    Description: Het genus Scrobipalpa in Nederland (Lepidoptera: Gelechiidae) Scrobipalpa is een geslacht van kleine, lastig uit elkaar te houden motjes. In heel Europa zijn ongeveer 70 soorten bekend. Doorgaans zijn de vleugels bruin- of grijsachtig met een tekening van stippels en strepen die bovendien erg kan variëren. Hierdoor kunnen de individuele soorten vaak moeilijk herkend worden. Aan de hand van de genitaliën kunnen soorten wel allemaal gedetermineerd worden. Omdat de literatuur over deze groep niet erg toegankelijk is en bestaande beschrijvingen soms erg onvolledig zijn, wordt dit artikel in het Engels geschreven. Met dit artikel zijn de elf Nederlandse soorten te determineren. De meeste hiervan zijn min of meer gebonden aan de kust. Van alle soorten worden naast beschrijvingen van de vleugeltekening en de genitaliën, ook de verspreiding, de biologie en de ecologie gegeven.
    Keywords: Insecta ; Lepidoptera ; Scrobipalpa ; Verspreiding ; Biotopen ; Fenologie ; Herkenning ; Determinatiesleutel ; Waardplanten ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 20
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.93
    Publication Date: 2007-01-09
    Description: New records of Cheilosia caerulescens in the Netherlands (Diptera: Syrphidae) Cheilosia caerulescens is a rare hoverfly in The Netherlands. Until 1998 only four records were known, the first in 1986. In 1998 the species was found on three new and one old locality. The record from Heemstede (province of Noord-Holland) is among the northernmost in the European distribution of this species. Three of the four records originate from gardens.
    Keywords: Insecta ; Diptera ; Syrphidae ; Cheilosia caerulescens ; Nederland ; Verspreiding ; Biotopen ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 21
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.89
    Publication Date: 2007-01-09
    Description: Chironomidae in newly created nature reserves In a newly created nature reserve near Eindhoven many interesting species of Chironomidae were found. Several new species to the Dutch fauna were identified and one species (of the genus Neozavrelia) proved to be new to science. The fauna of these young habitats is poorly known, but proves to be very interesting.
    Keywords: Insecta ; Chironomidae ; Verspreiding ; Biotopen ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 22
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    In:  Zoologische Mededelingen (00240672) vol.73, 1-11 (1999) p.165
    Publication Date: 2007-01-23
    Description: A key to the European species of the Pteromalus altus group is presented. The relationship between this group and species of the genus Euphorbia (Euphorbiaceae) is confirmed. One new species: P. villosae, associated with Euphorbia villosa Waldst. & Kit.is presented. Two new species of the albipennis group: Pteromalus almeriensis and P. costulata are presented. In addition one species of the P. vibulenus group: P. tethys is added. Information on P. sylveni Hedqvist, P. osmiae Hedqvist and P. discors Graham is given.
    Keywords: Chalcidoidea ; Pteromalidae ; Pteromalus ; new species ; redescriptions ; Spain ; Portugal ; France ; Greece ; Euphorbia ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 23
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    In:  Zoologische Mededelingen (00240672) vol.73, 1-10 (1999) p.131
    Publication Date: 2007-01-23
    Description: The species of Encarsia Foerster (Hymenoptera: Aphelinidae) known from Egypt are revised. A total of 14 species are treated, including one new species. E. indifferentis Mercet, 1929, is synonymised with E. inaron (Walker, 1839). All species are fully described or diagnosed, and illustrated. Host records, and species-distributions outside Egypt, are given.
    Keywords: Egypt ; Encarsia ; Aleyrodidae ; Aphelinidae ; Diaspididae ; parasitoids ; biological control ; natural enemies ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 24
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.133
    Publication Date: 2007-01-10
    Description: Interesting records of beetles in The Netherlands (Coleoptera: Staphylinidae, Nitidulidae, Dermestidae) Tachyporus quadriscopulatus Pandellé, 1869 has been recorded for the second time in the Netherlands at Arcen and Velden, province of Limburg. After 27 years, a third record of Carpophilus marginellus Motschulsky, 1858 can be reported from St. Geertruid, in the southern part of the province of Limburg. One specimen was found outdoors, in a wood. One specimen of Anthrenocerus australis Hope, 1843 was also found outdoors, in Oost- Maarland also in southern Limburg, sitting on a flower in a meadow.
    Keywords: Insecta ; Coleoptera ; Staphylinidae ; Nitidulidae ; Dermestidae ; Nederland ; Verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 25
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.127
    Publication Date: 2007-01-10
    Description: Butterflies in the Netherlands still under pressure (Lepidoptera: Rhopalocera) New information on the Dutch Rhopalocera fauna since the distribution atlas of Tax (1989) is presented. Coenonympha pamphilus was common in large parts of the Netherlands, but has declined dramatically. C. arcania is now formally extinct in our country. An extensive research showed that Maculinea alcon ericae has dissappeared from many sites. Furthermore the smallest of the two remaining populations of Heteropterus morpheus seems to have gone extinct. On the other hand, Callophrys rubi, has colonized new territory. Lampidus boeticus, was observed once as an adult and once a caterpillar was found between snow peas from Egypt. Colias croceus was very abundant in 1998. The reintroductions of Maculinea teleius and M. nausithous in 1990 appear to have been successful.
    Keywords: Insecta ; Lepidoptera ; Rhopalocera ; Verspreiding ; Bedreiging ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 26
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.9 (1999) p.109
    Publication Date: 2007-01-10
    Description: The rearing of the botfly Cephenemyia auribarbis (Diptera: Oestridae) After several failures we finally succeeded in rearing botflies Cephenemyia from third-instar larvae. From a red deer shot at 13 March 1998 about one hundred larvae of Cephenemyia auribarbis (Meigen, 1824) were collected. Ten individuals reached the pupal stage. After 22 days, one fullgrown male died in the pupa, and two males emerged and lived for 17 and 18 days respectively. This is one of the few recorded succesful attempts to rear botflies.
    Keywords: Insecta ; Diptera ; Oestridae ; Cephenemyia auribarbis ; Nederland ; Verspreiding ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
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  • 27
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.90
    Publication Date: 2007-01-09
    Description: A new record of Chorthippus apricarius in the Netherlands (Orthoptera) Chorthippus apricarius is a very rare grasshopper in The Netherlands. Only three, very widely separated sites are known. In 1998 a small new population has been found in a roadside verge, 2 km southwest of the southernmost site in the south of the province of Limburg.
    Keywords: Insecta ; Orthoptera ; Acrididae ; Chorthippus apricarius ; Locomotiefje ; Verspreiding ; Biotopen ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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    In:  Nederlandse Faunistische Mededelingen (01692453) vol.8 (1999) p.11
    Publication Date: 2007-01-09
    Description: Checklist of the Nitidulidae and Brachypteridae (Coleoptera) of the Netherlands and surrounding regions An annotated checklist of the Nitidulidae and Brachypteridae of the Netherlands and surrounding regions is presented, based mainly on literature research. Since the list of Brakman seven new species to the Netherlands have been published. One of these species, Pocadius adustus, is listed here for the first time. Major nomenclatorial changes, published elsewhere, have been implemented. The list contributes to the faunistic work of the European Invertebrate Survey - The Netherlands. A separate list of hostplants of the Nitidulidae and Brachypteridae is presented.
    Keywords: Insecta ; Coleoptera ; Nitidulidae ; Brachypteridae ; Glanskevers ; Verspreiding ; Waardplanten ; Biologie ; Naamlijst ; Nederland ; 42.75
    Repository Name: National Museum of Natural History, Netherlands
    Type: Article / Letter to the editor
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    Journal of molecular evolution 41 (1995), S. 238-246 
    ISSN: 1432-1432
    Keywords: Cellular slime molds ; Animals ; Fungi ; Plantae ; Maximum-likelihood method ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phylogenetic position of Dictyostelium inferred from 18S rRNA data contradicts that from protein data. Protein trees always show the close affinity of Dictyostelium with animals, fungi, and plants, whereas in 18S rRNA trees the branching of Dictyostelium is placed at a position before the massive radiation of protist groups including the divergence of the three kingdoms. To settle this controversial issue and to determine the correct position of Dictyostelium, we inferred the phylogenetic relationship among Dictyostelium and the three kingdoms Animalia, Fungi, and Plantae by a maximum-likelihood method using 19 different protein data sets. It was shown at the significance level of 1 SE that the branching of Dictyostelium antedates the divergence of Animalia and Fungi, and Plantae is an outgroup of the Animalia-Fungi-Dictyostelium clade.
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    Journal of molecular evolution 42 (1996), S. 183-193 
    ISSN: 1432-1432
    Keywords: Small-subunit ribosomal RNA ; Phylogeny ; Animals ; Fungi ; Plants ; Alveolates ; Heterokonts ; Stramenopiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolutionary relationships of four eukaryotic kingdoms—Animalia, Plantae, Fungi, and Protista—remain unclear. In particular, statistical support for the closeness of animals to fungi rather than to plants is lacking, and a preferred branching order of these and other eukaryotic lineages is still controversial even though molecular sequences from diverse eukaryotic taxa have been analyzed. We report a statistical analysis of 214 sequences of nuclear small-subunit ribosomal RNA (srRNA) gene undertaken to clarify these evolutionary relationships. We have considered the variability of substitution rates and the nonindependence of nucleotide substitution across sites in the srRNA gene in testing alternative hypotheses regarding the branching patterns of eukaryote phylogeny. We find that the rates of evolution among sites in the srRNA sequences vary substantially and are approximately gamma distributed with size and shape parameter equal to 0.76. Our results suggest that (1) the animals and true fungi are indeed closer to each other than to any other “crown” group in the eukaryote tree, (2) red algae are the closest relatives of animals, true fungi, and green plants, and (3) the heterokonts and alveolates probably evolved prior to the divergence of red algae and animal-fungus-green-plant lineages. Furthermore, our analyses indicate that the branching order of the eukaryotic lineages that diverged prior to the evolution of alveolates may be generally difficult to resolve with the srRNA sequence data.
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    Machine vision and applications 8 (1995), S. 187-193 
    ISSN: 1432-1769
    Keywords: Tracking ; Segmentation ; Pigs ; Animals ; Computer vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract An algorithm was developed for the segmentation and tracking of piglets and tested on a 200-image sequence of 10 piglets moving on a straw background. The image-capture rate was 1 image/140 ms. The segmentation method was a combination of image differencing with respect to a median background and a Laplacian operator. The features tracked were blob edges in the segmented image. During tracking, the piglets were modelled as ellipses initialised on the blobs. Each piglet was tracked by searching for blob edges in an elliptical window about the piglet's position, which was predicted from its previous two positions.
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    Journal of agricultural and environmental ethics 10 (1997), S. 249-267 
    ISSN: 1573-322X
    Keywords: Animals ; Asia ; consciousness ; Australia ; Hong Kong ; India ; Israel ; Japan ; New Zealand ; The Philippines ; Russia ; Singapore ; Thailand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The interactions between humans, animals and the environment have shaped human values and ethics, not only the genes that we are made of. The animal rights movement challenges human beings to reconsider interactions between humans and other animals, and maybe connected to the environmental movement that begs us to recognize the fact that there are symbiotic relationships between humans and all other organisms. The first part of this paper looks at types of bioethics, the implications of autonomy and the value of being alive. Then the level of consciousness of these relationships are explored in survey results from Asia and the Pacific, especially in the 1993 International Bioethics Survey conducted in Australia, Hong Kong, India, Israel, Japan, New Zealand, The Philippines, Russia, Singapore and Thailand. Very few mentioned animal consciousness in the survey, but there were more biocentric comments in Australia and Japan; and more comments with the idea of harmony including humans in Thailand. Comparisons between questions and surveys will also be made, in an attempt to describe what people imagine animal consciousness to be, and whether this relates to human ethics of the relationships.
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    Journal of Morphology 40 (1925) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Morphology 40 (1925), S. 517-557 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An early segregation of germ cells and migration through a germ track into the gonad does not occur in the albino rat. The germ cells are produced only from the peritoneum of the genital region and their earliest formation is coincident with the thickening of the coelomic epithelium to form the genital ridge. This takes place eleven days after insemination in embryos of approximately 18 somites. Germ cells continue to form from the peritoneum during the early development of the gonad. The peritoneum of this region also produces mesenchyme, smaller cells of the gonads, and the germinal epithelium.The argument for the specific character of the germ cells in vertebrates and their continuity from the egg is based largely upon assumption, and not upon substantial observations, and must be discarded. Germ-cell origin is a problem of cellular differentiatio, and not of early segregation.
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    Journal of Morphology 41 (1925), S. ii 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Journal of Morphology 41 (1925), S. 191-216 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Painted turtles, gopher tortoises, and terrapins were fed on various mixtures of sand, salts, dextrin, casein, cod-liver oil, wheat, eggs, lettuce, and meal worms. Each individual was weighted weekly for about a year and then killed for analysis, the water, ash, nitrogen, and fat being determined. Some individuals increased in weight as much as 75 per cent, others lost weight. Judged by growth and chemical analyses, the food requirements of chelonians, as representative poikilothermal vertebrates toward nutritive substances (including vitamines) are similar to those of homoiothermal animals.
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    Journal of Morphology 41 (1925), S. 267-281 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Of the eggs laid by Fasciolaria about 1 per cent develop into veligers, about 2 per cent more undergo a few cleavage divisions, and about 97 per cent do not divide at all. The 99 per cent that fail to develop normally are ‘swallowed’ by the veligers. This study concerns itself chiefly with the ova that do not divide. Notes on normal development and on the ova that undergo atypical cleavage are included.All of the ova are found to be typical when passed from the ovary. To each ovum one to several sperms become attached at the vegetal pole in the region of a mass of undifferentiated protoplasm - the ‘polar mass.’ A fertilization cone forms in each ovum and a fertilization membrane. In typical development a yolk lobe is formed, the sperm enters in the usual way, and fertilization is completed as in many other mollusks. In 97 per cent of the ova the yolk lobe is not formed and the sperm does not enter. In these cases the wall of the egg nucleus remains intact a long time. The nucleus itself and the ‘polar mass’ sink into the egg and meet at the center. Then the nuclear wall disappears and an atypical diaster is formed. However, cleavage is not begun and the chromosomes form vesicles that remain near the center of the ovum until it is ‘swallowed’ and digested by the veliger.
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The blood of Perophora viridis is found to contain six types of cells: (1) Green cells, which have green-colored fatty bodies embedded in clear cytoplasm. (2) Orange cells, with orange-colored bodies of unknown composition in the cytoplasm. (3) Colorless berry-like cells, with fluid-filled vesicles in the cytoplasm. (4) Granular amoeboid cells. (5) Compartmental amoeboid cells, which have box-like vacuoles containing brownian granules of a fatty substance. (6) Vesicular, signet-ring type of cell having a single large vacuole. The cytological structure of these cells and their reaction to various dyes are described.An effort has been made to homologize the types of cells found in the blood of other ascidians with those found in Perophora.It is concluded that the variety of colors found in the cells of ascidian blood is due to the varying chemical states of the vanadium-containing chromogen present in the cells.
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    Journal of Morphology 42 (1926) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Morphology 42 (1926), S. 111-141 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Disintegration in killing agents was studied throughout development. In the unfertilized egg and cleavage stages the death gradient runs from animal to vegetal pole. In the late blastula stage the future dorsal surface and future point of gastrulation show heightened susceptibility. The gastrula has a gradient from anterior to posterior end along its dorsal surface, with a slight reverse gradient around the blastopore; lateral and ventral regions are least susceptible.Before and after the appearance of the neural groove, the dorsal surface shows increased susceptibility with gradient in it from anterior to posterior end. The neural tube is highly susceptible, with a death gradient from anterior to posterior end and a slight reverse gradient at its posterior end.During late stages and in the larva the double gradient is present; death begins at the two ends and progresses backward from head, forward from anus; from the former most rapidly. The least susceptible place is near the posterior end. The posterior reverse gradient is less developed in the lamprey than in other vertebrate embryos, due, probably, to its lack of a tail bud.Assuming that death differences indicate differences in rate of activity, it appears that such differences in activity may be causes and not results of developmental processes, for the development of certain parts (dorsal surface, blastopore, central nervous system) is indicated by heightened activity before it is evident morphologically.
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    Journal of Morphology 42 (1926), S. 83-109 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The summary of this paper is as follows:1A critical review of the developmental evidence shows that the branchial pouches are formed in cephalocaudal sequence subsequently to the segmentation of the dorsal mesoderm.2The pouches interrupt a continuous sheet of mesoderm to form the branchial arches.3The arches when formed do not correspond topographically to the dorsal somites.4Branchiomerism does not therefore coincide with somitic metamerism.3The branchial structures do not support the theory of head segmentation.3The nervi trigeminus, facialis, glossopharyngeus, and vagus cannot be regarded as segmental nerves.3There is no evidence that branchial pouches or arches have been elided from the series.3The problem of meristic homology is briefly discussed.
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    Journal of Morphology 43 (1927), S. 521-546 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The literature on the general subject of freezing and survival both in plants and in animals is briefly reviewed and a bibliography given. Insects representing three ecological groups, (1) the oak borers - exposed to temperature extremes normally; (2) stored-products insects representing supposedly a tropical or subtropical group, and, (3) aquatic insects never exposed to temperatures lower than 0°C., were chosen for this study. Determinations of the freezing and undercooling points were made during the yearly cycle.Both the stored-products insects and the aquatic insects studied showed no periodicity in freezing or undercooling. The oak borers showed marked periodicity. The freezing-point varies directly with the moisture content. Cold-hardiness was produced experimentally by, (1) exposure of insects to low temperatures and, (2) by dehydration. Loss of cold-hardiness was produced experimentally by combinations of high temperature, food, and high relative humidity. The freezing-point ordinarily found corresponds with that of the blood. Repeated freezings of the same insect or tissue showed no hysteresis. There exists in certain insects a secondary freezing-point below that ordinarily found. Oak borers in summer condition die at the first freezing-point; in fully hardened condition they die at the secondary freezingpoint.
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    Journal of Morphology 44 (1927), S. 1-20 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ant Formica exsectoides F. builds mounds with some reference to sunlight, and measurements of internal temperatures have shown them higher in upper parts of the mound, but different in different faces of the mound - all higher than the earth outside the mound.Inside temperatures are not constant; they are due to the sunshine. The mound is so fabricated that the internal temperatures are conserved during the night. The ants make use of the differential internal temperatures for rearing broods.Some mounds show bilateral symmetry dependent upon sun exposure.Measurements of rate of running of these ants show a falling off with lower temperatures, and possibly this is one factor in the smaller development of northerly aspects of these mounds.
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    Journal of Morphology 44 (1927), S. 117-125 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the early cleavage stages of Ascaris the homologous chromosomes are of unequal length. Measurements show that these homologues fall into two sharply defined groups suggesting their biparental origin. The shorter are considered to have come from the male.As the age of the embryo increases, these differences between the chromosome mates tend to become less, and it is suggested that at some later period in the history of the animal this difference will entirely disappear in response to the effect of continued existence in a common environment. The length of the chromosomes is very slightly shortened during the early cleavage divisions, while the area of the equatorial cross-section of the cells becomes enormously reduced.
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    Journal of Morphology 44 (1927), S. 313-339 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The rates of oxygen consumption of single pupae of blowflies (Phormia terraenovae, Phormia regina, Lucilia sericata), of the flesh fly (Sarcophaga sarracenioides Aldrich), of the Mediterranean flour moth (Ephestia kuehniella), and of the bee moth (Galleria mellonella) during metamorphosis, until emergence, have been determined. The record for each pupa, with the exception of those of blowflies, is practically continuous day and night during the period of pupal development which lasted from 140 to 300 hours, according to the species, at the temperatures used. During pupal development there is first a period of decrease in rate, which is later followed by a steady increase until a short time before emergence, when a sudden decrease occurs.The ‘oxygen curves’ of the blowfly pupae (Diptera) are quite different from those of the flour-moth and bee-moth pupae (Lepidoptera), although all are of the same general U-shaped type. There are strong indications of a specific difference in the curves of the blow-fly pupae. The flour-moth pupae curves differ slightly from those of the bee-moth pupae. During the major part of development the rates of O2 consumption of pupae of both sexes of bee moth and flour moth are about the same, but near the end of metamorphosis the females have higher rates than the males. No such sex difference appears among the dipterous pupae used.
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    Journal of Morphology 44 (1927), S. 363-372 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The history of investigations on the contractile vacuole is reviewed briefly and brought up to date.The study of the contractile vacuole in Amoeba proteus is considered from standpoints of origin, structure, behavior, and function. The results are obtained from a prolonged study of normal organisms and from their reactions when introduced into conductivity water.The origin of vacuoles is studied by means of dark-field illumination which reveals the vacuole to be formed from a fusion and coalescence of extremely minute droplets.The retaining ‘wall’ of the contractile vacuole is not a permanent structure, but is in the nature of a condensation membrane, totally disappearing with each contraction.The loci of the contractile vacuoles are not permanent, but vacuoles are formed more or less at random. It is unlikely that they are supported in gelated areas, for amoebae with a dozen vacuoles are quite active and there is no interference with amoeboid movement.Conductivity water increases the size, number, and rate of contraction of contractile vacuoles, which suggests that they may function in maintaining an osmotic gradient as well as in the elimination of metabolic waste.
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    Journal of Morphology 44 (1927), S. 467-514 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The eggs of Corella develop in the atrial chamber of the parent at a pH below that of normal sea-water (pH 7.4 ±). When removed to normal sea-water in early stages and under certain other experimental conditions, larval development is more or less inhibited, the tail being most inhibited, the dorsal region somewhat less. The free larval stage may be eliminated and later development and metamorphosis may proceed normally to an advanced stage in the chorion and give rise to normal ascidians. The region most inhibited are, in general, those which possess the highest reducing power, as indicated by KMnO4. Experiments made in the attempt to control development all agree in indicating that the early stages are adjusted to a certain CO2 concentration approximately that of the atrial chamber and presumably near that of the body. Solutions of the same pH may or may not inhibit development according to their CO2 content.The tail, the region of highest reducing power in the embryo during its development, is most inhibited; the dorsal region, the next most rapidly reducing region, is next in degree of inhibition. All differences in reducing power disappear when, or soon after, the animals are killed by other agents before treatment with KMnO4.
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    Notes: The claspers of Centrina are adnate with the pelvic fin and bear a spine as in other Spinacidae. Mustelus canis resembles M. lunulatus rather than M. vulgaris. The claspers of Chiloscyllium end in a pointed spike. Pseudotriakis resembles the Carchariidae. The three North American Atlantic species of the genus Raia are considered, and R. laevis and R. erinacea are placed in the pseudogenus containing R. batis, and a new pseudogenus erected for R. ocellata. A gross and histological account is given of the Cowper's glands of Homo, and they are shown to be homoplastic with clasper glands, similar in structure, arrangement, development, and function.
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    Notes: In the golden-mantled ground-squirrel, Callospermophilus, a spatulate glandular area has been noted in the skin of the back. It has been found in the following species: C. l. lateralis, C. l. arizonensis, C. l. caryi, C. l. saturatus, C. l. tescorum, C. c. chrysodeirus, and C. bernardinus. Probably it is common to the genus.The individual glands making up this area are modified and enlarged sudoriparous glands. They are divided into a tightly coiled and branched fundus, a large sinus, and a duct which passes caudad and outward to its exit at the surface.The glands secrete a strongly smelling oil, which is probably left on vegetation and other objects in the animal's environment and serves as a source of information to other members of the species. The glands are more active in spring and summer than in winter. They are stimulated by excitement. While present in both sexes, both adult and juvenile, they are best developed in adult males.Callospermophilus has three anal glands. These have flat-topped, straight-sided nipples which are protruded from the anus if the animal is frightened. A milky substance with a very weak odor can be extruded.
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    Notes: The study is divided into three parts. Part I deals with the chromosome number and morphology in the amniotic cells of rabbit embryos. The number of chromosomes has been found essentially constant in amniotic cells of young, but more variable in older embryos. The somatic number is 44. Part II deals with the chromosomes of race crosses (Flemmish Giant X Polish) in which the homologous chromosomes were found to be alike. Part III deals with spermatogenesis. There are forty-four chromosomes in spermatogonia, and twenty-two in primary spermatocytes. The sex chromosomes are of the usual X-Y type.
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    Notes: 1Monovalent cation salts induce reversal in the direction of the stroke of the cilia; bivalent and trivalent cation salts with a few exceptions do not. Some acids induce reversal, others do not.2The duration of reversed action varies with the kind of salt and with the concentration. As the concentration increases, the duration of reversed action increases to a maximum and then decreases to zero.3Bivalent and trivalent cation salts neutralize the effect of monovalent cation salts. The relative amount required varies with the kind of salt used and with the concentration.4The amount of a given salt required to neutralize another salt is not proportional to the concentration of the salt neutralized. Weber's law does not hold.5The results seem to indicate that ciliary reversal is associated with differential adsorption and consequent changes in electric potential, but that there are also other factors involved.
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    Notes: A special type of cell, called ‘Lichtzellen’ by Hesse, was found in the photosensitive regions of the earthworm. Wherever the epidermis is most sensitive to light these cells are most abundant. They are found in the epidermis of all segments of the body and also in nerve enlargements of the prostomium and the caudal segment, but the intersegmental and ventral regions of the different segments, except the more distal ones, contain none of them. They are supplied by nerves and each contains a characteristic inner structure, the optic organelle, composed of a large central hyaline structure, the lens, which is surrounded by a dense network of nerve fibrillae, the retinella. In hanging drops the lens was found to focus light in the region of the retinella irrespective of the direction of the rays.These cells are similar in structure and function to the visual cells in leeches. Available data indicate that these cells function as photoreceptors and that the fibrillae of the retinella are the direct receptors of light stimuli.Pigment is not associated with the photoreceptors in a way that suggests direct functional relationship, but there is a subepidermal pigment layer through which pinhole windows admit light along the path of nerves to each of the nerve enlargements containing photoreceptor cells. These windows open in such directions as to determine the direction of withdrawal of the worm.
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    Notes: The effect of removal of the liver has been noted in fishes, frogs, and turtles. As in the higher vertebrates, removal of the liver produced a fall in blood sugar and a loss in muscular tone. The lower vertebrates failed to respond to intravenous injections of glucose, as do the birds and mammals. They also fail to respond to maltose or levulose. The liver maintained the blood-sugar level in the lower vertebrates, which is necessary for the maintenance of life.The mechanism of carbohydrate metabolism in the lower vertebrates may be different from that in the higher ones, in that glucose, when injected intravenously, apparently exercises a progressively less beneficial effect on the characteristic hypoglycemic condition which follows the removal of the liver of mammals and cold-blooded vertebrates.
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    Journal of Morphology 41 (1925), S. 239-265 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper reports experiments with Fundulus heteroclitus to modify larval development by means of ultraviolet radiation. Eggs were exposed to radiation at various intervals after fertilization for varying periods of time. The results accord with previous work on fish teratology, and the developmental types obtained are essentially similar to those produced by chemicals, cold, and hybridization. The deviations from normal development occur in the same body regions as do those in other vertebrates whose early development has been modified by the action of radiation (x-rays, radium, etc.).The results of these experiments indicate that there is a non-specificity in susceptibility relations with the production of similar types of monsters for widely different reagents. That these eggs are differentially susceptible to the action of ultraviolet radiation is indicated by the fact that those regions which have the highest metabolic activity when an inhibiting influence is active are the ones most generally affected. Thus modifications of the nervous system, sense organs, circulatory system, tail region, and body axis result, respectively, in the production of varying degrees of cyclopia, inadequate circulation, short, stubby or bent, non-motile tails (some bifid), and anterior twinning.As these modifications may be produced by applying inhibiting influences during the first few minutes after fertilization, it is evident that there is in the egg at this stage some constitutional or physiological basis which determines early differences in susceptibility of its various parts.
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    Journal of Morphology 41 (1926), S. 427-439 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Webbing of toes or fingers in man is produced by a local arrest of development, causing retention of the normal embryonic webbing. This type of digital fusion involves only the skin, the skeleton being unaffected. The extensor tendons of the toes may sometimes be fused.Webbed digits occur normally in some marsupials, rodents, and insectivores, in a number of lemurs and catarrhines, and in the siamang and gorilla. They also may occur in varying degree in other Primates, notably Hylobates. An analysis of five new pedigrees together with those already published demonstrates that webbing of toes in man may be inherited in either a mendelian or sex-linked manner. In one case this character follows the course of the Y-chromosome.
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    Journal of Morphology 45 (1928) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Amoeba proteus was raised in a modified and diluted Ringer solution. When the pH of this culture medium became less than 6.0, the normal activities of the amoebae were interfered with; and when a still lower pH was attained, the amoebae died off. The same was true when the pH became greater than 8.0. At neutrality the activities were subnormal, very dark, and rounded. The rate of locomotion of amoebae raised in solutions with a pH less than 7.0 showed a maximum rate of locomotion at pH 6.6, which decreased as the pH changed in either direction, dropping to a very low rate at pH 7.0 and above and also below 6.0. For amoebae raised at a pH above 7.0 the rate was maximum at pH 7.6 and decreased as the pH changed in either direction; it was low at pH 7.0 and below and also above 8.0.On increasing the external osmotic pressure of the medium it was found that the effects caused varied somewhat with the hydrogen-ion concentration. Small increases in osmotic pressure decreased the rate from the normal at pH 6.0 and 8.0, increased it at pH 6.6 and 7.6, and did not affect it at pH 7.0. Osmotic pressures above that produced by M/20 lactose caused locomotion to cease in a short time at all pH values.
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    Journal of Morphology 45 (1928), S. 209-231 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The highly specialized cranial musculature of the toadfish is characterized by the following features: 1Absence of intermandibularis and branchiomandibularis muscles.2Presence of levator premaxillaris muscle.3Very large branchial chamber, the outer wall of which is formed by seven branchiostegal rays connected by a strong fascia provided with muscles (oblique levators and adductors).4Highly developed masticator muscles (adductor mandibularis and pterygoids).5The rectus abdominis, sternohyoid, and hyohyoid muscles are attached by a median aponeurosis to the hyoid and basibranchial elements and directly to the hypobranchial cartilages; this muscle complex depresses the buccal floor in opposition to the geniohyoid.6The pelvic fins are in the jugular position.7Two narrow muscles connect the cleithrum with the fourth ceratobranchial.8The cranial musculature is obviously adapted to a carnivorous habit and particularly for increasing respiratory capacity under asphyxial conditions.
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    Journal of Morphology 45 (1928), S. 293-398 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Blindfolded persons walk, run, swim, row, and drive automobiles in clock-spring spiral paths of greater or less regularity when attempting a straightaway. The spirals turn either right or left in one and the same individual, and may do so even in one experiment. But either right or left turns predominate in the great majority of individuals, often to a high degree. The paths show marked individuality, and there is some ground for thinking there exists a correlation between temperamental differences and general character of path.The mechanism which produces the spiral path is not located in the locomotor organs, but in the central nervous system and is probably identical essentially with the spiral mechanism in other motile organisms, all of which move in spiral paths when there are no guiding senses to direct the path. The clock-spring spiral in man is interpreted as the expression in two dimensions of space of a helical spiral mechanism which seems to exist in all motile organisms moving in three dimensions of space and in amebas which move in two dimensions. In a large number of lower organisms the number of body lengths per spiral turn is almost constant, being about 4.5. The smallest regular swimming spirals in man are very close to this value, but the smallest regular walking spirals are somewhat larger. The fundamental spiral mechanism seems to be of molecular dimensions, and there seems to exist a demonstrable locomotor bilateral asymmetry in very nearly, if not quite, all organisms.
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    Journal of Morphology 45 (1928), S. 473-503 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: A detailed study has been made of the anatomy of one of the fingernail shells, and preliminary observations on the life-history have been carried out. In its general organization Sphaerium notatum is very similar to the larger fresh-water lamellibranchs. A gastric shield, crystalline style, and style sac, very similar to those found in the stomach and intestine of Lampsilis, are present. A pair of slender muscles extending from the dorsal side of the body into the gills, and evidently not previously described, have been found. The nervous system consists of the typical three pairs of lamellibranchiate ganglia, with their connectives, accessory ganglia, and nerve fibers. Particular study was given to the statocysts and osphradia, and attention is called to the fact that the function commonly ascribed to the osphradia is incompatible with their position in the roof of the cloacal chamber.S. notatum, like all the Sphaeriidae, is hermaphroditic and viviparous. The gonads are paired racemose glands lying behind and below the stomach. The sperm-producing follicles form the anterior portion of each gonad and are somewhat smaller and more numerous than the ova-producing follicles which form the posterior portion. The young pass through the early stages of development in brood pouches in the gills and are expelled as relatively enormous individuals.Preliminary observations on the life-history indicate that reproduction reaches its height in the summer and that fertilization probably takes place during the late summer and fall.
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    Journal of Morphology 45 (1928), S. 579-597 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: When Menidia eggs are fertilized with Prionotus sperm, the Prionotus chromosomes react in the Menidia cytoplasmic medium just as they do in the cytoplasm of Fundulus eggs. There is lagging, non-disjunction, and elimination of chromosomes during the early cell divisions. The mitotic behavior of the Prionotus sperm in the Menidia egg also resembles the behavior of the sperm of Ctenolabrus in the same medium. This behavior which was expected from what was known concerning the mitotic behavior of the reciprocal crosses between Menidia and Fundulus and between Ctenolabrus and Prionotus and other intercrosses between the members of these two groups is regarded as a function of the physical state of the egg cytoplasm during the division phase of mitosis. This physical character forms the earliest differential factor in the development of these hybrids and shows no correlation with the width of the cross.A comparison of nine teleost crosses, in which both the development and the early mitotic behavior are known, with a rough numerical estimate of the width of the cross brought out the fact that development is most successful in crosses between nearly related species if mitosis is normal and in distantly related crosses if mitosis is abnormal. This indicates that nuclear relationship is also a factor in the development of hybrids.
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    Notes: Virulent hay-infusion cultures of Bacillus pyocyaneus are toxic to pure-line races of three species of paramecia, but these races may acquire a tolerance for this toxic agent. Races with acquired tolerance have been grown for long periods of time in toxic, pure cultures of B. pyocyaneus by means of the daily-isolation culture method, and here the average division rate is as high as, or higher than, in the chance-mixed bacterial cultures in which these protozoa are usually maintained in the laboratory. The tolerance is lost, however, when the paramecia are removed from the toxic cultures and grown for a number of generations in cultures of non-toxic bacteria.The toxic agent that is lethal to paramecía is probably the soluble toxin of B. pyocyaneus. The investigation shows that the agent is soluble and either thermolabile or volatile. It also shows that all deleterious substances, other than the soluble toxin, known to be produced in cultures of this bacillus, are non-lethal to paramecia.Hay-infusion cultures of Bacillus enteritidis were lethal to paramecia. All attempts to develop tolerance in paramecia for the toxic agent in these cultures failed.Under the experimental conditions that prevailed, diphtheria toxin was found to have no appreciable effect upon the division rate or death rate in three species of paramecia.
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    Notes: Females of the marbled salamander, Ambystoma opacum, store sperm in exocrine glands called spermathecae in the roof of the cloaca. Eggs are fertilized by sperm released from the spermathecae during oviposition. Some sperm remain in the spermathecae following oviposition, but these sperm degenerate within a month and none persists more than 6 mo after oviposition. Thus, sperm storage between successive breeding seasons does not occur. Apical secretory vaculoes are abundant during the fall mating season and contain a substance that is alcian blue+ at pH 2.5. Production of secretory vacuoles decreases markedly after oviposition, and the glands are inactive by the summer months. Ambystoma opacum is a terrestrial breeder, and some mating occurs prior to arrival at pond basins where oviposition occurs. Mating prior to arrival at the ovipository site may prolong the breeding season, leading to fitness implications for both males and females. Females have opportunities for more matings, and the possibilities for sperm competition in the spermathecae are enhanced. © 1995 Wiley-Liss, Inc.
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    Notes: Alcichthys alciocornis has a viscous ovarian fluid in the ovarian cavity, which plays an important role in its unique mode of reproduction called internal gametic association (i.e., internal insemination and sperm-egg association but a delay in the physiological fertilization until spawning). Seasonal changes in fine structure of the inner epithelial lining and capillary endothelium of the ovary revealed that ovarian fluid originated as a result of the secretory activity of the tissues. The ovarian cavity of A. alcicornis is lined with an ovigerous lamella epithelium and an ovarian wall epithelium. During the spawning period, both epithelia actively secreted proteinaceous substances which seemed to constitute the ovarian fluid. The substances appear to be synthesized in the rough-surfaced endoplasmic reticulum from the material which was transported from the blood capillary, taken into the epithelial cells by endocytosis, accumulated in secretory vesicles via Golgi apparatus in the cells, and finally released into the ovarian cavity by exocytosis. Microapocrine secretion was also observed to occur in both epithelia. Secretory activity of both epithelia by exocytosis and microapocrine secretion showed distinct seasonal changes. Active exocytosis and microapocrine secretion were observed during the spawning period (April-May). These activities slightly declined during the degeneration period (May-June) and were lost during the early recovery period (July). During the mid to late recovery period (October-March), there was some exocytosis but no microapocrine secretion. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 167-174 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cell surface morphology of hamster decidual cells isolated from day 8 implantation swellings was studied, using both phase-contrast and scanning electron microscopy. Two kinds of cells, fibroblastic and epithelioid, were identified in cultures examined by phase-contrast microscopy. Fibroblastic cells were spindle-shaped, having pointed or blunt terminals on one end and bifid or webbed projections at the other end. Epithelioid cells, on the other hand, were flat and discoid, having a distinctively ruffled plasma membrane. Further, the plasma membrane of epithelioid cells formed rope-like or flange-like processes. The significance of such adaptations is discussed. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 149-166 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study investigates the effect of developmental stage on thyroid hormone (TH)-mediated remodeling in the skeletal tissues of hemidactyliine plethodontid urodeles. Rate of morphogenesis was quantified in 17 metamorphic tissues for three different size-age classes of Eurycea bislineata larvae immersed in a metamorphic dosage of T4. Extent of morphogenesis after a 3-week immersion was also quantified in these tissues plus four larval ones for the full size range of E. bislineata larvae and for less complete size ranges of E. wilderae, E. longicauda guttolineata, Gyrinophilus porphyriticus, and Pseudotriton ruber larvae. Although all tissues respond more slowly with decreasing size/age, two tissue-specific effects are evident in all species. Larval ossifications are less inducible than metamorphic ossifications, and progressive metamorphic events are more retarded and, in some cases, more prone to abnormal morphogenesis than regressive ones. The first effect agrees with the prediction that tissues that naturally remodel at metamorphosis are more responsive to a metamorphic dosage of TH than those that respond at a larval stage and lower TH. The second effect agrees with the prediction that progressive morphogenesis is more likely to be impaired at small size than regressive morphogenesis, although the frequent discrepancies between individuals of similar size implicate developmental age more than size in this effect. Collectively, these two effects provide only equivocal support for the hypothesis that direct development in plethodontids evolved via precocious TH activity. However, the unexpected transition from ceratobranchial replacement to ceratobranchial shortening in medium-sized larvae suggests that the former pathway requires a longer period of cell specification at low TH. Since ancestral plethodontids appear to have been distinguished by an exceptionally long larval period with exceptionally low TH activity, this developmental prerequisite may in turn be partly responsible for their singular evolution of ceratobranchial replacement. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 203-214 
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    Notes: The sagittal otolith of Hyperoglyphe antarctica (Centrolophidae: Teleostei) has a prismatic structure in which the anti-sulcal growth axes of each prism consist of a series of nested cones each composed of a mineral layer followed by an organic matrix layer. Broken sections show the mineral layers to be composed of stacks of crystals. Otolith matrix that has been decalcified and air-dried, or critical-pont-dried, retains a periodic structure of repeating high and low matrix density. At high magnifications, both broken whole crystal surfaces and decalcified matrix surfaces have a granular structure. Chloroxbleached whole otoliths also show a granular crystalline structure. At higher magnifications, the air-dried matrix showed a parallel fiber structure with similar dimensions to keratin fibers. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 191-201 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Ultrastructural descriptions of the dipnoan heart are lacking. Many ultrastructural features of the heart of the Australian lungfish, Neoceratodus forsteri, resemble those of other lower vertebrates. The epicardial cells appear to be adapated for the exchange of material with the pericardial fluid. The most prominent features of the endocardial cells are numerous moderately electron-dense vesicles found within the cytoplasm. These organelles might have an endocrine function. The myocardiocytes are typically small. The banding pattern of the sarcomere is shared with most fish. The intercalated disc has a convoluted path and consists of desmosomes and fascia adherens. Caveolae are a prominent feature of the sarcoplasm. The sarcoplasmic reticulum is sparse, and T-tubules are lacking. Atrial myocardial dense bodies occur in vast numbers throughout the atrium and are occasionally seen in the ventricle. These vesicles are chromaffin-positive but fail to show catecholamine fluorescence. They are likely to contain peptides related to ANP. Subendothelial cells exhibiting catecholamine-specific fluorescence are scattered throughout the atrium. Ultrastructurally these cells contain many chromaffin-positive granules. Chromaffin cells represent another cell type with a probable endocrine function within the heart of N. forsteri. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995) 
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    Journal of Morphology 223 (1995), S. 263-268 
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    Topics: Biology , Medicine
    Notes: A complex of lymphoepithelial organs, the “anal tonsils,” is a consistent structure in the anal canal of the bottlenose dolphin, Tursiops truncatus. This complex occurs as a circumferential cluster of discrete tonsil like aggregations of lymphoid tissues, together with epithelial ducts (“crypts”) and occasional mucus secretory units in the extreme lower portion of the intestinal tract. These structures are concentrated in the segment lined by stratified squamous epithelium and extend for a variable distance cephalad from the anal aperture. The tonsils appear to be most active, judged by the amount of lymphoid tissue present, in young animals. Depletion of lymphocytes and cystic enlargement of the crypts, probably representing functional as well as morphological involution, is a consistent feature of older animals. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 269-287 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The prenatal development of epidermis, dermis, and hypodermis was studied in embryos of different ago of two delphinid species (Stenella attenuata, Delphinus delphis), using light and transmission electron microscopical methods. The delphinid embryo is covered by a multilayered tissue formed by four different epidermal generations (periderm, stratum intermedium-I, str. intermedium-II, str. spinosum) produced by the str. basale. The first layer appears at about 40-50 mm of body length, the second type (s.i.-I) about 60-160 mm, and the third type (s.i.-II) is present at 160-500 mm. The first spinosal cells are produced at 225-260 mm body length; thenceforth, the epidermis increases continuously in thickness. Epidermal ridge formation begins about 400-mm body length. The development of the dermis is characterized by the early production of thin connective tissue fibers (40- 70-mm body length) and simultaneously the cutaneuous muscle matures in structure. Vascular development intensifies between embryos of 150-225 mm, and collagen production increases markedly in fetuses of 225-260-mm length. These events are paralledled by an increase in dermal thickness. The first elastic fibers can be recognized in the skin from the abdomen at about 600-mm body length. The development of the hypodermis is marked by very rapid and constantly progressing growth, beginning about 60-mm body length. The first typical fat cells appear in animals of 360-400 mm. Regional differences are obvious for all skin layers with regard to the flippers, where structural maturation proceeds more rapidly than in dorsal or abdominal regions. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 289-302 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Functional comparative morphology of predatory legs in five species of water bugs (Ilyocoris cimicoides, Nepa cinerea, Ranatra linearis, Notonecta glauca, and Gerris lacustris) has been investigatd adn the following peculiarities of leg design were revealed.1Subcoxal articulation may be monoaxial (G. lacustris, N. glauca), or, in contrast to walking leg type, biaxial (N. cinerea, R. linearis, I. cimicoides); the first axis is oriented along the coxa (torsion axis), the second one is perpendicular to the first (non-torsion axis).2In contrast to walking leg type, which is characterized by cross suspension of the axis of coxal rotation in thoracal skeleton, this axis in G. lacustris is placed vertically. Non-torsion coxal axis in R. linearis is oriented strongly transversal. This axis directs the leg strike forward.3Legs in the majority of species are planar: Torsion axes of the coxa, femur, and tibia are placed in the same plane. Axes of rotation of consequent joints in I. cimicoides are reciprocally sloped. Therefore, the end of the leg outlines the spiral trajectory, when all angles of joints are opening (closing). This is an adaptation for clinging to the stems of water plants.4Passive adduction of the femur in the trochanter-femoral joint in N. glauca allows it to go around protuberances of the body wall, when the leg is sliding along them; recurrent femur movement during releasing from the obstacele is active due to the rt.fe muscle.5Only R. linearis has predatory legs, which permit the high-speed pursuit of potential prey; other species realize this function using the swimming legs, whereas the forelegs are used for the manipulation movements.6Muscle arrangement in the prothorax of different species reflects both leg construction and constructional constraints of body design. Powerful flexor muscles (co1, co2, co3, co5, fl.ti, et.ti in R. linearis; fl.ta, fl.ti in N. glauca; fl.ti in I. cimicoides) have long tendons and short muscle bundles, which originate on the leg wall. As a result, the powerful force is developed along the muscle tendon.7Some features of the predatory leg are common for the species studies: elongation of coxae, thickening of femora, and increase of the degree of junction of tibia and tarsus. The muscles, which move the distal segment of the leg, are reinforced and the sclerite of the fl.ti tendon is enlarged. The joint angle of the distal segment is increased to 120°. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 223 (1995), S. 341-355 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Piranhas, like many teleosts, change their diets on both ontogenetic and phylogenetic time scales. Prior studies have suggested that pervasive morphological changes in body form on a phylogenetic time scale may be related to changes in diet, but previous reports have found little shape change in piranhas on an ontogenetic time scale. We re-examine the post-transformational allometry of body form in one piranha, Pygocentrus nattereri (Kner), using the method of thin-plate splines decomposed by their partial warps. We find substantial evidence of allometry, primarily elongation of the mid-body relative to the more anterior and posterior regions, elongation of the postorbital and nape regions relative to the more anterior head and posterior body, and deepening of the head relative to the body. In addition to these pervasive changes throughout the body, there are some that are more localized, especially elongation of the postorbital region relative to eye diameter and snout, and an even more localized elongation of the snout relative to eye diameter. Initial dietary transitions are associated with changes in head and jaw proportions, but rates of shape change decelerate through growth, so that the final transition to a diet increasingly dominated by small whole fish appears associated with change largely in overall body size. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 224 (1995), S. 87-96 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Muscles in the body wall, intestinal wall, and contractile hemolymphatic vessels (pseudohearts) of an oligochaete anelid (Eisenia foetida) were studied by electron microscopy. The muscle cells in all locations, except for the outer layer of the pseudohearts, are variants of obliquely striated muscle cells. Cells comprising the circular layer of the body wall possess single, peripherally located myofibrils that occupy most of the cytoplasm and surround other cytoplasmic organelles. The nuclei of the cells lie peripherally to the myofibrils. The sarcomeres consist of thin and thick myofilaments that are arranged in parallel arrays. In one plane of view, the filaments appear to be oriented obliquely to Z bands. Thin myofilaments measure 5-6 nm in diameter. Thick myofilaments are fusiform in shape and their width decreases from their centers (40-45 nm) to their tips (23-25 nm). The thin/thick filament ratio in the A bands is 10. The Z bands consist of Z bars alternating with tubules of the sarcoplasmic reticulum. Subsarcolemmal electron-dense plaques are found frequently. The cells forming the longitudinal layer of the body wall musculature are smaller than the cells in the circular layer and their thick filaments are smaller (31-33 nm centrally and 21-23 nm at the tips). Subsarcolemmal plaques are less numerous. The cells forming the heart wall inner layer, the large hemolymphatic vessels, and the intestinal wall are characterized by their large thick myofilaments (50-52 nm centrally and 27-28 nm at the tips) and abundance of mitochondria. The cells forming the outer muscular layer of the pseudohearts are smooth muscle cells. These cells are richer in thick filaments than vertebrate smooth muscle cells. They differ from obliquely striated muscle cells by possessing irregularly distributed electron-dense bodies for filament anchorage rather than sarcomeres and Z bands and by displaying tubules of smooth endoplasmic reticulum among the bundles of myofilaments. © 1995 Wiley-Liss, Inc.
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  • 75
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    Notes: In this report, the gonads of 32 glandulocaudine species, representing 18 genera, are compared with 11 outgroup characiform species. Through the presence of spermatozoa within the ovarian cavity, internal fertilization of the female is confirmed for the 16 genera for which mature ovaries were available. No outgroup ovary studied contains spermatozoa. All mature glandulocaudine testes have a large portion of the posterior testis, which is devoid of developing germ cells and spermatocysts (aspermatogenic), devoted to sperm storage, with the degree of partitioning in that region varying greatly within the group. All outgroup species examined have spermatozoa with spherical nuclei. With the exception of the species of the genus Planaltina, which also have spherical nuclei, all glandulocaudines have elongated nuclei, which vary among the species from 3.6 μm to 31.6 μm in length. Distinct sperm packets (spermatozeugmata) are formed in five genera by two different methods. In the genera Xenurobrycon, Tyttocharax, and Scopaeocharax, all of the tribe Xenurobryconini, the spermatozeugmata are formed within the spermatocysts and released fully formed. In all genera of the tribe Glandulocaudini, which includes Glandulocauda and Mimagoniates, loose spermatozoa are released which cluster into spermatozeugmata within the posterior storage areas. These morphological specializations are discussed within a phylogenetic framework as adaptations for internal fertilization and are hypothesized to be independently derived. © 1995 Wiley-Liss, Inc.
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  • 76
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    Journal of Morphology 224 (1995), S. 199-203 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Interdigitating cells in the thymus of the sea bass, Dicentrarchus labrax, occur principally in the internal zone and in the border with the external zone. Ultrastructurally, the most characteristic cytological features of these cells are their low electron density, complicated labyrinthine membrane-membrane contacts, scantiness of cytoplasmic organelles, presence of Birbeck-like granules, juxtanuclear tubulo-vesicular complex, and phagocytic capacity. © 1995 Wiley-Liss, Inc.
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  • 77
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    Notes: Morphological and ultrastructural features of the salivary glands and proboscises of Placobdella ornata, Placobdella parasitica, and Desserobdella picta were studied by light and electron microscopy. Chemical composition of the salivary cells was investigated using a variety of histochemical techniques. Placobdella ornata and P. parasitica have compact salivary glands with discrete pairs of anterior and posterior glands, while the salivary cells contain one mucous and three proteinaceous secretions. Salivary glands of D. Picta are diffusely arranged and contain two mucous and two proteinaceous secretions. A cobalt-lysine forward-filling technique revealed that individual salivary cells consist of a roughly spherical soma and an elongated ductule. The majority of the internal space in a salivary soma is densely packed with spherical secretory granules which displace the cytoplasm to the periphery of the cell. Bundles of individual ductules enter the base of the proboscis on opposite sides and extend anteriorly. The ductules, also packed with secretory granules, are surrounded by microtubules associated with agranular endoplasmic reticulum, and merge with deep invaginations of the proboscis cuticle. The secretory granules are released at the end of these invaginations or pores. Pores were found on the tip, along the body, and on the luminal wall of the proboscises in all three species. © 1995 Wiley-Liss, Inc.
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  • 78
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    Journal of Morphology 225 (1995), S. 61-75 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Longitudinal and principal strain recordings were made in vivo at three sites (dorsal, anterior, and ventral) on the humeral midshaft of pigeons executing five modes of free flight: Take-off, level flight, landing, vertical ascent, and near-vertical descent. Strains were also recorded while the birds flew carrying weights that were 33%, 50%, or 100% of their body weight. The relative distribution of strain measured at the three surface midshaft sites and across the bone's cortex was found to be similar for all flight modes. Principal strains recorded in the dorsal and ventral humerus indicated considerable torsion produced by aerodynamic loading of the wing surface posterior to the bone. Measured torsional shear strains (maximum: 2,700-4,150 μ ε during level flight) were 1.5 times greater than longitudinal strains. In addition to torsion, the humerus is also subjected to significant dorsoventral bending owing to lift forces acting on the wing during the downstroke. Analysis of the cross-sectional distribution of longitudinal strains at the humeral midshaft cortex shows that the orientation of bending shifts in a regular manner during the downstroke, indicating that the wing generates progressively more thurst (vs. lift) later in the downstroke. This shift is less during take-off and vertical ascent when greater lift is required. Peak principal and longitudinal strains increased by an average of only 50% from landing to vertical ascending flight and take-off (e.g., dorsal humerus: -1,503 to -2,329 μ ε) and did not exceed -2,600 μ epsiv; at any site, even when the birds flew carrying twice their body weight. Strains recorded when birds flew at two times their body weight (100% BW load) were similar in magnitude to those recorded during vertical ascent and take-off and likely represent those developed during maximal performance. Strains developed within the midshaft were maximal in the anterodorsal and posteroventral cortices, not at the dorsal, ventral, and anterior sites at which strain was recorded. Consequently, maximum strains experienced by the bone are probably 20-25% greater than those recorded (ca. 3,200 μ ε), indicating a safety factor of about 3.5 for compressive strain failure. The much higher shear strains, however, indicate a lower safety factor (1.9), in which the bone's torsional strength is its most critical design feature. Finally, the magnitude and distribution of strains developed in the humerus of pigeons are generally similar to those recorded in the humerus of large fruit-eating bats during flight. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 107-123 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Cephalometry was used to detect patterns of cranial growth in fetal bats that were stained differentially for bone and cartilage. Three developmental features distinguish embryos of taxa that echolocate nasally from embryos of taxa that echolocate orally: (1) the basicranium is retained ventral to the cervical axis, (2) the rostrum is retained below the basicranial axis, and (3) the lateral semicircular canals are rotated caudally. Together, the first two actions align the fetal nasal cavity with what will be the long axis of the adult body in flight. The third action aligns the lateral semicircular canals with the horizontal. In contrast, skulls of oral-emitting taxa are constructed such that the oral cavity is aligned with the long axis of the body in flight. The evolution of head posture and skull form in microchiropteran bats has been constrained by the demands of vocalization, i.e., ultrasonic echolocation. Accordingly, the ontogeny of the microchiropteran skull has been canalized along two distinct developmental paths - oral-emitting and nasal-emitting Baupläne. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995) 
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  • 81
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    Journal of Morphology 225 (1995), S. 251-260 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Assulina muscorum secretes morphologically altered shells when cultured in a medium with 5 mM caffeine. The siliceous scales, normally distributed in a regular overlapping pattern, are disorganized, thicker and wider than normal, and occasionally have incompletely silicified surfaces that appear irregular in profile in transmission electron microscopic ultrathin sections. The shape of the silica deposition vesicles (SDVs) in the cytoplasm is altered and they are less regularly arranged. The swollen appearances of the SDVs, and of nearby Golgi tubules, give additional evidence that caffeine affects the fine structural morphology of membranous secretory organelles and can disrupt their normal depositional activity. In addition to the greater thickness and width of the siliceous scales in caffeine-treated cells, the length and width of the shell are larger compared to controls, but the aspect ratio (length / width) is smaller. The latter is attributed to a larger increase in width relative to the increase in length of the caffeine-reated cells. Since some of the scales are deposited with the long axis laterally on the shell surface, in addition to being greater in width, this raises the interesting question of whether the morphology of the SDVs and the siliceous products influences the size and morphogenesis of the shell. Further research is needed to clarify the interaction of the SDVs with the cytoplasmic cytoskeletal system during shell morphogenesis. © 1995 Wiley-Liss, Inc.
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  • 82
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: This study deals with some macroscopical, microscopical, and ultrastructural aspects of the spinal cord central canal of the German shepherd dog. The caudal end of the spinal cord is constituted by the conus medullaris, which may extend to the first sacral vertebra, the terminal ventricle, and the filum terminale. The latter structure is considered as internum (second to third sacral vertebrae) or externum (fifth caudal vertebra), according to its relation to the dura mater. Occasionally, there is a second anchorage which is close to the level of the sixth caudal vertebra. The central canal is surrounded by a ciliated ependymal epithelium, which differs depending upon the levels. The most caudal part of the filum terminale bears a columnar ciliated ependymal epithelium surrounded by two layers of glia and pia mater, which separate the central canal from the subarachnoid space. Microfil injections show a communication between the cavity and the subarachnoid space, as the plastic is able to pass through the ependymal epithelium. At the level of the terminal ventricle there are real separations of the ependymal epithelium, which seem to connect the lumen of the spinal canal with the subarachnoid space. These structures probably constitute one of the drainage pathways of the cerebrospinal fluid. The diameter of the central canal is related to the age of the animal. However, even in very old animals the spinal cord central canal reaches the tip of the filum terminale and remains patent until death. At the ultrastructural level the ependymal cells present villi, located on cytoplasmic projections, cilia, dense mitochondria, and oval nuclei. © 1995 Wiley-Liss, Inc.
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  • 83
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    Journal of Morphology 224 (1995), S. 179-198 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Female reproductive tracts of the viviparous neo-tropical onychophoran Peripatus acacioi have been examined at different times throughout the year, and the altering relationship between the developing embryo and the uterus is described. Depending on her age and time of year, the female may have one or two generations of embryos within her uterus. The uterine wall consists of a thin outer epithelium and basal lamina, three layers of muscles, and a thick basal lamina beneath an inner epithelium lining the uterus lumen. These layers are consistent along the length of the uterus apart from the inner epithelial lining, which varies according to position in the uterus and the developmental stage of embryos contained in the uterus. Early embryos are positioned along the length of the uterus and therefore have space in which to grow. During cleavage and segment formation, each embryo is contained within a fluid-filled embryo cavity that increases in size as the embryo grows. Morulae and blastulae are separated by lengths of empty uterus in which the epithelial lining appears vacuolated. Until the process of segment formation is complete, the embryos are attached to a placenta by a stalk and remain in the same part of the upper region of the uterus. As these embryos grow, the lengths of vacuolated cell-lined uterus between them decrease. Each embryo cavity is surrounded by the epithelial sac, the maternal uterine epithelium, which becomes overlaid by a thin layer of cells, the embryo sac, which is believed to be of embryonic origin. The placenta is a syncytial modification of the epithelial sac located at the ovarian end of each embryo cavity covered by the embryo sac and is analogous to the mammalian noninvasive epitheliochorial placenta. Segment-forming embryos have their heads directed toward the ovary. As the embryo gets longer during segment formation, its posture changes from coiled to flexed. Once segment formation is complete, the embryo loses contact with its stalk, an embryonic cuticle forms, and the embryo turns around so that its head is directed toward the vagina. The embryo escapes from its embryo sac and moves to the lower part of the uterus. In the lower part of the uterus, the straightened fetuses are first unpigmented but subsequently become pigmented as the secondary papillae on the body surface form and an adult-type cuticle forms beneath the embryonic cuticle. While the embryos are contained within their embryo cavities, nutrients are supplied by the placenta. Throughout development the mouth is open and in the mature fetus the gut is lined by peritrophic membrane and material is present in the gut lumen. Trachea have been observed only in fetuses that were ready for birth. Insemination, cyclical changes in the uterine epithelium, and the nature of the cuticle shed at parturition are discussed. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 91-105 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The supporting elements of the avian propatagium were examined in intact birds and as isolated components, using static force-length measurements, calculated models, and airflow observations. The propatagial surface supported between Lig. propatagiale (LP) and brachium-antebrachium is equally resistant to distortion over the range of wing extension used in flight. The lengths LP assumes in flight occur across a nearly linear, low-stiffness portion of the force-length curve of its extensible pars elastica. In an artificial airflow, intact wings automatically extend; their degree of extension is roughly correlated with the airflow velocity. Comparisons between geometric models of the wing and the passive force-length properties of LPs suggest that the stress along LP blances the drag forces acting to extend the elbow. The mechanical properties (stiffness) of the LP vary and appear to be tuned for flight-type characteristics, e.g., changes in wing extension during flight and drag. Lig. limitants cubiti and LP combine to limit elbow extension at its maximum, a safety device in flight preventing hyperextension of the elbow and reduction of the propatagium's cambered flight surface. Calculations using muscle and ligament lengths suggest that M. deltoideus, pars propatagialis, via its insertions onto both the propatagial ligaments, controls and coordinates propatagial deployment, leading edge tenseness, and elbow/wing extension across the range of wing extensions used in flight. The propatagial ligaments and M. deltoideus, pars propatagialis, along with skeleto-ligamentous elbow/carpus apparatus, are integral components of the wing's extension control mechanism. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 125-167 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A new approach to devising embryological staging systems allows improved phylogenetic comparisons of developmental patterns. As in traditional approaches, morphological features provide the defining criteria for stages, but unlike traditional normal tables, each stage is defined by no more than one or two morphological criteria that are fundamental developmental features of all teleosts. Additional developmental features that occur concurrently with the defining criteria of a stage are treated as variables potentially uncoupled from the defining criteria for that stage. This system is well suited to detect phylogenetic heterochrony and promises to increase our understanding of conserved vs. labile features in teleostean embryology. In this study, I explain the defining criteria for American shad and then make comparisons with other clupeoids. The development of American shad includes 35 stages extending from fertilization to metamorphosis. Comparisons with other clupeoids indicate that the developmental pattern of shad is representative of the early ontogeny of many clupeoids during the embryonic and yolk sac periods and may be conservative for the group. However, several concurrent features, particularly hatching, formation of neuromasts, and opercular development, vary in developmental timing among clupeoids. Comparisons indicate that shad embryos delay the development of these concurrent features relative to other clupeoids. Modifications of the developmental pattern for different species of clupeoids are heterochronic but their phylogenetic and adaptive significance is unknown. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 193-211 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A description is provided of the fiber-type composition of several hindlimb muscles of the adult turtle, Pseudemys (Trachemys) scripta elegans. In addition, cross-section areas of each fiber type and an estimation of the relative (weighted) cross-section area (wCSA) occupied by the different fiber types are also provided. Seven muscles were selected for study, based on their suitability for future neurophysiological analysis as components of the segmental motor system, and on their homologies with muscles in other vertebrates. The test muscles were iliofibularis (ILF), ambiens (AMB), external gastrocnemius (EG), extensor digitorum communis (EDC), flexor digitorum longus (FDL), tibialis anterior (TA), and peroneus anterior (PA). Serial sections of these muscles were stained for myosin adenosine triphosphatase (ATPase), NADH-diaphorase, and alpha-glycerophosphate dehydrogenase (α-GPDH), thereby enabling fiber-type classification on the basis of indirect markers for contraction speed and oxidative (aerobic) vs. glycolytic (anaerobic) metabolism. All muscles contained three fiber types: Slow oxidative (SO; possibly including some non-twitch tonic fibers); fast oxidative glycolytic (FOG); and fast glycolytic (Fg). There were at least 30% FOG and 50% FOG + Fg fibers in the seven muscles, the extreme distributions being the predominantly glycolytic ILF vs. the predominantly oxidative FDL muscle (ILF - 15.5% SO, 35.2% FOG, 49.3% Fg vs. FDL - 49.1% SO, 41.1% FOG, 9.8% Fg). As in other species, the test muscles exhibited varying degrees of regional concentration (compartmentalization) of the different fiber types. This feature was most striking in ILF. Pronounced compartmentalization was also observed in AMB, EG, PA, TA, and EDC, whereas the distribution of fiber types in the highly oxidative FDL was homogeneous. In five of the seven muscles, fiber size was ranked with Fg 〉 FOF 〉 SO. In terms of wCSA, which provides a coarse-grain measure of the different fiber types' potential contribution to whole muscle peak force, all muscles exhibited a higher Fg and lower SO contribution to cross-section area than suggested by their corresponding fiber-type composition. The largest relative increases in wCSA vs. fiber-type composition were in the ILF and AMB muscles. We conclude that the turtle hindlimb provides some interesting possibilities for testing for a division of labor among different muscles during different movements (e.g., sustained vs. ballistic), and for study of the behavior of the different fiber (and motor unit) types under normal and perturbed conditions. The relationships between the present results and previous findings on homologous muscles of the mammalian (cat, rat) and reptilian (lizard) hindlimb are discussed. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 261-268 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: During the breeding season, the terminal end of the ductus deferens of Calotes versicolor appears swollen and is comparable to the ampulla of the mammalian ductus deferens. Its anatomy was studied from paraffin sections. It differentiates along its length into five zones. The first has thick smooth muscle and pesudostratified epithelium; the second has luminal trabeculae with an epithelium showing evidence of secretory activity; the third has the epithelial mucosa abutting against the smooth muscle in the form of pocketlike indentations; the fourth has crypts between epithelial folds; and the fifth zone is a sphincter. The anatomy of this ampullary region is indicative of secretory as well as spermatophagous roles. It undergoes seasonal change and appears to be androgen-dependent. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 225 (1995), S. 357-367 
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    Notes: Endothermic heat production and the capacity to shiver develop soon after hatching in birds, permitting chicks to regulate their body temperature. Physiological studies have not clearly identified the developmental events causing this change in function. Here, we use electron microscopy to examine the development of structures involved in muscle activation, contraction, and metabolism coincident with the development of shivering thermogenesis. A stereological study was used to compare the ultrastructure of chicken iliofibularis before endothermic heat production was present (24 h before hatching) and 120 h later, when the iliofibularis had substantial capacity for shivering. Profound increases were found in the t-tubule system and terminal cisternae, mitochondrial cristae, and lipids. The number of triadic profiles increased 3.8-fold (7.6 ± 1.31/100 μm2 to 28.5 ± 2.90/100 μm2 fiber area). The surface area of cristae per mitochondrial volume doubled (12.0 ± 1.50 pm2/pm3 to 25.7 ± 1.84 μm2/μm3). Lipid droplets were rare in the iliofibularis of embryos about to hatch, but accounted for 4.4% of the muscle fiber volume in day 4 birds. We suggest that these ultrastructural changes more fully activate the iliofibularis, allow it to produce more heat both from calcium pumping and from contraction, and increase its endurance, thus permitting the muscle to be effective in thermogenesis. © 1995 Wiley-Liss, Inc.
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    Journal of Morphology 226 (1995) 
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  • 90
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    Journal of Morphology 226 (1995), S. 25-31 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: Five types of sensilla are situated on the apical area of the labial and maxillary palpi and galea of Cicidela sexguttata. Large, conical, and peg-like sensilla are in rows on the central region of each palpus. These sensilla have a hollow cuticular peg, with an apical pore and multi-innervation. This central region of palpal sensilla is surrounded by campaniform sensilla that are disc-shaped and small conical peg sensilla. A similar type of conical sensillum as the found in the palpal central region is situated around the periphery of the palpal apex and apex of the galea. This conical peg sensillum is located in a shallow depression and is structurally similar to the other peg sensilla, but it has a mechanoreceptor neuron attached to the cuticular base of the sensillum. A long, single, trichoid sensillum is situated in the center of the galea and is hollow, thick-walled, porous, and multi-innervated. The apices of the palpi and galea have a large number of dermal gland openings that actively secrete a substance during the feeding process of the tiger beetle. © 1995 Wiley-Liss, Inc.
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  • 91
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    Notes: Changes in ovarian histology during the reproductive cycle of the viviparous lizard Sceloporus torquatus torquatus are described. In general, the variation in follicular histology observed during the seasonal cycle is similar to that of other lizards. Sceloporus t. torquatus exhibits a cycle in which small, previtellogenic follicles exist in the ovary from December to August. Vitellogenesis occurs between September and November, followed by ovulation from late November to early December. Parturition occurs the following spring. After ovulation, the remaining follicular cells form the corpus luteum and luteolysis did not occur until April-May. Follicular atresia is commonly observed in previtellogenic follicles with polymorphic granulosa, but occurs less frequently in follicles during late vitellogenesis. There are two germinal beds in each ovary. The yolk nucleus is evident in young oocytes as is a vacuolated ooplasma prior to vitellogenesis. Extensive polymorphism is observed in yolk platelets. Mast cells and secretory cells are observed in the thecal layer of the follicular wall as are melanocytes in the ovarian stroma. © 1995 Wiley-Liss, Inc.
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  • 92
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    Journal of Morphology 226 (1995), S. 159-171 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ectoplacental cones isolated from embryos on the seventh day of pregnancy wer transplanted beneath the hepatic capsule of recipeint adult animals to document the morphological patterns of vascular invasion by the trophoblast in the absence of the maternal environment and the influence of its peculiar vasculature. Females, and females and males of Calomys collosus, a cricetid rodent, were used, respectively, as embryo donors and recipient animals. Three to 5 days later, the grafted regions were excised and processed for light and electron microscopy. Invasion of the liver parenchyma by the trophoblast progressed along the vascular beds, associated with gradual phagocytosis of hepatic cells, greatly favoring the morphological characterization of invasive steps exhibited by the trophoblast to access the different kinds of vessels, to trespass the various vascular components and the different levels of the surrounding hepatic parenchyma. It is possible that either in utero during the establishment of embryomaternal circulation in early pregnancy or ex utero under experimental conditions, the trophblast exhibits similar vascular invasion behavior. In view of this, our findings may contribute to a better understanding of trophoblast cell migration to the maternal blood supply as well as the role of the trophoblast in the establishment of the placental circulation during pregnancy. © 1995 Wiley-Liss, Inc.
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    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A commentary is provided on the segmental motor system of the turtle Pseudemys (Trachemys) scripta elegans with an emphasis on neuronal, neuromuscular, and muscular mechanisms that control the development of force under normal, fatiguing, and pathophysiological conditions. For the central neuronal component of the segmental motor system, it has recently been shown that intracellular analysis of the firing properties of motoneurons and interneurons can be undertaken for relatively long periods of time in in vitro slices of the lumbosacral spinal cord of the adult turtle. In other less reduced in vitro preparations, analyses are available on complex motor behaviors generated by the isolated spinal cord. These behaviors of spinal neuronal networks are analogous in key aspects to those generated by the isolated in vivo cord, and by the cord in intact preparations. These results suggest that the neuronal components of the segmental motor system can now be studied from the cellular/molecular level of analysis in in vitro slice preparations to the systems level in conscious, freely moving animals. The in vitro approach can also be used for the analysis of cellular mechanisms in suprasegmental brain structures, which contribute to the control of voluntary movement. For the peripheral neuromuscular component of the segmental motor system, information is now available on muscle fiber types and selected aspects of sensory innervation, and it is feasible to study the mechanical and biochemical properties of motor units. As such, the turtle presents a valuable model for exploring interrelations between the neuronal and mechanical components of the segmental motor system of the generalized tetrapod. A prominent feature of these recent developments is the extent to which they have been deriven by findings that have emphasized an evolutionary conservation of motor-control mechanisms extending from ion channels, at the cellular level, to the control of multijointed movements at the systems level of analysis. © 1995 Wiley-Liss, Inc.
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  • 94
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    Journal of Morphology 40 (1925), S. 261-297 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The parasynaptic union of chromosomes associated with the formation of a karyosphere is demonstrated in the spermatocytes of Phanaeus.The twelve V-shaped leptotene threads are polarized with their apices embedded in one plasmosome-like body, their distal ends in another (primary and secondary caps, respectively), and undergo a conjugation of the parasynaptic type. The distal ends of the chromosomes are freed from their attachment in the secondary cap. The six pachytene loops retain their polarized configuration.The basichromatin of the pachytene chromosomes appears ultimately to be withdrawn to form the karyosphere comprising six chromatic bodies within an oxychromatic «plasmosome,» the latter probably derived from the primary cap. The two caps are believed to arise from the chromosomes. The primary cap apparently becomes incorporated again in the chromosomes; the secondary cap, together with linin remnants of the pachytene chromosomes, disintegrates in the nucleus as residual chromatin.In the dissolution of the karyosphere six ring-shaped tetrads emerge arranged in a temporarily connected chain, giving under certain conditions, the misleading impression of twelve components arranged end to end. The entire content of the karyosphere appears to be employed in the formation of the chromosomes; no visible plasmosome remains.
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  • 95
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    Journal of Morphology 41 (1926), S. 441-546 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryological study of bullfrog tadpoles collected from various parts of the United States has shown the existence of local races which differ markedly in regard to the time of occurrence and character of the developmental processes involved in the formation of the definitive testis of the male individuals. Those races in which the gonads of the two sexes are easily distinguished in early larval stages are called differentiated. Other local races show a peculiar gonadic development chiefly affecting the males, the definitive testis sometimes not appearing until near the end of the second year of larval life. Such races are called undifferentiated, because the morphological features of the definitive testes are not established until late. The larvae first develop a peculiar gonad (progonad) which later degenerates and is replaced by the definitive testis. All male animals of the undifferentiated strains exhibit the gonad cycle.The progonad varies among the local frog races in regard to the length of persistence and degree of differentiation attained before undergoing degeneration. Its germ cells may exhibit a typical male maturation cycle ending in degeneration, or the cells may differentiate along both male and female lines or remain sexually neutral.The development and differentiation of the progonad in the various races are described and a detailed account given of the origin of the definitive testis. The problems of sex differentiation and continuity of the Keimbahn in anurans are discussed.
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  • 96
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The primordial germ cells of urodeles and anurans can occupy comparable positions in the embryo only in very early stages of development, if at all. When first recognizable as reproductive elements, their situation in the two amphibian orders is quite strikingly different.The germ cells first become recognizable in urodeles in the medial edge of the lateral mesoderm; there is no evidence that their position previous to this time is other than mesodermal. In the anura they are entodermal in association during early development; they are finally separated from the dorsal portion of the roof of the archenteron to form a single axial germ-cell cord. No amphibian species studied showed a mode of origin different from that characteristic of its order.The so-called migration of the amphibian germ cells to their definitive situation is interpreted as the result of growth shiftings of related parts. Germ cells do not migrate independently through the tissues. Aberrant or ectopic cells for the most part result from failures or faulty correlations of growth processes. Certain aberrant cells of the caudal portion of the body in urodeles indicate the inclusion of sex elements in the ventral as well as in the lateral mesoderm.
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  • 97
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The musculature of the ophidian head is a fairly complex structure, due to the specialization of the skull and the peculiar movements and motions made possible by the high degree of streptostylism.This musculature has been derived from the lacertilian type by a splitting and a shifting of the original elemental muscle masses of this group. Most of the muscles are clearly homologous with those of the Lacertilia. Some cannot be homologized by a study of the mature forms.The greatest differences lie in the separation of the muscle masses in the ophidia, as compared with the undivided masses in the Lacertilia. Since the jaw movements of the Lacertilia are rather simple, there is no need for any subdivision or splitting of the jaw muscles, but with the complex movements of the ophidia this becomes necessary.A few of the ophidian muscles appear to be neomorphs, as no key to their origin could be determined by a comparison with lacertilians.
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  • 98
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    Journal of Morphology 41 (1926) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 99
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    Journal of Morphology 41 (1926), S. 333-345 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a leech infesting the Alaskan codfish germinal masses in the ovary proliferate secondary groups, comprising about forty cells in which a follicle and central supporting cell early differentiate. Active division results in approximately 500 cells which apparently develop ductules extending to a point on the surface of the egg. Granules of unknown origin then appear in each nurse cell, and are drawn down the ductules into the egg which can now be distinguished. Reasons are given for the belief that the nutritive material is drained from the nurse cells by amoeboid activity of the egg. In early stages the nutritive mateiral forms a loose reticulum which gradually becomes transformed into a more extensive network, persisting until the maturation divisions. In this latest period the follicle and nurse cells, which become shrunken as the ovum enlarges, usually are stripped off and soon disintegrate.
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  • 100
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    Journal of Morphology 41 (1926), S. 547-579 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pelvic fins of the ancestors of the Chondrosteoidei possessed a metameric musculature and their skeleton consisted of a large number of metamerically arranged cartilaginous fin-rays, to which were attached osseous lepidotrichia. Evolution has involved the concrescence of separate elements to form the basal cartilage, the proximal end of which forms the girdle of the fin; the loss of a number of the fin-rays, and the atrophy of distal elements of the rays. The adult Chondrosteoidei have retained the primitive fin structure which characterized the elasmobranchs of the Palaeozoic period and which has disappeared in recent forms.
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