Online ISSN : 1348-7019
Print ISSN : 0011-4545
Volume 2, Issue 3
Displaying 1-4 of 4 articles from this issue
    1931 Volume 2 Issue 3 Pages 175-233
    Published: June 15, 1931
    Released on J-STAGE: March 19, 2009
    An argument is presented in support of the hypothesis that segmental interchange or the mutual exchange of parts of non-homologous chromosomes, is responsible for the formation of circles of chromosomes found during meiosis in Oenothera. The chief points which are made are:
    1. There is no chromosome configuration possible to 14-chromosome Oenotheras which can not be formed in an enormous number of ways by the proper arrangement of the ends of two sets or complexes of 7 chromosomes, and the Union of these complexes in pairs.
    2. Even the most complicated chromosome configurations, and those involving the largest circles, could have arisen in nature by very short series of simple segmental interchanges, and it is quite easy to conceive of the origin of large circles in the course of evolution as due to such interchanges.
    3. It is possible an the basis of this hypothesis, using as data the facts already known regarding chromosome arrangements and linkage relations in the various species and hybrids, to predict what the chromosome arrangement must be in certain hybrid combinations. In all, it has been possible so far to make 8 predictions. Three of these have not as yet been tested, but in the other 5 Gases the predictions have agreed with the facts. It has further been shown that the pure-ly mathematical odds against success in prediction in the degree which has attended this effort are more than 375, 000 to one. The fact that, in a number of hybrids at least, the only chromosome configuration possible an the basis of segmental interchange is the configuration actually found; as well as the fast that no Gases have been found in which the configuration present is theoretically impossible an the basis of segmental interchange, suggests most strongly that segmental interchange is at the basis of circle formation. Detailed reasoning is presented in the rase of each predietion.
    Finally, certain seeming difficulties in the way of the hypothesis are discussed, and are found to be in all probability more apparent than real. All indications at present point toward the probability that segmental interchange is responsible for the end to end Union of chromosomes in meiosis in Oenothera.
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  • III. Zur Entstehungsweise eines neuen konstanten oktoploiden Aegilotricum
    1931 Volume 2 Issue 3 Pages 234-255
    Published: June 15, 1931
    Released on J-STAGE: March 19, 2009
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    1931 Volume 2 Issue 3 Pages 256-282
    Published: June 15, 1931
    Released on J-STAGE: March 19, 2009
    1. The object of this study was to discover whether the chromo-some behaviour in Rosa was in agreement with the chiasma theory of chromosome pairing.
    2. Somatic chromosomes in Rosa showed primary and secondary constrictions and varied in length from about 1.5μ to 3μ. Pairing at diakinesis was found to be by chiasmata.
    3. Chiasma-frequency was analysed in pollen mother cells of two diploid roses, a) the polyantha pompom garden rose “Orleans, ” and b) a wild plant of Rosa blanda. The mean number of chiasmata was of the same order in both individuals, namely 1.72 and 1.75 per bivalent at diakinesis, and 1.53 and 1.31 per bivalent at metaphase. The effect of terminalization was apparent in the regular falling off of the mean number of chiasmata per potential bivalent, and in the reduction in the Proportion of interstitial to terminal chiasmata from early diakinesis to metaphase. A small proportion of chromosomes failed to form chiasmata and therefore appeared as univalent chromo-somes.
    4. Quadrivalent configurations were found at diakinesis and at metaphase in both the diploid roses : a phenomenon correlated with structural hybridity of the chromosomes. The fact that a similar Pro-portion of the chromosomes were present as univalents, and involved in quadrivalents, at metaphase as at diakinesis, is offered as a proof that end to end associations are terminal chiasmata.
    5. Rosa blanda, showed a few sexivalents as well as bivalent, trivalent and quadrivalent configurations at diakinesis. The structure of the chromosomes in some of the quadrivalents has been inter-preted an the basis of segmental interehange in conjunction with parasynapsis. The plant is shown to be 3n for one short segment.
    6. The diploid individuals both showed approximately 50% of bad pollen.
    7. The highly sterile tetraploid Rosa relicta was found to have a mean chiasma-frequency of 1.71 per potential bivalent at diakinesis. Quadrivalents were frequent and the presence of multivalents involving 5, 6, and 8 chromosomes showed that the plant was also a structural hybrid.
    8. Pairing in Rosa is by chiasmata as in other organisms. Failure of pairing as well as multivalent pairing involving segmental interchange affeet part of the chromosome complement and not the rest. HURST's theory of seven differential septets of chromosomes in Rosa is thus proved untenable by direct cytological observation.
    9. The phenomenon of “secondary pairing” is exhibited by some polyploid roses.
    10. An alternative hypothesis is given to account for the un-balanced polyploid species of the Caninae, which does not involve a hypothetical decaploid ancestral form.
    I wish to acknowledge my indebtedness to the Director of the John Innes Horticultural Institution for the use of laboratory facilities. I am also grateful to Dr. C. D. DARLINGTON for helpful suggestions and advice.
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    1931 Volume 2 Issue 3 Pages 283-289_1
    Published: June 15, 1931
    Released on J-STAGE: March 19, 2009
    Das bisher allgemein zur Isolierung von Kutikulen rezenter Pflan-zenmaterialien benutzte SCHULZE'sche Gemisch wurde für diesen Zweck als sehr brauchbar gefunden; nur bei sehr zarten Objekten können sich bei seiner Verwendung Schwierigkeiten ergeben. An Stelle der bisher benutzten Lösung wird eine heiß gesättigte Lösung von Kalium-chlorat in Salpetersäure nach VODRÁZKA empfohlen.
    Bei den meisten Objekten läßt sich die Kutikula in befriedigender Weise auch dadurch isolieren, daß die Gewebe zuerst mit 30-50% Schwefelsäure im Thermostaten bei einer Temperatur von 70°C. durch 24 Stunden behandelt und dann nach Auswaschen in Wasser durch längere Zeit (1-2 Tage) der Einwirkung von schwach alkalischem 5-10% Wasserstoffsuperoxyd im Thermostaten ausgesetzt werden.
    Eine überaus sichere und schonende Isolierung der Kutikulen, selbst zartester, ist mit Hilfe des Eau de Javelles möglich. Das Material muß etwa 1 Woche in einem gut verschließbaren Gläschen in frischem Eau de Javelle verweilen, das zweckmäßßig jeden zweiten Tag gewechselt wird. Nach beendeter Einwirkung gelangen die Objekte in 5% Salz-säure, durch die das anhaftende Kalziumkarbonat und ev. noch vor-handene Zellreste vollständig aufgelöst werden. Es bleiben nur die reinen Kutikulen zurück.
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