Catalogue of scientific papers, 1800-1863 [to 1884-1900]. Compiled by the Royal Society of London.

v. 2

Catalogue of scientific papers, 1800-1863 [to 1884-1900]. Compiled by the Royal Society of London.

v. 16

Catalogue of scientific papers, 1800-1863 [to 1884-1900]. Compiled by the Royal Society of London.

v. 17

Catalogue of scientific papers, 1800-1863 [to 1884-1900]. Compiled by the Royal Society of London.

v. 1

Die Borstenwürmer (Annelida Chaetopoda) nach systematischen und anatomischen Untersuchungen dargestellt / von Ernst Ehlers.

Abt. 1 & 2

Text-book of palaeontology /

v. 2 (1902)

The life and letters of Charles Darwin, including an autobiographical chapter. Edited by his son, Francis Darwin.

3

The life and letters of Charles Darwin, including an autobiographical chapter, ed. by his son Francis Darwin ...

1

A ação dos gens gametofíticos com referência especial ao milho

1) The first part deals with the different processes which may complicate Mendelian segregation and which may be classified into three groups, according to BRIEGER (1937b) : a) Instability of genes, b) Abnormal segregation due to distur- bances during the meiotic divisions, c) obscured segregation, after a perfectly normal meiosis, caused by elimination or during the gonophase (gametophyte in higher plants), or during zygophase (sporophyte). Without entering into detail, it is emphasized that all the above mentioned complications in the segregation of some genes may be caused by the action of other genes. Thus in maize, the instability of the Al factor is observed only when the gene dt is presente in the homozygous conditions (RHOADES 1938). In another case, still under observation in Piracicaba, an instability is observed in Mirabilis with regard to two pairs of alleles both controlling flower color. Several cases are known, especially in corn, where recessive genes, when homozigous, affect the course of meiosis, causing asynapsis (asyndesis) (BEADLE AND MC CLINTOCK 1928, BEADLE 1930), sticky chromosomes (BEADLE 1932), supermunmerary divisions (BEADLE 1931). The most extreme case of an obscured segregatiou is represented by the action of the S factors in self stetrile plants. An additional proof of EAST AND MANGELSDORF (1925) genetic formula of self sterility has been contributed by the studies on Jinked factors in Nicotina (BRIEGER AND MANGELSDORF (1926) and Antirrhinum (BRIEGER 1930, 1935), In cases of a incomplete competition and selection between pollen tubes, studies of linked indicator-genes are indispensable in the genetic analysis, since it is impossible to analyse the factors for gametophyte competition by direct aproach. 2) The flower structure of corn is explained, and stated that the particularites of floral biology make maize an excellent object for the study of gametophyte factors. Since only one pollen tube per ovule may accomplish fertilization, the competition is always extremely strong, as compared with other species possessing multi-ovulate ovaries. The lenght of the silk permitts the study of pollen tube competitions over a varying distance. Finally the genetic analysis of grains characters (endosperm and aleoron) simpliflen the experimental work considerably, by allowing the accumulation of large numbers for statistical treatment. 3) The four methods for analyzing the naturing of pollen tube competition are discussed, following BRIEGER (1930). Of these the first three are: a) polinization with a small number of pollen grains, b) polinization at different times and c) cut- ting the style after the faster tubes have passe dand before the slower tubes have reached the point where the stigma will be cut. d) The fourth method, alteration of the distatice over which competition takes place, has been applied largely in corn. The basic conceptions underlying this process, are illustrated in Fig. 3. While BRINK (1925) and MANGELSDORF (1929) applied pollen at different levels on the silks, the remaining authors (JONES, 1922, MANGELSDORF 1929, BRIEGER, at al. 1938) have used a different process. The pollen was applied as usual, after removing the main part of the silks, but the ears were divided transversally into halves or quarters before counting. The experiments showed generally an increase in the intensity of competition when there was increase of the distance over which they had to travel. Only MANGELSDORF found an interesting exception. When the distance became extreme, the initially slower tubes seemed to become finally the faster ones. 4) Methods of genetic and statistical analysis are discussed, following chiefly BRIEGER (1937a and 1937b). A formula is given to determine the intensity of ellimination in three point experiments. 5) The few facts are cited which give some indication about the physiological mechanism of gametophyte competition. They are four in number a) the growth rate depends-only on the action of gametophyte factors; b) there is an interaction between the conductive tissue of the stigma or style and the pollen tubes, mainly in self-sterile plants; c) after self-pollination necrosis starts in the tissue of the stigma, in some orchids after F. MÜLLER (1867); d) in pollon mixtures there is an inhibitory interaction between two types of pollen and the female tissue; Gossypium according to BALLS (1911), KEARNEY 1923, 1928, KEARNEY AND HARRISON (1924). A more complete discussion is found in BRIEGER 1930). 6) A list of the gametophyte factors so far localized in corn is given. CHROMOSOME IV Ga 1 : MANGELSDORF AND JONES (1925), EMERSON 1934). Ga 4 : BRIEGER (1945b). Sp 1 : MANGELSDORF (1931), SINGLETON AND MANGELSDORF (1940), BRIEGER (1945a). CHROMOSOME V Ga 2 : BRIEGER (1937a). CHROMOSOME VI BRIEGER, TIDBURY AND TSENG (1938) found indications of a gametophyte factor altering the segregation of yellow endosperm y1. CHROMOSOME IX Ga 3 : BRIEGER, TIDBURY AND TSENG (1938). While the competition in these six cases is essentially determined by one pair of factors, the degree of elimination may be variable, as shown for Ga2 (BRIEGER, 1937), for Ga4 (BRIEGER 1945a) and for Spl (SINGLETON AND MANGELSDORF 1940, BRIEGER 1945b). The action of a gametophyte factor altering the segregation of waxy (perhaps Ga3) is increased by the presence of the sul factor which thus acts as a modifier (BRINCK AND BURNHAM 1927). A polyfactorial case of gametophyte competition has been found by JONES (1922) and analysed by DEMEREC (1929) in rice pop corn which rejects the pollen tubes of other types of corn. Preference for selfing or for brothers-sister mating and partial elimination of other pollen tubes has been described by BRIEGER (1936). 7) HARLAND'S (1943) very ingenious idea is discussed to use pollen tube factors in applied genetics in order to build up an obstacle to natural crossing as a consequence of the rapid pollen tube growth after selfing. Unfortunately, HARLAND could not obtain the experimental proof of the praticability of his idea, during his experiments on selection for minor modifiers for pollen tube grouth in cotton. In maize it should be possible to employ gametophyte factors to build up lines with preference for crossing, though the method should hardly be of any practical advantage.

Missouri Botanical Garden bulletin.

v.13 (1925)

Contribuição para o conhecimento de dois afídeos do Brasil

São descritos, em minúcias, os afídeos Idiopterus brasiliensis Moreira, 1925 e Phorodon menthae (Buckton, 1876), da família Aphididae.

Psychosoziale Belastungen und Möglichkeiten der Resilienzförderung von Geschwisterkindern chro-nisch kranker und/ oder behinderter Kinder

Diese Arbeit befasst sich mit den psychosozialen Belastungen und Möglichkeiten der Resi-lienzförderung von Geschwisterkindern chronisch kranker und/ oder behinderter Kinder.Ziel ist es, ein umfassendes Bild über den Forschungsstand der „besonderen“ Situation der Geschwister zu skizzieren und einen Ausblick auf ein Präventionsprogramm zur Stärkung der Lebenskompetenzen von Geschwisterkindern zu geben.Dabei wird der Frage nachgegangen, ob die Geschwister potentiellen Risiken, durch die Le-bensumstände der Familie, ausgesetzt sind, die wiederum eine Gefahr für die Geschwister darstellen und sie möglicherweise in ihrer Entwicklung beeinflussen.Mittels einer umfassenden Literaturrecherche sollen die Ergebnisse zusammengetragen werden. Die Grundlage der Recherche basiert auf die Sichtung von Fachbüchern, wissen-schaftlichen Artikeln und Studien bezüglich der Geschwisterthematik.Zusammenfassend kann lässt sich sagen, dass ein chronisch krankes und/ oder behindertes Kind ein Belastungsfaktor für die gesamte Familie darstellt und als eine Einschränkung der Entwicklungsmöglichkeiten der Geschwister betrachtet werden kann. Demzufolge können die Geschwister als eine vulnerable Gruppe gesehen werden, die vermehrte Aufmerksamkeit in der Primärprävention bedarf. Die Risikoforschung zeigt zwar insgesamt inkonsistente Er-gebnisse, dennoch verweist sie darauf, dass die gesunden Geschwisterkinder ein erhöhtes Risiko haben, psychische Probleme zu entwickeln. Nachweislich treten bei den Geschwis-tern häufiger internalisierende und externalisierende Verhaltensauffälligkeiten auf, die die gesundheitsbezogene Lebensqualität beeinträchtigen.Die Ergebnisse verdeutlichen die Notwendigkeit, dass den Geschwisterkindern zukünftig noch mehr Aufmerksamkeit sowohl in der Forschung als auch in der Prävention geschenkt we

Observações preliminares sobre a malformação em inflorescencias de mangueira (Mangifera indica L.) e fungo, alguns insetos e ácaro nelas encontrados

A malformação de inflorescências e o superbrotamento de gemas terminais e axilares de mangueiras dos Estados de São Paulo e Pernambuco são relacionados com o ácaro Aceria mangiferae Sayed, 1946 (Acarina, Eriophyidae) e o fungo Fusarium moniliforme subglutinans, sendo êste último considerado, empíricamente, como o principal agente causal da doença. Varios insetos associados às inflorescências de mangueiras foram coletados: lagarta de Eupithecia sp. (Tephroclystis), (Lepidoptera, Geometriidae, Hydriomeninae); Frankliniella cubensis Hood, 1925 (Thysanoptera, Thripidae); coleopteros pertencentes às familias Nitidulidae e Cryptophagidae.

South American plants, by J. Francis Macbride ... also new Euphorbias by C. F. Millspaugh and Canavalias by C. V. Piper.

v.4:no.4(1925)