Sulla Tossicità del Magnesio e Sul Suo Antagonismo Col Calcio Nelle Piante

Riassunto

L'A. ha coltivato diverse piante, appartenenti ai vari gruppi del regno vegetale, in soluzioni ricche di Mg o di Ca e di Ca + Mg, per osservare l'azione di questi elementi e il loro antagonismo. Ha condotto poi una serie di ricerche isto-patologiche su materiale intossicato da Mg, studiando specialmente il condrioma e la membrana. Infine ha osservato l'azione dei cationi Ca“ e Mg“ sul rigonfiamento delle principali sostanze colloidali, costituenti il plasma e la membrana vegetale.     

Sulla Struttura del Frutto della “Stubborn” L

Novel methods are required to break the seed dormancy of temperate-zone orchids and aid the conservation of rare species. Zeatin is produced in increasing concentrations during the development of pea (Pisum sativum) seeds. We hypothesised that hot water extracts of pea seeds stimulate germination of the orchid Ophrys apifera in vitro, particularly for extractions made during later pea development. Pea seeds, exposed to 0, 3, 6, 9, 12 or 15 days of periodic wetting, were extracted in hot water and the extracts were added to Malmgren's growth medium. Germination of O. apifera on this medium was quantified after 7 months, stimulated by a range of pure hormones. Pea seed extract collected later in pea development (at 6–15 days) inhibited germination of O. apifera. However, extracts taken at 0 and 3 days significantly increased germination from 3.8 ± 0.32% in the control to 9.1 ± 1.84% and 7.6 ± 0.79%, respectively: increases comparable to the most effective of the pure hormones. Dried peas therefore provide an economical alternative source of germination stimulants for orchids. We briefly report how sufficient mature plants of O. apifera were produced to allow a population to be multiplied to 15 times its original size during a habitat restoration project.     

Ulteriori Osservazioni Sulla Variabilità Del Legno Secondario in Prunus Persica Stokes

Abstract

Further observations on the variability of the secondary wood of PRUNUS PERSICA Stokes. — The length of both fibres and vessel members and the age of cambium in the trunk of a wild specimen of Prunus persica are positively correlated; no relation exists between the length of the above mentioned elements and the width of growth layers.

The relation between the intrasive growth of fibres and either age of cambium or width of growth layers has been also calculated but no significant relation has been attained.

The results have been compared with those obtained in the previous study of a trunk of a grafted Prunus persica, which are very different and quite peculiar mainly as to a decrease in length of fibres and vessel members with aging of cambium. The growing practice to which the tree may have been subjected is regarded as the possible cause of this peculiarity.     

Sulla variabilità cromatica dei fiori nelle specie di Crocus L. delle Alpi sudorientali italiane

Abstract

Chromatic variability of tepals in species of Crocus L. of South-eastern Alps.—The anthocyanidins causing the color of tepals of some species of Crocus L. in the Italian South-eastern Alps were determined and characterized. The genus Crocus of this region is represented by four entities: C. napolitanus Mord. & Loisel., C. albiflorus Kit. ex Schult., C. reticulatus Stev. ex Adam. and C. weldenii Hoppe ex Baker.

The distribution of anthocyanidins in the four entities confirms the existence of a systematic distance among the species belonging to Reticulati and the species belonging to Anulati. Two anthocyanidins, i.e. delphynidin and petunidin, which are always present in other entities, have not been found in C. weldenii; this species is characterized by the only presence of malvidine.

The anthocyanidins assume therefore in this case a chemotaxonomic meaning.     

Attività UDPG pirofosfatasica in Cucurbita e suo possibile rapporto con l'utilizzazione del galattosio

Abstract

UDPG-PYROPHOSMIATASE ACTIVITY IN CUCURBITA AND ITS POSSIBLE ROLE IN GALACTOSE UTILIZATION. — Preparations obtained by ammonium sulfate precipitation from homogenates of Cucurbita maxima tissues catalyze the hydrolysis of UDPG to UMP and Gl-l-P. The same tissues contain all the enzymes implicated in galactose metabolism, with the exception of Gal-l-P-uridyltransferase. Therefore the possibility is suggested that the UDPG-pyrophosphatase found may play an important role in the conversion of galactose to the phosphate esters of glucose. This suggestion is also supported by the finding that the amount of activity found in homogenates could account for the respiratory activity of the tissues if glucose arising from galactose were the main respiratory substrate.     

Ist die Beibehaltung einer Gattung Torulaspora berechtigt?

Ohne Zusammenfassung     

Aumento di viscosità del succo delle uova di Bombyx mori in seguito a riscaldamento

Riassunto Il succo di uova di Bombyx mori, riscaldate a 50° C per mezz'ora, all'inizio della svernatura, mostra un cospicuo aumento di viscosità rispetto al controllo. Dopo circa due mesi le uova riscaldate forniscono succo ancora notevolmente più viscoso del controllo. L'esame dei dati viscosimetrici mostra che durante questo tempo vi è stata una regolazione viscosa, ma imperfetta, che si può stimare con approssimazione del 43,17%. Anche ammettendo che si giunga ad avere una regolazione completa, è- da supporre che l'ambiente anomalo, in cui per un tempo così lungo viene a trovarsi l'embrione, non sia senza effetto su di questo e possa indurre sul futuro organisme somazioni o vere mutazioni.

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Zusammenfassung Preßsaft von Eiern von Bombyx mori, bis auf 50° für eine halbe Stunde lang erwärmt, zeigt eine entschieden größere Viskosität als der von Kontrolleiern. Ungefähr 2 Monate lang bleibt diese Viskosität gleich, trotzdem schlüpfen die Eier zu 100%. Die erhöhte Viskosität entsteht wahrscheinlich durch Dishydratation der Eier oder durch Veränderungen in der Micellärstruktur der proteischen Komplexe.Diese erhöhte irreversible Viskosität erlaubt in jedem Fall die normale Entwicklung der Eier.Es erscheint möglich, daß eine irreversible Änderung eines chemischphysischen Charakters des Cytoplasmas, wie die beschriebene, der Grund einer Mutation sein kann, indem sie auf die Chromosomen wirkt und das Cytoplasma, in welchem die Chromosomen arbeiten, verändert.