Effetto di Popolazione tra Espianti di Helianthus Tuberosus

Abstract

Population effect among explants of jerusalem artichoke. — We found that among explants of Jerusalem artichoke cultured « in vitro » are not present positive population effects, as reported by others A.A.     

Processi di Neoformazione di Mitocondri Nella Cellula Vegetale

Abstract

Processes of formation of new mitochondria in plant cells. — While studying with the electron microscope the quiescent centre in the onion (Allium cepa) root tips, the writer was able to observe the endoplasmic reticulum arranged into peculiar concentric ring systems, which are here described. In some of the ring structures, between a ring and the contigous one, mitochondria-like bodies are formed, which are then detached by a kind of budding process. A short review of the current literature on formation of the mitochondria is also reported.     

Osservazioni sulla microflora fungina di ceppaie di abete bianco

Abstract

Mycoflora of Silver fir (Abies alba Mill.) stumps. - This work is a first contribution to the knowledge of the mycoflora colonizing Silver fir (Abies alba Mill.) stumps in Italy.

Autochthonous fungal species were isolated from the wood of A. alba stumps from three different sites in the Tuscan Apennines.

Frequency values for the isolated species and taxonomic groups were calculated.

Deuteromycetes (57–82.5%) occurred more frequently than basidiomycetes (5–36%), phycomycetes (0.7–11.6%) and ascomycetes (0–1%). The most common genera were found to be: Aleurodiscus, Penicillium, Phellinus, Phialophora, Scytalidium, Sistotrema and Trichoderma.

An effective method of isolation from wood is also described.     

Assunzione di Fosforo32 da Parte di Cuscuta Epithymum Parassita di Trifolium Repens

Abstract

Uptake of Phosporus-P³² by CUSCUTA EPITHYMUM parasitic of TRIFOLIUM REPENS. — Filaments of C. epithymum, parasitic on T. repens, partially immersed in a solution containing KH₂P³²O₄, uptake from the host solely, or mainly, radioactive ortophosphate. Radioactive hexose phosphates and radioactive nucleotides present in the extracts prepared from C. epithymum, appear to be the result of the metabolization by the dodder of the orthophosphate uptaken from the host.     

Fenomeni di Inattivazione e di Riattivazione Enzimatica in Endospermi di semi di Ricino

Abstract

Inactivation and riactivation of enzymes in endosperms of castor bean seeds. — On the basis of previous results, the possibility has been investigated of the reversible interconversion of active and inactive form of enzymes in castor bean seeds, during their development.

The results described here indicate that:

1. the activity of some glycolytic enzymes increases greatly (81% and 400% increase of, respectively, Gl-6-P-dehydrogenase and aldolase) upon incubation of dry seeds for few hours at 4 °C.

2. The decrease of enzyme activity upon dehydration of seeds and the increase during the subsequent imbibition can be shown reproducibly.

3. This same observation is made for oxygen uptake.

These results are interpreted to indicate the reversible inactivation of enzymes caused by dehydration of seeds.     

Cultura in Vitro di Ovuli di Pinus Pinea L.

Abstract

Pinus Pinea ovules cultured in vitro. — The degree of growth and autonomical differentiation of Pinus pinea L. proembryo has been studied by means of controlled cultures in vitro of excised ovules.

Proembryos in vitro undergo involution and initials of their growth points change back into parenchimatoides cells.

Completely differentiated embryos cultivated in vitro behave as if they were not physiologicaly ripe in all their parts. Embryos cultured in august, september and october develop into rocotless seedlings. Only embryos cultured in november have roots able to elongate where germinating, but in a still scarce degree in comparison with hypocotile and cotiledons. Hypocotil root ratio is inverted as regards what happens in nature.

The primary endosperm of Pinus pinea L. cultivated in vitro undergoes surface diffuse proliferation.

A case of polyembriony has been observed.     

Tecniche di Coltura di Semi di Grano Sottoposti ad Operazioni di Trapianto Embrionale

Abstract

Cultural techniques for wheat seeds submitted to embryo transplantation. — The author, on the basis of his experience coming from the work carried out on the embryo transplantation for several years, takes in consideration some aspects, at technical level, regarding the best way to cultivate wheat seeds submitted to embryo transplantation operations.

In particular, the author refers on the possibility to sow the transplants just made (while the traditional method foresees the drying of transplants for 48–96 hours under laboratory conditions) and he illustrates the results of the transplant culture in jiffypots, which allow to improve survival of materials intended for the growth in field.     

Ricerche Sull'ultrastruttura dei Tubi Cribrosi di Piccioli di Foglie di Edera

Abstract

The ultrastructure of sieve tubes in leaf petioles of HEDERA HELIX. — The structural organization of the sieve elements in Hedera leaf petiole at the beginning of the second year of life has been studied. At this stage of life the sieve tubes are completely developed, but still in full activity.

Their plasmatic structures, though altered, show that they are still alive. The cytoplasm forms a parietal layer; mitochondria, endoplasmic reticulum and plastids are present although very peculiar in aspect. The cytoplasm is bounded externally by a plasmalemma; on the contrary no tonoplast is detectable.

The data reported in this paper are favourable to the idea of an active partecipation of the sieve tubes in the translocation of organic solutes, in agreement with the findings concerning the oat coleoptile.     

Effetto Dell'attinomicina Sulla Crescita di Alcune Specie di Alghe

Abstract

Action of Actinomycin on the growth of Algae. — Actinomycin C inhibits the growth of two strains of Euglena gracilis, of Chlorella vulgaris, of Prototheca zopfii and of Scenedesmus sp. The growth inhibitory effect is evident on both autotrophically and heterotrophically grown cultures. DNA extracted from C. vulgaris appears to form a complex with Actinomycin C similar to that observed in the case of other organisms.     

I piani di vegetazione in Italia

Abstract

Vertical zonation of vegetation in Italy. – A revision of the scientific terms used by Italian botanists for the vertical zonation of vegetation reveals some inconsistencies and allows to propose an alignement with the nomenclature used in English and proposed already during the International Botanical Congress of 1910: Belt (ital.: fascia) for the topographical zonation and zone (ital.: zona) for the geographical zonation. Italy belongs to two zones: the mediterranean and the medioeuropean one. A scheme of vegetation belts in both of the zones is proposed. The indications subalpine and montane are substituted by boreal and subatlantic.     

Ricerche Sui Fenomeni di Contrazione di Mitocondri Isolati di Internodio di Pisello

Abstract

Study on the contraction phenomena of isolated mitochondria of pea internodes. — The action of the phosphorylative inhibitors atractylate and oligomycin on ATP-induced contraction of isolated pea mitochondria has been studied. Oligomycin has proved to be an efficient inhibitor of mitochondrial contraction; no effect is seen on the contrary upon addition of atractylate. Both atractylate and oligomycin inhibit completely oxygen consumption of mitochondria with succinate as substrate. On the base of these results it is postulated that the two inhibitors act upon different sites of the phosphorylative reaction sequence.     

Forme Nuove di Arisarum Vulgare Targ. Tozz

Riassunto

L'autore, facendo delle ricerche sulla variabilità individuale nel numero dei fiori maschili e femminili dell'Arisarum vulgare, ha trovato alcuni casi teratologici e identificato e descritto le seguenti forme nuove: A. viridescens, A. Negrii, A. Pampaninii, A. Passerinii, A. Rovestii.     

Fissazione di CO2 da Parte di Entomocecidi di Cuscuta Australis

Abstract

Fixation of carbon dioxide by galls of CUSCUTA AUSTRALIS. — The mechanism of the carbon dioxide fixation by Cuscuta is a controversial biochemical topic. Light induced reactions are involved in MacLeod's opinion while others as Ciferri and Poma believe that mainly a dark-fixation occurs.

In this study use is made of the galls, caused by the insect Smicronyx on Cuscuta australis, that appear more green coloured than the normal tissues.

Equal weights of excised galls were kept both in light and in darkness in contact with C¹⁴O₂for different incubation times, and the magnitude of the fixation was compared under these two conditions by measuring radioactivity of both soluble and acid hydrolysed fractions.

After short exposures to the tracer the fixation in light greatly exceeds that in dark (25–19/1) while with more prolonged exposures the ratio sharply decreases (to about 5/1): these figures can be interpreted with the assumption that a strong light-induced fixation superimposes itself to a low but definite dark-fixation activity.

The ratio does not change if radioactivity is measured in the hydrolysed fractions.

These results are of course referred to as being largerly preliminar and requiring further and more extensive studies.     

Residui di vegetazione spontanea in Roma

Summary

The A. describes a large remainder of natural vegetation at the periphery of Rome on the «Monti Parioli». Mainly it is Quercus Ilex macchia — evergreen wood, which becomes on the septentrional declivities Quercus Ilex — Quercus lanuguinosa mixed wood; here among the shrubs some not typical mediterranean elements are contained.     

Azione della luce sulla crescita allo stadio di plantula di un mutante clorofilliano di Triticum durum Desf

Abstract

ACTION OF LIGHT ON SEEDLING GROWTH IN A YELLOW-GREEN MUTANT OF TRITICUM DURUM DESF. — Dry grains of Triticum durum cv. « Cappelli » and its radiation-induced yellow-green mutant were sown in sand in four environment, different for light conditions (daylight, artificial light, ultraviolet rays, darkness), having all the same temperature (23°C.). Seven days after sowing, the following data were registered: a) growth (in cm.) of the shoot and of the longest root; b) fresh weight (in gr.) of shoots and roots; c) water content of shoots and roots.

The following main results were obtained:

1. the yellow-green mutant always shows less growth and less weight increase than normal « Cappelli », with the exception of the seedlings grown at daylight, which have shorter shoots and longer roots than the normal « Cappelli » but the same weight:

2. artificial light, besides depressing the growth of the roots of the yellow-green mutant, which becomes green under these conditions, induces a remarkable decrease in the water content of the roots of the two wheats.

     

Il Comportamento del Nucleolo di “Paphiopedilum Spicerianum„ (Rchb. f.) Pfitz. di Fronte a Fissatori di Tipo Diverso

Riassunto

L'A. descrive il comportamento del nucleolo di Paphiopedilum Spicerianum nel nucleo in riposo c in divisione, mettendo in evidenza l'esistenza di una sostanza nucleolare, conservata in seguito a fissazione' del materiale con una miscela di acido cromico e formolo, con postcromizzazione in acido cromico.     

Analisi polliniche di fanghi di acquitrini della Pania di Corfino,nell'Appennino Lucchese

Abstract

Pollen analysis of the sediments of a bog on the slopes of Panià di Corfino (Apennines, near Lucca). Fossil pollens in the sediments of a bog situated on the slopes of Pania di Corfino (Lucca) have been studied. The site studied lies on oligocenic rocks and is surrounded by beeches.

From a depth of 120 cm up to 50 cm the prevailing pollens belong to species typical of beech and silver-fir woods. Layers from 50 to 25 cm contain mostly pollen of herbaceous plants and of Ericales shrubs, especially belonging to the genus Vaccinium. The upper layers (25 to 5 cm) show a prevalence of Pinus mugo pollen. These data suggest that, after a long period during which climatic conditions resembled those of the present, a shift to a colder climate lowered the upper limit of the beechwoods.     

Frammenti di Quereeto a Roverella e di Macchia Mediterranea a Vivara (Isole Flegree)

Abstract

Fragments of oak-crop with QUERCUS PUBESCENS willd. and of mediterranean maquis in the isle of vivara (Flegrean isles). — In these note the types of arboreous and shrubby vegetation pointed out in the islet of Vivara are passed in rapid review. Particular references to the types of vegetation arranged in the Quercion ilicis are given.

A short account is reserved to the presence of Quercus pubescens Willd. and to the importance of these species concerning the construction of the fragments of oak-crop and of mediterranean high maquis that are present to the edges of tableland and on the sides of the smallest Flegrean isles.

It is a question of unusual aspects of vegetation for a microinsular environment. Therefore they are worthy of study before they are destroyed or still more altered.     

Residui di Leccete pure e miste sulla Murgia di Putignano

Summary

Purpose of this paper is to point out the residues of Quercus Ilex woods in the hilly region of Murgia di Putignano (Puglia) which lies inside the distribution area of Q. trojana, now the main wood-forming tree-species of this territory.

Fourteen different small Q. Ilex stands are mentioned, as marked on alleged map. One of them (n° 1 on the map) has been more carefully studied through a whole year, and all plants growing in it have been collected.     

Embriologia di Ulmus campestris L

Riassunto

L'A. stabilisce die in Ulmus campestris L. lo sviluppo del gametofito femminile avviene secondo due distinti tipi di sviluppo tetramegasporiali bipolarizzati: 1) gametofiti 10, 12 e 14-nucleati con oangio monosporiale che si costruiscono per polarizzazione 1+3 dei nuclei sporiali; 2) gametofiti 8-nucleati con oangio disporiale del tipo Adoxa.

Stabilisce inoltre che la frequenza di sviluppo dei due tipi oscilla intorno ai valori percentuali del 65% e 35% rispettivamente.

Il grado molto elevato di frequenza dei gametofiti 10-nucleati, finora ignoti nella letteratura embriologica, offre all'A. l'opportunità di discutere sul significato e gli attributi del tipo generale Pyrethrum parthenifolium 16-nucleato; il sottotipo Ulmus 10-nucleato, e i sottotipi Tanacetum 12- e 14-nucleato devono esser considerati come sottotipi di riduzione ad esso subordinati.

Durante lo studio della microsporogenesi e dello sviluppo del gametofito femminile è stato riconfermato per questa specie il numero aploide dei cromosomi n = 14. Sono state oservate varie anomalie nella differenziazione dei granuli pollinici, causate da fattori climatici.