Studio Anatomico-Ecologico del Legno Secondario di Alcune Piante del Fezzan

Riassunto

L'A. studia il tessuto legnoso secondario di 18 specie desertiche Fezzanesi, dando di ciascun legno una descrizione micrografica completa. I caratteri anatomici ed ecologici dei legni studiati suggeriscono la sistemazione delle specie a cui essi appartengono in quattro categorie ecologiche diverse.

L'A. discute poi le caratteristiche ecologiche-anatomiche delle specie appartenenti a ciascuna categoria ed il loro diverso grado di adattamento alla vita in ambiente desertico (1).     

La Linnaea Borealis L. Nel Versante Occidentale del Parco Nazionale Dello Stelvio

Abstract

LINNAEA BOREALIS L. on the occidental slope of the Stelvio National Park. — Distribution of Linnaea borealis L. is here examined within territorial limits of the occidental slope of the National Park on the Stelvio, taking out and noticing, for many stations characteristics of association in which the plant has beenobserved.     

Stazioni Eterotopiche di Saxifraga Incrustata Vest. nel Carso Triestino

Abstract

Two abnormal stands of SAXIFRAGA INCRUSTATA Vest, on the Karst of Trieste. — Near of Trieste there are two dolines (sinkholes), where Saxifraga incrustata occurs. The average height of the zone is 300 m above the sea. This unusual presence of a subalpine plant at so low altitude is to relate to a temperature's decrease owing to a very intensive evaporation. In summer time develops a draft between the opposite sides of the dolines and produces the strong evaporation of percolation water in one case and of the imbibition water of a thick moss layer at the other hand.     

Alcune caratteristiche strutturali dei cromosomi politenici del sospensore embrionale di Phaseolus coccineus in due momenti dell'embriogenesi

Abstract

Some features of polytene chromosomes of Phaseolus coccineus suspensor during two stages of early embryogenesis. – The distribution of DNA and RNA puffs in the whole genome of the giant cells of the Phaseolus coccineus embryo suspensor has been detected in two stages of embryo development. The collected data show that the chromosome regions showing the highest frequency of DNA puffs in both analysed stages are the following: i) band B (the fraction proximal to secondary constriction) of chromosome pair I and band E of chromosome pair V. When the two stages of development are however compared, it is seen that the % of DNA puffs in chromosome pair is at least double in suspensors dissected from the first stage of embryo development (86% in the first stage; 41% in the second stage). As to chromosome pair V band E organizes DNA puffs in 36% and in 50% of observed chromosomes in the first and second stage respectively; ii) band A of chromosome pair II, with a frequency of 52% (first stage) and 27% (second stage); iii) band E of chromosome pair VIII (27% in the first stage and 19% in the second stage). As far as the organization of RNA puffs is concerning it seems possible to outline the following values as the highest percentages:

a) First stage. chromosome b) Second stage. chromosome

I: band B 83% I: band B 91% VI: band E 55%

II: band A 70% II: band A 51% band G 50%

IV: band E 45% band C+D 59% VIII: band E 44%

V: band B+C 57% IV: band E 51% IX: band A 54%

band E 71% band G 51% band E 43%

VI: band E 53% band I 51% band F 53%

VIII: band E 43% V: band E 43%

IX: band E 42%

The differences observed between the two stages are discussed in relation to the function of the suspensor.     

Caratterizzazione citologica e citochimica del nefrone di Cyprinus carpio L.

Ricerche eseguite e pubblicate con il concorso di un contributo del C. N. R.     

Analisi polliniche di depositi lacustri delle pendici del M. Vulture in Basilicata

Abstract

Pollen analysis of lake sediments on Mt. Vulture in Basilicata (Southern Italy).—A marshy sediment, about 7 meters thick, containing fossil pollen, has been discovered in a little lake of volcanic origin on a slope of Mount Vulture in Lucania at 656 m above sea level.

The sediment shows four distinct layers from the top to the bottom. The deepest layer, from 7 to 5.75 m, consisting of clay containing Betula and Ostrya, indicates a rather arid climate; the next layer, from 5.75 to 3.75 m, made up of mud rich in organic substance and containing pollen of Fagus and Abies, is witness of a damp and warmer climate; the following layer, from 3.75 to 2.25 m, with clay containing Betula, Ulmus, Ostrya and Corylus suggests a return to a more arid climate; lastly, the upper layer, from 2.25 m to the surface, with marshy mud rich in organic substance and pollen of plants with greater water requirements leads us to think of a return to a damper climate.