Tori in wood of Osmanthus americanus, Daphne odora, Celtis occidentalis and Ulmus alata were tested for lignins using KMnO4 staining in conjunction with TEM, and acriflavine staining in concert with CLSM. It was hypothesized that impregnation with lignin could explain torus survival during cytoplasmic apoptosis. KMnO4 staining indicated torus lignification in all four woods, whereas only Osmanthus and Daphne tested positive for lignin with acriflavine. Tori in Celtis and Ulmus showed some evidence of partial breakdown during cell maturation, which might expose non-lignin sites for KMnO4 binding and thus produce spurious results. The acriflavine data correlate with developmental studies in which torus ontogeny occurs by one method in Osmanthus and Daphne and by another method in Celtis and Ulmus.

In: IAWA Journal

A torus is present in intervascular pit membranes in the wood of Daphne odora and D. cneorum, but not in D. mezereum. In the two former species, each torus is surrounded by a margo consisting of fibrillar material in a tightly woven pattern. Tori are of greater diameter than pit apertures and completely occlude the apertures during aspiration. Evidence from D. odora indicates that torus deposition is spatially associated with vesicles and a plexus of microtubules, and does not begin until pit border formation is complete. The material deposited during torus synthesis also impregnates the wall of the pre-existing pit membrane. The plasmalemma often is closely appressed to the pit membrane at the site of the developing torus. In half-bordered pit pairs between tracheary elements and parenchyma cells, a torus thickening is deposited only on the side of the tracheary element. As in Osmanthus americanus, it is hypothesised that the presence of tori in species of Daphne prevents rupture of the pit membrane during aspiration.

In: IAWA Journal

Intervascular pit membranes of Cercocarpus possess torus thickenings. The thickenings, or pads, consist of lignified, secondary wall material. Torus pad deposition occurs late in cell ontogeny and is not associated with a microtubule plexus. Half-bordered pit pairs between tracheary elements and parenchyma cells often have a torus pad on the membrane surface facing the conducting cell. In contrast, a thick protective layer fills the pit cavity on the side of the parenchyma cell. Ontogeny of the torus thickenings in Cercocarpus represents a third mode of torus development in eudicots when compared to that occurring in Osmanthus/Daphne and Ulmus/Celtis.

In: IAWA Journal

The development of the torus in the wood of Osmanthus americanus was investigated using transmission and scanning electron microscopy. Torus formation on either side of the pit membrane did not begin until after the development of the associated pit border was well underway. No plasmodesmata were encountered in the torus at any time during its ontogeny. Synthesis of torus material was correlated with a mass of randomly oriented microtubules and dictyosome vesicles. The two halves of the torus did not develop synchronously; deposits of torus material were evident first in the older of two adjacent cells. Selective hydrolysis of the matrix material of the margo also began fIrst on that side of the pit membrane associated with a mature tracheary element. Evidence is presented for a fibrillar as weIl as a matrix component in the torus.

In: IAWA Journal

Torus thickenings of pit membranes are found not only in gymnosperms, but also in certain genera of dicotyledons. One such genus is Osmanthus. Wood from 17 species of Osmanthus was searched for tori. Fourteen species from three of the four sections investigated possessed these thickenings. Ten of the species represent new records. Only the three New Caledonian species of Section Notosmanthus lacked tori. This observation in combination with other factors serves to isolate this section from the remainder of the genus.

In: IAWA Journal

Osmanthus armatus Diels is a member of the Oleaceae whose woody branches were previously found to possess torus-bearing pit membranes. Observations of the perennial leaves indicate that torus-bearing, pitted tracheary elements extend throughout the vasculature of the organ including the veins delimiting the areoles and the vein termini. Torusbearing tracheary elements differentiate into the vein termini but do not develop at the very ends. Rather, the distal ends of vein termini consist of tracheids without tori and of phloem containing intermediary cells. The latter cell type is a component of the phloem in the small diameter leaf veins. Tori are considered to be xeromorphic features which, along with a thick cuticle and sclereids, are advantageous for the perennial growth habit of the leaves.

In: IAWA Journal
The Ṣāliḥiyya Quarter from the Twelfth to the Twentieth Centuries
Author: Toru Miura
This book presents a new perspective on Islamic urban society: a dynamism of social networking and justice which caused both rapid development and sudden decay in the Ṣāliḥiyya quarter. Founded in the northern suburbs of Damascus by Hanbali ulama who migrated from Palestine to Syria in the mid-12th century, the quarter developed into a city through waqf endowments. It has attracted the attention of historians and travelers for its unique location, popular movements and religious features. Through the study of local chronicles, topographies and archival sources and through modern field research, Toru Miura explores the history of the Ṣāliḥiyya quarter from its foundation to the early 20th century, comparing it to European, Chinese and Japanese cities.

Pit membranes between tracheary elements of Ulmus alata, Celtis laevigata, and Celtis occidentalis often contained tori. The degree of development of tori varied and was greatest in those membranes connecting elements of small diameter. Complete tori consisted of two wall thickenings adjoined by a central layer. In three dimensions the shape of the torus often approximated a grooved wheel. Initiation of thickening in the pit membrane occurred first on the side of the older cell and was well underway prior to the beginning of secondary wall synthesis. Torus formation resulted from the thickening of the primary walls of the pit membrane. Development of the torus was associated with membranous vesicles and cisternae but not with microtubule complexes as was reported in Osmanthus. The pit membranes in this study are capable of aspiration, and the tori may prevent rupture of the pit membrane during this process.

In: IAWA Journal

Atomic force microscopy was used to compare the structures of dried, torus-bearing pit membranes from four woody species, three angiosperms and one gymnosperm. Tori of Osmanthus armatus are bipartite consisting of a pustular zone overlying parallel sets of microfibrils that form a peripheral corona. Microfibrils of the corona form radial spokes as they traverse the margo. Margo microfibrils are loosely packed thus facilitating passage of water molecules. The pustular layer is removed by acidified sodium chlorite. Tori of Cercocarpus montanus also have a pustular surface, but lack a corona. Tori of Pinus taeda have a finely granular to amorphous torus matrix. Ulmus alata tori have microfibrils traversing the surface. The atomic force microscope proves itself a useful tool for high resolution study of pit membranes with only minimal specimen preparation.

In: IAWA Journal

[German version] Latin term (Greek τύλη/týlē; τυλεῖον/tyleîon) for anything raised or bulge-like, such as the convex circular parts of an Ionic column base (Column [II B 3] with ill.; the term entered mediaeval and modern architectural terminology in the form (torus) usual in Vitr. De arch. 3

In: Brill's New Pauly Online