Bast, Or Bass, the inner bark (endophlaum) of dicotyledonous plants, contiguous to the woody circle. It is the fibrous part of the bark, and consists of a tissue of cells, including the so-called laticiferous vessels. Less frequently it occurs in the pith and leaves of dicotyledonous, and in the stems and leaves of monocotyle-donous vegetables. It originates out of the cambium (organizing tissue), and belongs to the vascular bundle. The bast cell grows long at the expense of the surrounding parenchyma, without producing new cells. The wood and bast cells of monocotyledonous plants are not easily distinguishable. There are none in the cryptogamous. For the plant itself, as well as for technical, medicinal, and other purposes, the bast cell is of the highest importance. It conducts sap, serves to exchange and alter the vegetable matters, produces nutritious or poisonous or medicative matters, and is largely used in the fabrication of cloth, ropes, mats, sacks, etc. The bast cells are disposed and developed variously in different plants; occurring in rows, wreaths, more or less spread bundles, or single within the parenchyma. In some plants bast is formed but once, in others every year.
Some are simple, others branched; some primary, others secondary; some ever flexible, others changing into wood. They are most developed toward the outside. While young they contain a granulary liquid, which disappears by the thickening of their walls. In the chelidonium majus this liquid remains as yellow milk. The laticiferous cells of the apocynem, euphorbiacece, and compositae (dandelion, lettuce, etc.) are developed just like the fibrous cells of flax. Young bast cells, when treated by a solution of iodine and chloride of zinc, become pale blue, the older ones violet, the full grown pink. Thickened cells are plainly stratified, and their walls often become contiguous by the disappearance of the cavity. The walls exhibit various designs, spiral or other lines, more or less constantly, according to the variety of the plants, and also to the treatment by alkali and acids. By such treatment, and by the microscope, the nature of the various fabrics made of bast may be determined. Thomson and F. Baur have thus demonstrated the sheets around Egyptian mummies to be of linen. The degree of decom-posability, of contraction, of twisting, and the length, density, and form of the single cells of the bast, vary in different plants.
They are very long in flax, hemp, in some nettles, spurges, etc.; very short in cinchona. Cotton consists of long hairs, and not of bast cells, which it very much resembles otherwise. The bast cells of monocotyledonous plants are mostly ligni-fied. The unlignified are very hygroscopic (water-attracting), contain often chlorophyl (the green matter of plants), and more frequently a sort of milk, which is condensed into gum elastic, gutta percha, opium, etc. The lignified, on the contrary, conduct sap but a short time, become filled with air, and thus dead for the plant. No bast cell has pits, but the abietineae have sieve pores or canals. - The uses of bast are manifold. Flax bast is soft, flexible, seldom with swellings; hemp bast is very long, stifler and thicker than flax, more stratified; nettle (urtica dioica) bast resembles cotton, has swellings, and is thicker than hemp. Branched and lignified bast cells of great beauty are those of the mangrove tree (rhizo-phora mangle), and the secondary ones of abies pectinata. Among the monocotyledonous bast fibres, those of the New Zealand flax (phor-mium tenax) are the most remarkable, being found in bundles near the margin of leaves.
They resemble hemp, are very white, sometimes yellowish, very long, and contain much lignine, somewhat stiff, but very tough, and fit for stout ropes. In palms a highly developed body of lignified bast surrounds their vascular bundle, while particular bast bundles are found also in the bark, leaves, and interior of the stem. Of this, the husk of the cocoanut is an example. A similar disposition exists in the draccena refiexa, and in some aroidece. Everybody knows the tenacity of the bast of the linden tree, which is hence also called bass-wood. The Chinese grass cloth is made of bamil, Bozhmeria puya. Manila hemp comes from the musa textilis; rice bags are made in India from antiaris saccidora. The Latin name of bast, liber, was used to signify book, from the use of bast in ancient times for writing on. Our word book also means, originally, beech (fagus), from the same use of its bast before the invention of other materials.