Page:The New International Encyclopædia 1st ed. v. 18.djvu/642

* STEM. 548 STENDHAL. the stele determines the three general and most fundamental types of vascular stems. In the dicotyledon and conifer types (Fig. 3) the woody bundles are arranged in a hollow cylinder sur- rounding a central pith. Around the woody tissue of perennial stems there is developed a layer of actively dividing cells, the cambium, that adds a new outer zone of woody bundles each growing season, in cross-section giving the ap- pearance of concentric annual rings. This power of increasing in diameter is one of the prominent features of these stems. In the monocotyledon type (Fig. 4) the woody bundles are scattered irregularly through the stele, as in the corn- stalk and palm, so that there is no defined cen- Tig. 5. bbaxch of cactus (Opuntia. arboreseens), grown IX THE DARK. The stem form above differs from the normal Btem below in general shape, in the loss of protuberances and epine^, and in the gain of leaves. tral pith region. Such stems show no annual increase in diameter. In the pteridophyte type usuallv a single large woody bundle of peculiar structure appears in the stele, in such a way that there can be no annual increase in diameter. The primary function of the stem is to develop foliage leaves and display them to the air and sunlight, and also to act as a great conducting region between the root system and the leaves. (See Conduction.) Subsidiary functions are vegetative propagation (as in horizontal ground stems) ; the storage of foods (as in bulbs and tubers) ; and the manu- facture of foods, as in leafless stems, such as Equisetum and the cacti. Among the external factors which inlluence stem development, light and moisture arc perliaps most important. In general, light is thought to retard stem develop- ment, as seen when stems grown in full light are compared with those grown in weak light and in the case of tubers. In some cases, however, as Fig. G. branches of gorse (Ilex Europ^us). Showing the iniluenee of moisture: the spiny branch, at the right grew in dry air, the other branch in moist air. in the cacti, light has been found to favor stem development. Experiments seem to show that much of the so-called influence of light is due to a moisture influence (Fig. 6). STEM-GIRDLEE, A horn-tail fly (Phylloe- CHS flariventris) which with its ovipositor girdles the twigs of currant bushes and deposits an egg below the cut. The resulting larva bores down- ward into the pith, which it devours, with the adjacent woody portion of the stem. In the autumn it spins its cocoon in the burrow, trans- forms to a pupa in the following spring, and shortly after emerges. An allied species (PhyUoe- cus integer) works similarly in willows. Sec WiLi.ow Insects. STENDAL, sten'dal. A to^vn in the Province of Saxony, Prussia, on the Uchte, 36 miles north- northeast of ^Magdeburg (Map: Prussia, D 2). It has a fifteenth-century late-Gothic cathedral restored in 1893. There are railway repair shops, and factories for ii'on furniture, cloth, gilt cor- nices, agricultural implements, and sugar. Sten- dal, founded in the twelfth century, was the capital. of the Altmark of Brandenburg. Popu- lation, in moo. 22.081. STENDHAL, stiiN'dal'. The name assumed by M.^RiE Hexki Beyle (1783-1842). A French novelist remarkable for the keenness of his analysis of character. Though never popular, Stendhal has been much read and admired by