ORIGIN AND DEVELOPMENT OF SCLEREIDS IN THE FOLIAGE LEAF OF TROCHODENDRON ARALIOIDES SIEB. & ZUCC.

Sclereid Formation in the Shoot of Pseudotsuga taxifolia

“…) tion), the adjacent cells of the pith also seem to DISCUSSION.-The ontogeny of the idioblast in elongate, pushing aside from their previous posi-Douglas fir recalls markedly the development of tions. In this manner, the originally orthogonal similar elements in Trochodendron (Foster, 1945) Fig. 10-l9.-Fig.…”

“…always grow along the middle lamella. In noted to occur in Camellia (Foster, 1944) and longisections of the pith, these arms can be seen to Trochodendron (Foster, 1945); nor are there em-develop in all directions, with the majority of the bedded crystals in the wall, as appear to be charac-processes, however, taking a vertical course. In teristic of the idioblasts of Agathis and A raucaria transection, the invasion of vertical intercellular (Bertrand, 1874;Lopriore, 1905;Mohl, 1871; spaces between the rounded parenchyma cells is Seward and Ford, 1906;Solms-Laubach, 1871), immediately apparent.…”

“…. THE INVESTIGATIONS of Foster (1944Foster ( , 1945 and Bloch (1946) have indicated some of the major problems concerned in sclereid ontogeny. The intermittent differentiation of isolated idioblasts, which is characteristic of many plant organs, raises questions not only in the field of histogenesis, but also properly in the realm of physiology.…”

“…[Vol. 34, and Camellia (Cavara, 1897;Foster, 1944). The first apparent indication of sclereidal initiation in all these forms (and in Monstera, Bloch, 1946) is an enlargement of the nucleus and a change in the disposition and stainability of the cytoplasm.…”

Microfibrillar Arrangement in Developing Fibers of Asparagus

“…Likewise, the structure of the tips of asparagus fibers and the uniform wall thickness along their lengths speak against the hypothesis that gr?wth is restrict~d to the cell ends. Contradictory evidence to the tip-growth hypothesis is provided also by wall growth in sclereids (Foster, 1945;Sterling, 1947), in cotton fibers (O'Kelley, 1953), and in parenchyma and epidermal cells of Avena coleoptiles (Wardrop, 1956).…”