A course on practical elementary biology - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ... in the opposite direction, now appears in the initial cell, forming with the first wall a cell the shape of a truncated cone, perpendicular to the surface, and with its larger end outwards. This is the Mother-cell of the stoma, the remaining horseshoe-shaped portion of the initial cell being a Subsidiary Cell. The mother-cell is next bisected by a formed, and cuts off from an epidermal cell the Initial Cell of stomata in the cotyledon of Lamium album, a, initial cell; b, mother-cell of stoma; c, d, guardcells i e, subsidiary cell. Fig. 136.--Transverse section through the middle of the hypocotyl of Lamium album, end, endodermis; per, pericyde; phi, phloem; xy, xylem. perpendicular wall, and a cleft appearing in this completes the formation of the stoma. 56. Prepare transverse sections from about the middle of the hypocotyl of a young seedling. Clear, and examine. There are two bundles contained in an axial cylinder as in the root. A layer of endodermis, whose lateral walls when young show the characteristic dot, surrounds the cylinder. Within this is the pericycle. Xylem and phloem are on alternate radii. Very early in the life of the seedling the two xylem masses meet in the centre of the hypocotyl; the phloem spreads out laterally. 57. Prepare transverse sections of the stalk of a cotyledon, and examine. There is a single vascular bundle in a flattened band running through the middle of the stalk. The middle of the band is occupied by the oldest wood vessels (spiral and annular), to the right and left are younger ele only is figured, phi, phloem; xylem." ments Qf and outside these, still further to the right and left, are the phloem strands. The arrangement, therefore, is different from that which obtains either in the stem or root. 58. Cut a series...