. "On the structure, the occurrence in Lancashire, and the source of origin of Naias graminea, Del., var. Delilei, ;. Botany. ON NAIAS DEL., VAR. DELILEI MAGNUS. 28 in the stem, but much smaller and more circular (see fig. 89). These cavities are regularly arranged in one series round the central mass, as in the stem, but there are occasionally outlying cavities in the neighbourhood of the external orange- coloured cells, as shown in fig. 89. Enclosing the whole is a layer of larger-sized cells, of a dark brown colour, and more angular in outline than any of the othe
. "On the structure, the occurrence in Lancashire, and the source of origin of Naias graminea, Del., var. Delilei, ;. Botany. ON NAIAS DEL., VAR. DELILEI MAGNUS. 28 in the stem, but much smaller and more circular (see fig. 89). These cavities are regularly arranged in one series round the central mass, as in the stem, but there are occasionally outlying cavities in the neighbourhood of the external orange- coloured cells, as shown in fig. 89. Enclosing the whole is a layer of larger-sized cells, of a dark brown colour, and more angular in outline than any of the other cells. In the midst of these cells, but on the outermost side, are a few cells filled with a rich tawny brown pigment. The walls of the circumferential cells are all very thin, and they have the rich colour of the pigment cells. In addition to the roots proper the plant gives off adventitious roots from the stem-nodes, as re- presented in Plate 249. These Fia. 89. are generally given off singly from between the first pair of leaves of the fascicle; occasionally two proceed from the same node, but in such case the second root emerges on the opposite side of the node. In the lower portions of the stem the adventitious roots become more numerous from each node, and they begin to acquire the orange colour of the roots proper. They attain a length of from half an inch to six inches or more, and they have a similar internal structure to that of the roots proper ; the peripheral cells, however, do not possess the angular character nor the tawny colour of the outer layer in the lower roots. The tissue is more loosely aggregated; the intra-cellular cavities are fewer in number and smaller, scarcely exceeding the size of the cells which surround them. The central cavity is present, as well as the surrounding sheath, but the cells of the latter are fewer than they are in the root proper. The external cells do not differ much from the inner cells either in shape or in colour, the rich pi
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Keywords: ., bookcentury1800, bookpublisherlondon, booksubjectbotany, bookyear
