I9 i S ] PETRY—OPHIOGLOSSACEAE 361 



through the winter, and only dies in the early summer of the eighth 

 year, after the emergence of the next younger leaf. 



The bud.— As stated above, the first evidence of the formation 

 of a new leaf is the abrupt rise of the entire segment above the 

 plane of the apex. This growth is relatively slight in amount, and 

 the further development of the young leaf is apical. The cells 

 produced by the apical growth are arranged in such definite rows 

 (fig. 15) that it is easy to distinguish the tissue produced by the 

 apical cell. 



The axillary bud can first be distinguished on the adaxial face 

 of the base of a young leaf, after the apical growth of the leaf has 

 proceeded to a considerable extent .(fig. 15). At this time, it con- 

 sists of a plate of meristematic cells, 6-8 in number; there is no 

 evidence of an apical cell. The arrangement of the surrounding 

 cells shows clearly that the bud has not come from the apical cell 

 of the leaf, but has arisen from cells carried up by the elongation 

 of the segment. By the upgrowth of the apical region of the stem, 

 this plate of meristematic cells is thrown into a crevice, which lies 

 between the stem and the adaxial face of the base of the leaf; 

 fig. 14 shows the appearance of a bud a year older than that shown 

 by fig. 15. It consists of a mass of 30-40 cells, lying as a plate at 

 the base of the leaf; one of the cells shown has divided by a peri- 

 clinal wall, but such a division occurs rarely. 



In older leaves, the location of this crevice or slit is readily 

 pointed out by the margin of the stipular sheath of the next younger 

 leaf; this makes the identification of the buds in longitudinal sec- 

 tions of the rhizome particularly easy. Fig. 16 shows the margin 

 of the stipular sheath of the functioning leaf of a rhizome, and the 

 bud formed in the axil of the leaf of the preceding year; fig. 17 

 shows a bud a year older. They consist of plates of cells of a 

 meristematic nature; these plates are never more than two cells 

 in thickness and are usually 5-8 cells in longitudinal extent. In 

 tangential sections of a rhizome (figs. 18, 19), they are seen to be 

 6-10 cells in width; the canal by which they communicate with the 

 exterior is a mere slit. There is not the slightest evidence of any 

 apical cell, or other indication of an apex. They agree in all 

 essentials with the buds of B. Lunaria as described by Lang. 



