446 



MOSSES AND FERNS 



CHAP. 



not the case, but that the origin was exogenous. In most 

 species these are produced abundantly, and a bud is formed in 

 the axil of each leaf, although it frequently happens that some 

 of them do not develop fully. In E. telinateia they do not 

 form at all, as a rule, upon the colourless sporiferous shoots, 

 but are regularly formed from all but the lowest nodes of the 

 sterile stems. In E. scirpoides they are absent from all the 

 aerial stems, but whether rudiments of them are formed does 

 not seem to have been investigated. 



Their development may be readily traced in a series of 



Fig. 233. — Longitudinal section of a young vegetative shoot, showing two young leaves (L.), X200; 

 B, section passing through the base of a somewhat older leaf ; /i, vascular bundle ; C, section 

 passing through a j'oung bud {k). 



median longitudinal sections through a vigorous sterile stem of 

 E. telinateia or E. ai'vense before it appears above ground. 

 The young bud (Fig. 233, C) originates from a single epidermal 

 cell just above the insertion of the leaf This cell enlarges 

 and is easily recognisable. In it are formed three intersecting 

 walls cutting out the apical cell, which at first is somewhat 

 irregular, but soon assumes its definite form, and the subsequent 

 growth of the branch resembles in all essential points that of 

 the main shoot. Very early the cells of the leaf-base immedi- 

 ately above the young bud grow around it like a sheath, and 



