468 



MOSSES AND FERNS 



CHAP. 



Their researches, however, showed conclusively that this was 

 not the case, but that the origin is exogenous. In most species 

 they 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. telmatcia they do not occur at all, 

 as a rule, upon the colourless sporiferous shoots, but are regu- 

 larly formed from all but the lowest nodes of the sterile stems. 



Fig. 272. — Longitudinal section of a young vegetative shoot showing two young 

 leaves (L.), X200; B, section passing through the base of a somewhat older leaf; 

 fb, vascular bundle; C, section passing through a young bud (,k). 



In E. scirpoidcs 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 

 median longitudinal sections through a vigorous sterile stem of 

 E. telmatcia or E. arvcnsc before it appears above ground. The 

 young bud (Fig. 272, 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, w^hich 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 



