XIV 



L 1 'COPODINEJC 



493 



The primary root, as in Lycopodiiuii, forms late, and no trace 

 of it can be seen until the other parts are evident. It arises in 

 the larger leaf-segment, close to the suspensor, and therefore is 

 separated from the cotyledon by the foot. The root-cap arises 

 from a superficial cell, which divides early by both periclinal 

 and anticlinal walls, and thus becomes two-layered. h'rom a 

 cell immediately below is derived the single apical cell to 

 which the subsequent growth of the root is due. The further 

 divisions in the primary root were not followed. 



The axes of the stem and root soon develop a strand of 

 procambium which is con- 

 tinuous in the two, but to 

 judge from Pfeffer's figures, 

 the cotyledons do not de- 

 velop their vascular bundles 

 until later. The early 

 growth in length of the 

 root is mainly intercalary, 

 as the divisions in the 

 apical cell for some time 

 are not very rapid, and for 

 a long time the root-cap 

 consists only of the two 

 original layers. 



With the growth of the 

 embryo the cell -formation 

 in the lower part of the 

 spore continues until it is 

 filled with a continuous 

 large-celled tissue, the con- 

 tents of whose cells are 



much less granular than the undivided regions of the spore, and 

 as the embryo develops the foot crowds more and more upon 

 them until it nearly fills the spore-cavit}'. 



On comparing Pfeffer's account of 5. Martcusii w ith ni\- 

 own observations upon wS. Kraiissia7ia, the main differences 

 consist first in the smaller development in the latter of the 

 primary prothallium, i.e. the prothallial tissue formed before 

 the spores are shed, the archegonia being only separated from 

 the diaphragm by a single layer of cells instead of by three or 

 four, as in 5. Martensii. L. apus, which was also examined by 



Fig. 258. — Longitudinal section of a fully-developed 

 prothallium of JT. Kraitssiaiia, with an advanced 

 embryo (4V«), X77 ; /, ligula. 



