CRYPTOGAMS 



421 



cnib 



The egg-cell is divided by the formation of a transverse wall into two 

 cells ; the upper and larger cell 

 increases considerably in size, 

 and gives rise, by the division of 

 its lower portion, to a suspensor 

 (Fig. 355, et), while the lower 

 epibasal cell, by repeated divi- 

 sion, develops into an embryo, 

 provided with two primary 

 leaves and further segmented 

 into stem, root, and foot (bl, st, 

 w, /). The foot, in this in- 

 stance, has another position and 

 origin than in Lycopodium. Each 

 primary leaf has, even at this 

 stage, a ligule (lig) formed by 

 the outgrowth of the leaf-base. 

 The suspensor is perpen- 

 dicular to the axis of the 

 embryo ; its function is to push 

 the embryo into the tissue of 

 the prothallium, with which 

 the foot, -the organ of absorption, is thus kept in close contact, 



Fia. 354. — Selaginella Martensii. Female prothallium 

 protruding from the apex of the ruptured macro- 

 spore ; spm, wall of macrospore ; ar, an unfer- 

 tilised archegonium ; embi, emb% two embryos, 

 with suspensors et, sunk in the tissue of the pro- 

 thallium. (After Pfeffer, X 124.) 



The 



Fig. 355.— Selaginella Martensii. Longitudinal section of an embryo before its separation from 

 the spore; et, suspensor; w, root;/, foot; bl, leaves; lig, ligules ; st, apex of stem. (After 

 Pfeffer, x 165.) 



stem apex, with, the first pair of leaves, eventually grows upwards, and 

 the root also extends beyond the macrospore. As the foot still 



