466 
VASCULAR CRYPTOGAMS. 
Hegelmaier and Russow have confirmed and extended the observation. They are 
developed from a small group of epidermal cells, as Goebel has shown, and, in con- 
sequence of repeated divisions, they soon appear as flat projections occupying the 
whole breadth of the base of the leaf, consisting of a group of internal cells covered 
by an external layer. Tangential divisions take place in the epidermal cells by means 
of which the wall becomes two-layered, and the upper or external portion of the 
tapetum is formed, the tapetum being completed by similar divisions taking place in 
Fig. 327.— a dichotomously branched fertile shoot of Lycopodittfn Chamacyparissus, in longitudinal section, slightly magnified; 
//"the axial fibrovascular mass, hb leaves, ss the young sporangia. 
more deeply placed cells : the archesporium probably consists of a transverse row of 
cells; these undergo division and form a rounded mass of spore-mother- cells. 
These cells become isolated, their walls undergo considerable thickening, and, after an 
indicated division into two they form four chambers (the so-called * special mother- 
cells within each of which the contained protoplasm surrounds itself with a 
permanent spore-wall. It is not until the projections, spines, &c., have been 
developed upon this wall that the walls of the chambers of the mother-cells are 
absorbed. 
