FILICINEM. 
A51 
macrospore — increases very much in size whilst the other three gradually shrivel. 
Figures 323 and 324 illustrate the development of the macrospore of Pilularia 
globuli/era, after drawings made by me in 1866. They show the young macrospore 
in /, //, ///, still in connexion with its three sister-cells which are invested by the 
cell-wall of the mother-cell which has already become mucilaginous (7). The four 
cells are attached to each other by means of rigid spine-like projections, that of the 
macrospore being the most strongly developed. At a later period the macrospore is 
Fig. 322. — Development of the sporangium of /'z/«/«;'?'.^ FIG. 323. — Development of the macrospore of Pibila7-ia 
globuli/era, all the figures in optical longitudinal section ; glob7ilifera ; x the abortive sister-cells, m the macrospore, Ä'its 
/Kc primary mother-cell of the spores invested by the nucleus, a the inner, * the outer coat, 
tapetum ; sm mother-cells of the spores (X 550). 
of very considerable size ; its aborted sister-cells are attached to it laterally (Fig. 
324, x), and its firm coat has become brown and is invested by a layer of mucilage 
(Fig. 323, IV, b) which often appears to be folded. It forms a papilla (Fig. 324, b') 
at the apex which shrivels when the spore ripens. A layer of a soft substance, 
presenting a distinctly prismatic structure, makes its appearance (Fig. 324, C) on the 
outside of the mucilaginous layer, and becomes in its turn invested by a third layer 
which is thicker than itself of a less distinctly organised structure. Both these layers 
leave the apex of the spore uncovered and form a funnel through which the 
