CFCADEM, 
(as in the sporangia of Lycopodiaceae, Equisetaceae, and Ophioglossaceae) into an 
outer layer of smaller cells enclosing a larger-celled tissue; the cells of the latter 
continue to grow and divide in all directions, and the mother-cells of the pollen 
are finally isolated, but densely crowded together, as in Dicotyledons. The mode 
of division of the mother-cells is nevertheless more like that of Monocotyledons in 
this respect, that they first of all divide into two daughter-cells, each of which 
again undergoes bipartition. The first division-wall is partially formed, as in Dico- 
tyledons, by the slow growth of an annular ridge of cellulose, formed in the depres- 
FlG. 344.— Zt? iiiuricata (after Karsten). A a male flower (natural size) ; B transverse section of one ; C one 
of its stamens with the pollen-sacs x and the peltate expansion s (seen from below) ; D the upper part of a female 
flower (natural size) ; E transverse section of one, j the peltate scale bearing the ovules s k ; F longitudinal section of 
a ripe seed ; e endosperm, c cotyledons, x the folded suspensor. 
sion produced by the previous constriction of the protoplasm of the mother-cell ; 
but in each of the two daughter-cells the second partition appears to be formed 
simultaneously, as in Monocotyledons. The four young pollen-cells are now freed 
by the rapid absorption of the cell-wall which surrounds and separates them. The 
pollen-grains, when free from their mother-cells, are unicellular and spherical ; but, 
during their further growth, the contents, enclosed by an extine and intine, divide 
into two cells, a smaller and a larger one, each possessing a nucleus. The smaller 
of these two cells, lying on one side against the intine of the pollen-grain, becomes 
arched on the opposite side, and projects in the form of a papilla into the larger 
