6 Campbell.—Studies on the Araceae. 
downward are the young anthers (Fig. i6 sp.). Each anther 
develops two loculi. 
Owing to the uniformity in size and contents of the cells 
composing the young stamens, it is not possible to determine 
with certainty the exact origin of the sporogenous cells. The 
shaded cells in the figure (Fig. 17) probably represent the 
beginning of the archesporial tissue, but it is quite possible 
that some of the surrounding cells may also contribute to this. 
Outside of the sporogenous tissue there are about four layers 
of cells which form the wall of the anther. 
The further history of the anther was not followed in detail. 
The young pollen-spores, which are of the bilateral type, are 
oval in form (Fig. 18) and surrounded by a firm membrane. 
The cytoplasm fills the cell, and the nucleus is almost central 
in position. The young spores are embedded in a thick layer 
of nucleated protoplasm, doubtless derived from the broken- 
down tapetum, and perhaps in part from a portion of the 
sporogenous cells. This point was not, however, investigated. 
As the spores ripen they increase a good deal in bulk and 
become almost globular in shape. Vacuoles appear in the 
cytoplasm, and the nucleus divides into two—a large vegetative, 
and a smaller generative nucleus, the latter enclosed in a 
small lenticular cell (Fig. 19). No cases were seen where the 
generative nucleus had divided, and this final division does not 
probably occur until after the germination of the pollen-spore, 
which I had no opportunity of studying. 
The Ovule. 
The ovule, as we have seen, is an axial structure, and not 
an outgrowth of the carpel. In the earliest stage seen (Fig. 
4), the ovule is nearly straight with a massive base and the 
beginning of the first integument. The nucellus is nearly 
hemispherical in form, and the single hypodermal archesporial 
cell is already evident. Very soon the second integument 
makes its appearance below the first one, which reaches 
nearly to the apex of the nucellus ; the latter has also elon¬ 
gated. The accelerated growth of the cells on the upper side 
