776 Campbell\—The Embryo-sac of Pandanus . 
As the ovule develops there is relatively little increase in the size of 
the nucellus, which becomes replaced by the enlarging embryo-sac, but the 
funiculus and the part of the outer integument adjoining it become much 
enlarged, so that the ovule has quite a different form from the earlier stages. 
This recalls the ovules of many Araceae, where there is a similar enlarge¬ 
ment of the basal region of the ovule. Traversing the funiculus there is 
a single fibro-vascular bundle. 
P. affinis differs slightly from the other species examined in the form 
of the embryo-sac mother-cell, as well as in the greater thickness of the 
apical tissue of the nucellus. As the older stages of this species were not 
available it is impossible to say how these would compare with corre¬ 
sponding stages in the other species that were studied. The embryo-sac 
mother-cell (Fig. 3, PI. LIX) was undivided, but it could be easily recog¬ 
nized by its dense contents and its very conspicuous nucleus. In section it 
appears almost triangular in form, with pointed base and broad apex. Above 
it there lies a group of cells, probably tapetal or parietal cells, which to 
judge from their position are the product of the repeated division of 
a primary tapetal cell. 
The Pollen. 
Only a very casual study of the pollen was made. The apparently 
ripe pollen-spores from an undetermined species (Fig. 2) were found to 
have a small cell (in) cut off from the body of the spore. The nucleus 
of this small cell was much smaller than that of the body of the spore. It 
is probable that the small cell is the antheridial or generative cell, and that 
its nucleus later divides into two. There is a possibility, however, that it 
represents the small sterile or prothallial cell which occurs in Spar gallium 
simplex , and that the large nucleus divides again to form the generative 
and tube nuclei. 
The Embryo-sac of Pandanus Artocarpus. 
The earlier stages of the embryo-sac found in P. Artocarpus 
(Figs. 4-6) were somewhat more advanced than that described in P. affinis. 
The mother-cell is more nearly cylindrical and the base is truncate, and 
sometimes almost as broad as the apex, and in such cases it is the lower¬ 
most of a single series of cells, or at least such is the appearance in longi¬ 
tudinal section (Fig. 6). More commonly the upper end of the mother-cell 
is rather broader, and there are two series of parietal cells to be seen in 
longitudinal section (Fig. 5). There are two other layers of these parietal 
cells between the young embryo-sac and the epidermis at the apex of the 
nucellus. The sporogenous cell divides transversely into two, one of which, 
the lower, is the larger and becomes the embryo-sac (e. s.)- The upper cell 
(x) divides into two by a vertical wall, and these two small cells persist with 
