1913] GOW—MORPHOLOGY OF AROIDS 131 
pressed through the pressure of the growing embryo sac. The 
latter is 8-celled, the arrangement being of the usual type (fig. 12). 
The endosperm is heavy-walled as in Anthurium, and the 
proembryo is egg-shaped. 
5. Philodendron gloriosum 
The ovule is much like that of the species just described. 
Like it the embryo sac is 8-celled, the endosperm is heavy-walled, 
and the embryo spherical to ovate. 
6. Arum maculatum 
This plant was obtained from a local florist and grown in pots. 
Owing to difficulty in the fixation of material the earlier phases 
cannot be given. It has the usual 8-celled embryo sac and spherical 
proembryo, and a thin-walled endosperm which is persistent in the 
seed. 
7. Xanthosoma sp. 
Through accident the label attached to this specimen was lost 
in transit. As the material was cut into cubes and in the fixing 
medium its identity could not be traced. 
Each cell of the tricarpellate ovary contains two slender anat- 
ropous ovules. A series of long conducting cells lines the interior 
of each carpel and extends to the micropylar extremity of the ovule. 
The extremity of the truncate style is covered with glandular 
papillae. The ovule is extremely slender, as in Philodendron, but 
is sessile and does not occupy the reversed position. There appear 
to be 5 antipodals (fig. 13), the other contents of the embryo sac 
being what might be anticipated in any angiosperm (figs. 14-17). 
Many of the cells surrounding the embryo sac were found to 
be in an active state of division, probably owing to the increase 
necessitated in the accessory tissue by the enlargement of the 
embryo sac. This gave a good opportunity to study the phases 
of homotypic division. No continuous spirem stage could be 
discovered. The chromatin reticulum is at first very fine, the 
strands later shortening and thickening, and finally breaking 
into an irregular mass of coarse threads which soon resolve them- 
selves definitely into 16 chromosomes. Early splitting of the 
chromosomes was noticed in a few cases (figs. 18-24). 
