1913] GOW—MORPHOLOGY OF AROIDS 129 
indicates that the divisions are simultaneous. The separation of 
the two male nuclei follows immediately on the liberation of the 
pollen grain in the loculus. 
The compound ovary consists sometimes of two but usually of 
three closely united carpels, with a single truncate style whose 
canal is filled with viscid conducting tissue. Each of the three 
carpellary cavities contains two laterally attached anatropous 
ovules (fig. 5). The immature ovules are at first erect, but soon 
become reversed through the non-development of their lower 
surfaces. Simultaneously with their reversal, the primary arche- 
sporial cell becomes differentiated, and can readily be detected 
by its heavy chromatin network and ready reaction to hematoxylin 
stain (fig. 6). Two divisions occur, giving rise directly to 4 mega- 
spores (fig. 7), the lower 3 of which are suppressed and break 
down. The functioning megaspore increases rapidly in size. 
The nuclear divisions are of the usual type, resulting in the for- 
mation of 8 cells. Egg, synergids, and antipodals are well marked 
by their positions (fig. 8). After fertilization the endosperm 
develops rapidly, and soon fills the embryo sac with a mass of 
, heavy-walled tissue (fig. 9), after which the division of the 
fertilized egg produces the usual form of proembryo (fig. 10). 
The ultimate fate of the endosperm in this species is not known. 
4. Philodendron Wendlandii 
The staminate flowers crowd the upper part of the slender 
spadix and consist each of a single, 4-loculate stamen without 
floral envelopes. Dehiscence is along longitudinal grooves. The 
divisions of the mother cells are simultaneous, producing the usual 
type of tetrad. The tapetum is rather thin (3-4 layers of cells) 
and breaks down early, the nuclei sometimes floating free for a 
time before complete disintegration takes place. 
Nine carpels are arranged radially around a common axis, form- 
ing a single compound pistil. Each carpel contains two slender 
pseudo-anatropous ovules. It is probably correct in this case to 
regard the placenta as the suppressed floral axis and the ovules 
as lateral shoots (fig. 11). The thin integuments project far over 
the tip of the nucellus, the lateral portion of which becomes sup- 
