344 Campbell— Studies on the Araceae , ///. 
antipodals, as in Fig. 51, the denser basal cells of the endosperm probably 
are derived entirely from the divisions of the lower of the two primary 
cells. 
Comparing Nephthytis with the other Araceae that have been studied, 
it is evident that it most nearly resembles Aglaonema , especially A. 
commutatum 1 . The inflorescence and individual flowers are very similar 
in the two, and the form of the ovule almost identical. There is the same 
great variability in the development of the embryo-sac, and the variations 
are of much the same nature, including the variable number of young 
embryo-sacs, the position and general structure of the embryo, multiple 
nuclear fusions, imperfectly marked polarity, and the variable character of 
egg-apparatus, antipodal cells, and endosperm nuclei. 
General Conclusions. 
The Araceae, although evidently all more or less intimately related, 
show a good deal of difference in the floral structures. The simplest type 
of flower is that where the flowers are unisexual, the pistillate flower 
having a single carpel, with a solitary basal ovule. Spathicarpa , Aglaonema , 
and Nephthytis are examples of this type. In the more specialized forms 
there are two or more carpels which may each develop several ovules, as in 
Philodendron and Anthurium. While in some of these, e. g. Arisaema y 
the basal origin of the ovules is apparent, in others, like Anthurium , this 
is not the case. The latter genus represents perhaps the most specialized 
type of flower, as there is a truly compound pistil and the flowers are 
hermaphrodite. Moreover there is a rudimentary perianth. 
Engler 2 considers the type of flower found in the Pothoideae, to which 
Anthurium belongs, as the more primitive, the simpler flowers of the 
genera being reductions from this type. In view of the strong probability 
that the unisexual flowers, in, general, are more primitive than hermaphro- 
dite ones, and that in the Araceae most of those (e. g. Aglaonema , 
Nephthytis ) which seem to have the most primitive form of embryo-sac 
are unisexual, it seems more likely, in the writers opinion, that the latter 
are primitive forms, rather than reduced ones. We incline to the belief that 
the flower of Spathicarpa , for example, a single carpel with the solitary 
basal upright ovule, comes very near the primitive type from which the 
others have been derived. 
In studying the development of the archesporium it has been shown 
that although there may be a single embryo-sac mother-cell, there is not 
infrequently a group of sporogenous cells, and that more than one embryo- 
sac may begin to develop. Examples of this are Arisaema , Aglaonema , 
and Nephthytis , and it is probable that the same condition will be found to 
1 Campbell, loc. cit, II. 2 Loc. cit., p. 119. 
