Campbell. — Studies on the Araceae. 669 
large solitary anatropous basal ovule. The nearly globular 
ovary is crowned with a large discoid sessile stigma, slightly 
depressed in the centre, where it joins the very short canal 
leading to the ovarian cavity. 
While A. commutatum and A. pictum agree closely in their 
structure, the former, owing to its larger nuclei, as well as 
from the peculiarities of the embryo-sac, was especially studied, 
and, unless otherwise stated, the account here 'given refers to 
this species. 
The ovule from the first is very massive, and while the integu- 
ments are developed at an early period, they remain short, 
the chalazal region of the ovule being very large — a not 
uncommon feature in other Araceae as well. The short 
funiculus is also very thick. 
The nucellus is relatively small. In the youngest stage 
observed (PI. XXX, Fig. 1) the young embryo-sac was already 
evident, an elongated cell with a large nucleus. Whether in 
this case the embryo-sac arose directly from a hypodermal 
cell, or whether it was the product of the division of a primary 
archesporial cell, could not be positively ascertained. 
The lateral tissue of the young nucellus consists of two of 
three layers of cells, while at the summit the cells are some- 
what larger, and persist as a cap of tissue after the lateral 
tissue of the nucellus is destroyed. This occurs at an early 
stage, so that the embryo-sac soon comes into contact with 
the inner integument. 
In a number of cases observed, and this evidently is not 
unusual, the archesporium consisted of two or three large 
cells, all of which were apparently potential embryo-sacs. 
These ovules (Figs. 5, 7) much resemble those of Arisaema 
triphyllum. 
As the embryo-sac enlarges the lateral tissue of the nucellus 
is soon crowded upon, and finally becomes quite obliterated. 
The apex of the nucellus, as in many other similar cases, 
persists as a conical cap above the apex of the embryo-sac. 
There is so much variation in the behaviour of the embryo- 
sac in its earlier stages that it is difficult to say what may be 
