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EMBRYOGENY 13 
Instances like the following strengthen such an idea. In a cluster 
of plants in the greenhouse one pistillate and twelve staminate 
clusters were mature at the same time. Examination of these at 
midday showed 25 living insects in the pistillate spathe and no 
living insects in any of the others. This is an extreme case, to be 
sure, but it is not unique. 
To summarize the case briefly: It is certain. that pollen is 
carried by insects which seek the spathe, probably for shelter or 
hiding. The slight space around the pistillate spike insures the 
transfer of pollen from insect to stigma. There is evidence of 
insects being attracted to the pistillate flower cluster; but outside 
of the possible use of the stigma for food or a possible odor from 
the slime filling the ovary cavity, the cause of such attraction is 
unknown. 
EMBRYOGENY 
The only published account of the embryogeny of Arisaema 
triphyllum is that by Gow in 1908 (13). The findings of that 
paper, briefly stated, are as follows: The fertilized egg does not 
divide until after the endosperm development has begun. The 
first two divisions are transverse followed by a longitudinal division 
(13, f. 20-22). The figures show a regular chain of two and of 
three cells, without showing their relation to the basal cell cut off 
by the true first division. : 
The following notes are based on the study of more than two 
hundred preparations covering the phases of development de- 
scribed. 
At the time of entrance of the male nucleus, the egg nucleus is 
well defined and about the size of the synergid nuclei. After 
fertilization the egg nucleus increases in size so that at the time 
of segmentation for the first division it has reached about twice 
its former diameter. This resting stage, if it may be so designated, 
is about twenty-four hours in length. As reported by Gow (13, 
p- 42) the fertilized egg does not divide until after the endosperm 
has well started (PLATE I, FIG. 9; PLATE 2, FIG. 30). In fact the 
perm mass may be composed of twenty cells before the first 
division occurs. Ovules fixed 86 hours after pollination show em- 
bryos of two to six cells, and endosperm of twenty to forty cells. 
Those fixed 72 hours after pollination show eggs ready for the first 
