1913] YORK—DENDROPHTHORA 107 
adjacent to it in the form of pseudopodium-like projections. The 
cells in contact with these pseudopodia were partially digested 
(figs. 34, 43). The nuclei of the long arm of the sac are derived 
from the two micropylar nuclei of the four-nucleate stage, at which 
period in the development of the sac they are usually a short 
distance apart. Preceding their division, which begins about the 
time the sac commences to grow downward, they come together 
and lie in close contact until after they have divided. They are 
so intimately associated that in some examples they appear to be 
partially fused. In the stage preceding the upward growth of the 
tubelike sac, they are found partially divided in a mass near the tip 
of the sac, in which 6 nucleoli are distinguishable, some of which are 
entirely inclosed by a nuclear wall (figs. 35, 36, 38, 39). Examples 
were found where the sac had advanced well up into the carpel and 
in which the nuclei had just begun to divide (fig. 34). Either 5 
or 6 nuclei are formed, and for some time after the divisions are 
complete they lie massed together (figs. 32, 37). About the time 
the tip of the sac has reached to or a little above the level of the 
apex of the axis, the nuclei of the sac separate, 2 occupying the 
position of polar nuclei, the other 3 or 4 forming the egg apparatus 
8S. 41, 42, 43). The two nuclei corresponding to polar nuclei 
of a sac of the usual type are sister nuclei, having resulted from 
the division of one of the two nuclei at the micropylar end of the 
four-nucleate sac. From the sister nucleus of this same nucleus 
the nuclei of the egg apparatus are derived. There are 7 or 8 
nuclei formed in each sac. If we try to homologize them with the 
nuclei of a sac of the usual type, we find 2 or 3 cells having the 
position of synergids accompanying the egg nucleus at the micro- 
pylar end of the sac, the 2 just below the egg have the position of 
polar nuclei, and the 2 in the chalazal region correspond to antipo- 
dals. While the long arm of the sac has been developing, the 
chalazal end has been enlarging and slowly advancing toward the 
apex of the placenta where it meets the chalazal arm of the sister 
sac (text fig. 20). At first they are separated by a thin wall, which 
finally disappears during the early stages of the formation of the 
embryo, so that the two sacs form one continuous tube (fig. 30). 
The embryo sac of Dendrophthora as thus seen is quite different 
