430 SHaw: NOTE ON THE PAPAVERACEAE 
spores are being formed from their mother-cells. No trace of the 
megaspore mother-cell is visible when growth is renewed in late 
winter. Sanguinaria is therefore in this respect like Sa/zr and 
Populus, whereas certain other plants, most definitely Epigaea and 
Erythronium, have been observed to reach the mother-cell stage 
during the preceding season. 
The division of the megaspore mother-cells and the formation 
of the embryo-sac take place during March and early April. Al- 
though the development of the microspores has kept far in advance, 
the flower at blooming is proterogynous. As is well known, the 
phases from pollination to maturity of seeds occur in April, May 
and June. 
Structure of the pistil—In Sanguinaria, Chelidonium and Esch- 
scholtzia, an open canal leads from the ovary to the exterior. 
Hairy outgrowths of a kind with those of the stigma project into 
the passage but generally do not close it, and continue down the 
two placental ridges. Thus the hairy outgrowths of the stigma, 
of the interior of the stylar canal and of the placental ridges form 
a single continuous tract. This is highly developed in Sanguin- 
aria, less so in Chelidonium and Eschscholtzia, but distinctly in all. 
The path of the pollen-tubes is among these hairs and the loose 
superficial cell-layers from which they spring. The tubes pass 
through the micropyle and penetrate the nucellus in the usual 
manner. 
The embryo-sac.—The embryo-sac exhibits the typical number 
and arrangement of nuclei (PLATE 15, FIGURES I AND 2). The polar 
nuclei are often met with, lying close together. In the antipodal 
region are found features of interest. The antipodal cells reach 
an unusual size, and the nucellar cells in their vicinity acquire 
thickened walls. In Zschscholtzia the antipodals continue to en- 
large for a brief period during the early formation of the endosperm 
nuclei and then decrease and disappear before the endosperm cells 
are cut out. 
In Chelidonium (PLATE 15, FIGURE 2), the antipodals are rela- 
tively smaller than in Eschkscholtzia but they persist longer and may 
be seen after walls have formed about the endosperm cells. For 
Sanguinaria also the statements in regard to Chelidonium hold true. 
In all three forms the cells in the nucellus adjacent to the anti- 
