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1904 | WYLIE: ELODEA CANADENSIS ¥7 
- the endosperm nucleus (figs. 35, 36). Inall instances but one 
the male nuclei seen in the embryo sac were in resting condition. 
THE EMBRYO. 
The oospore divides by a transverse wall. The upper nucleus 
retreats toward the micropyle and becomes the center of the 
vesicular cell, which later becomes enormously enlarged. The 
endosperm nucleus does not divide until a two-celled embryo is 
established. In many cases the oospore was found dividing with 
the endosperm nucleus still in resting condition (fig. 76); in 
other instances the endosperm nucleus was in mitosis, but the 
egg fully divided (fig. 77). Figures were never seen in both at 
the same time. Such a tardy division of the endosperm nucleus 
seems very rare. Guignard (7) has figured for Matas major the 
primary endosperm nucleus in the spirem stage by the side of a 
two-celled embryo. Hall (10) also finds in Lzmnocharis emargt- 
nata two nuclei in the young embryo before “the upper polar, 
‘ which forms the endosperm, has gone through the first division.” 
A proembryo of four or five cells is established before the end 
cell divides by a vertical wall (fig. 79). While the development 
of the embryo was not studied in detail, certain variations were 
noted in these earlier divisions. The basal cell becomes very 
prominent. When the parts of the embryo are established, this 
cell has a volume fully forty times that shown in fg. 82, and when 
the seed is nearly ripe it still shows prominently, though somewhat 
flattened, at the root end of the embryo (fg. 83). The remain- 
ing synergid also often enlarges for a time nearly as rapidly as 
the suspensor cell ( fig. 87), and seems during the early stages to 
share with it a common function. 
The embryo seems to be of the usual monocotyledonous type. 
The primary root probably does not function, and secondary 
roots are seen in the seed pushing out near the base of the stem 
(fig. 83). 
SUMMARY. 
1. the pistillate flower is strongly epigynous, and develops a 
long floral tube reaching from the sessile ovary to the surface of 
the water. 
