646 MINNESOTA BOTANICAL STUDIES. 
present paper were made from sections stained with aniline- 
water-safranin or acid fuchsin. 
At the present time the material at hand is insufficient for the 
full demonstration of certain points, especially in the develop- 
ment of the embryo-sac. Therefore, the present paper will be 
limited to a discussion of the embryogeny, the development of 
the embryo-sac and the cytology of reproduction being reserved 
for future treatment. 
RESEARCH. 
The embryo-sac is ovoid at its micropylar end and tapers down 
to a narrow attenuation which extends deeply into the nucellus. 
As the embryo-sac matures the nucellar tissue directly in con- 
tact with it begins to break down. There also appears in 
the antipodal region a club-shaped cellular structure which 
obliterates the lower portion of the sac (Figs. 1 and 2). The 
precise origin of this peculiar antipodal body remains yet to be 
determined. To facilitate description the embryogeny may be 
considered in a series of stages. 
Stage A. Spherical stage.—The young embryo is usually 
found in the upper end of the embryo-sac among the débris re- 
sulting from the disintegration of the synergide. The sur- 
rounding protoplasm makes it difficult to observe the first 
division of the odsperm and at the present time the youngest 
embryo which can be described with certainty is one in the 
eight-celled stage represented in Fig. 3. Asseen here the embryo 
is nearly spherical, no suspensor being evident, although there 
may be one present but obscured by the disorganizing synergid 
‘©a.” This is not probable, however, judging from the position 
of the first wall in the segmenting embryo. If a suspensor cell 
is cut off at all, it very early loses its identity as there is no 
evidence of it in embryos of the age represented in Figs. 
4-6. Cell division apparently takes place uniformly through- 
out the embryo, the result being the building up of a spherical 
body (Figs. 4-7). The embryo retains its spherical shape until 
composed of several hundred cells. At about this time the 
nucellar tissue in the micropylar end of the ovule has entirely 
broken down, so that the embryo now lies in a cavity which is 
bounded by the inner integument of the ovule. Simultaneously 
with the division of the embryonal cell the endosperm nucleus 
divides and the young embryo is soon surrounded by endosperm 
