400 CHURCH: DEVELOPMENT OF EMBRYO SAC AND EMBRYO 
thronium (Schaffner, 11), Lilium and Tulipa Gesneriana (Treub 
and Mellink, 12) and other Liliaceae, we may for the present assume 
that the reduction division occurs with the division of the one-celled 
stage and is completed when the four-nucleate embryo sac is 
formed (Fics. 4, 5). By a division of the four ails the eight- 
nucleate sac results (Fic. 6). 
At the time of fertilization the two polar nuclei are in the 
chalazal half of the sac, the antipodals near the chalaza, and the 
egg cell and the synergids opposite the micropyle (Fic. 6). The 
polar nuclei have a very thin protoplasmic content, although their 
nucleoli stain heavily. The three antipodals are at first arranged 
in a pyramid whose apex points toward the micropyle. Just 
before fertilization they become rearranged in a row, parallel 
with the longitudinal axis of the chalazal end of the embryo sac; 
while after fertilization they generally move again, this time to 
form a pyramid with its apex directed toward the chalaza. The 
antipodals stained very deeply in all of the combinations of stains 
that were used. This may be indicative of disintegration. The 
synergids have dense but vacuolated protoplasm. The egg cell 
is large and pear-shaped with a large round nucleus. It is 
directly in front of the micropyle. The dense protoplasm of the 
egg is less vacuolated than that of the synergids. 
The nucellus at the time of fertilization has been largely 
absorbed or digested except for a thin layer of cells about the 
micropylar portion of the sac and a small mass of cells located at 
the chalaza and almost wholly deprived of protoplasm. The 
antipodals show a marked tendency to enlarge, and in numerous 
instances increase so as to almost equal the egg cell in size. This 
tendency toward enlargement persists even after fertilization, when 
the partial development of the embryo has taken place. Ordi- 
narily, however, the antipodals have almost disintegrated when 
the embryo has become two-celled. The two polar nuclei, which 
are in close contact at maturation, fuse at the time of fertilization. 
A few examples of triple fusion were observed (Fic. 8). Ernst 
(2) has observed this condition in Paris quadrifolia. Further, 
it has been observed in other Liliaceae: asin TriJlium grandtf olium; 
in species of Liliwm, of Fritillaria, and of Tulipa; and in Endymion 
nutans (Coulter and Chamberlain, 1). The synergids disappeat 
at fertilization. fei, 
