( 340 ) 
served. The endosperm is only a very thin peripheral mass, 
at the time in the development of the embryo indicated by 
figure 27. Its nuclei are very small and are not clearly dis- 
tinct, but are thickly scattered through a densely granular 
protoplasm. The cavity occupied by the embryo-sac rapidly 
expands after fertilization and the endosperm remains closely 
applied to its periphery. At the micropylar end the cavity 
is oval, narrowing quickly to a narrow tube which stretches 
toward the chalaza, the tissue of the nucellus disintegrating 
before it. 
Melothria 
The ovule originates in Melothrza as a rounded elevation 
on the right or left flank of the placenta. By growth of the 
hypodermal cells at the apex of this elevation, its cells are 
brought into a serial arrangement in rows running back 
toward the base of the rudimentary nucellus. The spore- 
mother-cell apparently originates in this form as in Fevdllea. 
The earliest stage observed is represented by figure 25, which 
shows the relative size of the spore-mother-cell and its rela- 
tion to other parts of the young ovule. While the subse- 
quent stages of devel t were not fully represented in the 
preparations ohiatned, a: was observed to give a more 
or less adequate idea of the course of development. 
About the time when the spore-mother-cell appears, the 
ovule begins to turn toward the placenta and the inner integ- 
uments begin to show. At this time the apex of the nucellus 
is directed toward the center of the ovary, thus having its 
long axis coincident with a radius. When the embryo-sac 
has reached the four-celled stage as shown in figure 26, it 
has turned to a position at right angles to a radius. Numer- 
ous preparations showing four cells in the embryo-sac were 
obtained, but in none of these was there any evidence of 
degenerated potential megaspores. If such structures were 
present they must have disappeared early. By the time the 
embryo-sac has become ready for fertilization the micropyle 
is directed outward. The embryo-sac in all stages in Aelo- 
thria is very minute and does not lend itself to the study of 
