30 CoMPARATIVE EMBRYOLOGY OF THE RUBIACEAE 
cut off, and numerous starch grains may then be seen. The long 
antipodal which occupies about three-fourths of the length of the 
entire embryo-sac takes on a definite club shape at its free ex- 
tremity which reaches quite to the end of the megaspore cavity, 
and is finely granular, though not so densely filled with protoplasm 
as are the others. A large vacuole appears constantly at the thick 
end which abuts against the small antipodals. The vacuole ex- 
_tends as far as the nucleus. The interior of the narrow upper 
part is also occupied by a vacuole, though this is less evident in 
sections on account of the slender character of this region of the 
cell. A normal appearance is presented by this cell as by the 
other two until the proembryo has reached an eight- or.ten-celled 
stage or even older (p/. 6, fig. 5), and an application of the iodine 
test demonstrates that at such a time the small antipodals are 
gorged with starch while the other shows a similar starch content 
at its thick end. The haustorial end stains deep yellow and is 
free from starch. No trace of the deeply staining products of dis- 
integrated megaspores may be seen after the second or third divi- 
sion of the endosperm nuclei, though this is, of course, a somewhat 
variable matter. Disintegration of the antipodals sets in with the 
rapid extension of the endosperm, and they are finally lost to view. 
ENDOSPERM AND INTEGUMENT 
Soon after fertilization the endosperm nucleus divides. This 
division is followed by several, others, probably five or six, before 
any walls are laid down. Its starch content is drawn upon during 
these divisions, so that at the time the cell walls are laid down, ` 
only a very little may be found or none at all. The proembryo 
remains unicellular till about the third or fourth division of the 
endosperm nuclei occurs. The growth of the endosperm is ac- 
companied by destruction of the integument. The peripheral endo- 
sperm cells become less vacuolated, the greatest density of con- 
tents being found in those cells of the endosperm which lie towards 
the raphe, 7. ^, the peripheral cells are most active where the 
largest amount of food is available. The accumulation of starch 
is gradual at first and is localized in the chalazal end of the endo- 
sperm. Later all the cells become gorged with starch, so that at 
the time the cotyledons appear, all the cells are well supplied with 
