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1904] BILLINGS—TILLANDSIA USN EOIDES 103 
The first division of the archesporial cell is usually followed by 
a transverse wall and a resting condition of the nuclei (jig. 5); but a 
single case was observed, as reported by Smiru (3) for Hichhornia 
crassipes, in which a row of four nuclei was formed without sepa- 
rating walls (fig. 7). In Eichhornia the absence of the walls is said 
to be the rule, but in Tillandsia it is the exception. The division 
which gives rise to the third and fourth megaspores, thus completing 
the axial row, will be seen from fig. 6 to be in the cell nearest the 
micropyle. In the meantime, the basal of the two proximal mega- 
spores begins to elongate, and is destined to develop into the embryo 
sac. - A vacuole is formed in this cell as it pushes outwards crushing 
the other three megaspores, whose contents soon show evidence of 
breaking down. The remaining stages in development are the 
familiar ones of complete absorption of the non-functional mega- 
spores by the functional, and the internal division of the latter into 
eight cells. The two cells that are to form the synergids soon come 
to possess larger nuclei than does the egg cell. The egg nucleus 
in fact is smaller than is customarily observed. In the completed 
embryo sac, the egg often lies against the wall of the sac near one 
synergid, but may occupy a position between the synergids. The 
polar nuclei usually approach each other and fuse near the antipodal 
region (fig. 14). The antipodals occupy a pocket at the extreme 
end of the sac. 
FERTILIZATION. 
The pollen tube passes through the micropyle, penetrates the 
nucellus, and enlarges as it enters the embryo sac. It does not 
appear to pass between the synergids, but to one side of them, one 
synergid being disorganized in the process. The two male nuclei 
which have arisen from the generative nucleus during the develop- 
ment of the pollen tube lie near together and a little in advance of the 
tube nucleus. In no case observed did the male nuclei show the 
much elongated, spermatozoid-like form so often described for other 
plants. In fig. 15, which represents the tube before its rupture, 
they are elliptical; but when discharged they are slightly more elon- 
gated and may have pointed ends. The place of discharge may be 
cither at the end of the tube or lateral, though near the end (figs. 
16-19). The tube nucleus is usually to be seen at the time of dis- 
