June, 1904 .] The Embryo-sac and Embryo of Nelumbo. 
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approaching each other, the lower polar nucleus travels much 
farther than the upper one and the fusion usually occurs near 
the egg or even in contact with it (Fig. 13). Quite a number of 
examples of a triple fusion were found. In many of the prep- 
arations in which the pollen tube had appeared, two of the nuclei 
were about the same size while the third one was smaller (Fig. 
14). Several other examples were found where there were three 
conjugating nuclei, almost equal in size and similar in appearance 
even before the pollen tube had appeared. It seems that in the 
first instance where fertilization had occurred, the small nucleus 
of the three conjugating nuclei represents the second male cell 
and that there is here a true case of wdiat has been called double 
fertilization ; while in the second instance the conjugating nuclei 
were embryo- sac nuclei, since the pollen tube had not yet entered 
the sac. 
Soon after the eight-celled sac is formed it begins to grow very 
rapidly in the direction of the longitudinal axis of the ovule. 
The cells of the tissue below the antipodal region of the sac 
become greatly enlarged and between them are large intercellular 
spaces. Usually there is a single row of cells very rich in cyto- 
plasm, which becomes very prominent in the preparations because 
of its deep stain. This row extends downward from the base of 
the sac toward the lower end of the ovule (Fig. 14). The cells 
surrounding this axial row become much larger in size and then 
disintegrate, leaving a large space filled with thin cytoplasm 
(Fig. 18). The cytoplasm of the embryo-sac extends down to 
the axial row of cells ( Fig. 14). These central cells are present 
some time after the adjacent cells have disappeared, and .since 
they are rich in cytoplasm, it seems that the}’ serve as a conduct- 
ing passage for food from the lower ovular tissue to the cytoplasm 
above, which in turn carries the food to the egg apparatus. 
After fertilization the axial row begins to degenerate and then 
disappears entirely, leaving a cavity reaching far back into the 
tissue of the ovule (Fig. 21 ) Sometimes the nuclei of the axial 
row of cells become active and divide (Fig. 20), and are after- 
wards found massed together in the lower part of the cavity after 
their walls have disappeared (Fig. 21). The cavity formed by 
the disintegration of the cells below’ the antipodal region enlarges 
greatly while the embryo is developing and into it the two basal 
lobes of the embryo are rapidly extended, their outer surface 
lying in contact w'ith the walls of the cavity. 
The first division of the definitive nucleus occurs about the time 
of the formation of the two- celled embryo and a very delicate 
wall is formed between the two daughter nuclei which divides 
the embryo-sac into two chambers. A division of one of the two 
endosperm nuclei thus formed takes place and a second w’all is 
formed across the sac so that there are then three superposed 
