540 Brown: EMBRYO-SAC AND EMBRYO IN PHASEOLUS 
is entirely absorbed after fertilization; Ward (1881) notes the 
deliquescence of the cells surrounding the embryo-sac of Lupinus 
venustus; and Martin (1914) made similar observations on Medi- 
cago sativa, Vicia americana, and several species of Lupinus. 
THE EMBRYO 
The first division of the fertilized egg is transverse (FIG. 18); 
the basal one of the two cells so formed typically encloses a large 
vacuole. The next division occurs in this basal cell and is trans- 
verse (FIG. 19), so that a filamentous pro-embryo of three cells is 
invariably formed (Fic. 20). The third division is a longitudinal 
one (FIG. 21), in the terminal cell; it is quickly followed by longi- 
tudinal divisions in the other two cells of the pro-embryo, which 
are to give rise to the suspensor (Fic. 22). Divisions may now 
occur in the longitudinal plane perpendicular to that just described, 
or the divisions in the second longitudinal plane may be pre- 
ceded by several transverse divisions. The embryo then consists 
of four rows of seven or eight cells each (Fic. 23); and the basal 
cells have begun to show evidences of swelling. 
Division now ceases except in the cells at the distal end of the 
embryo. Anticlinal walls are put in (Fic. 24, a) in the cells of the 
terminal tier. Periclinal walls are next formed, cutting off an 
outer layer of cells, the dermatogen (Fic. 26). In Medicago 
sativa, Vicia americana, and several species of Trifolium, Martin 
(1914) observed that the dermatogen is cut off later than the 
octant stage; Guignard (1881) also found this true in his work on 
Phaseolus multiflorus. When the embryo is about six or seven cells 
in length (Fic. 24), the four basal cells of the suspensor become swol- 
len and turgid and much elongated; later the next tier of four cells 
above them also undergo like changes (Fic. 25). The swollen 
cells at the base of the suspensor continue to grow in length and 
retain their inflated appearance until late in the history of the 
embryo; but when the embryo has grown so as almost to fill the 
cavity of the sac, its growth seems to cause a compression of the 
basal cells and they become flattened in the micropylar end of the 
embryo-sac (FIG. 27). Swollen suspensor cells occur in other 
members of the Leguminosae; Hegelmaier (1880) reported such 
cells in the embryo of Lupinus, but in this case the cells were 
