Brown: EMBRYO-SAC AND EMBRYO IN PHAsEoLUS 541 
multinucleate; Strasburger (1880) observed swollen suspensor 
cells in Lupinus, which in some instances show a tendency to 
separate from one another. Guignard (1881) also reported the 
occurrence of inflated cells which are multinucleate in Orobus 
aureus, O. angustifolius, and Pisum sativum, and suspensor cells 
which become separated from one another in Lupinus polyphyllus. 
Martin (1914) observed instances in his studies in which the sus- 
pensor cells retained their normal appearance and also cases in 
which the modifications which were noted by other investigators 
occurred. 
At the time of the differentiation of the dermatogen, the em- 
bryo proper is almost ovoid in shape (Fic. 26); it retains this form 
as it increases in size until the appearance of the cotyledons. 
Cotyledon development begins later than the stage shown in 
Figure 26; but none of my preparations show satisfactorily the first 
stages in this development because the plane of the union of the 
cotyledons is parallel to the flat side of the ovule, and the embryo 
lies curved in the micropylar end of the embryo-sac. The embryo 
continues to grow at the expense of the endosperm and of the 
cushion of nucellar tissue at the chalazal end .of the embryo-sac. 
The nucellus is absorbed, and by the time the embryo is mature 
the endosperm also has entirely disappeared. 
THE ENDOSPERM 
The division of the primary endosperm nucleus as a rule pre- 
cedes that of the fertilized egg (F1G. 17), although one preparation 
showed the egg nucleus and the primary endosperm nucleus divid- 
ing simultaneously. In Phaseolus multiflorus, Guignard . (1881) 
found that the division of the egg nucleus and that of the primary 
endosperm nucleus occur at the same time; Strasburger (1880) 
observed the simultaneous division of these two nuclei in Lupinus; 
but Martin (1914) found that the first division of the fertilized 
egg is usually preceded by the first division of the primary endo- 
sperm nucleus. 
The endosperm nuclei resulting from the first two divisions 
arrange themselves in the periphery of the embryo-sac. Usually 
two of them are to be seen near the young embryo, one on either 
side of it. The later nuclear divisions are not always simulta- 
