4 BOTANICAL GAZETTE [JANUARY 
Even in the binucleate condition the sac is considerably elongated 
(fig. 28); it continues to grow more in length than in breadth; 
finally it becomes slightly curved and also somewhat enlarged at 
the ends. The tetranucleate sac is shown in fig. 29. The mature 
sac is of the ordinary type, containing an egg and two beaked syner- 
gids at the micropylar end, three antipodals at the opposite end, 
and two endosperm nuclei somewhat above the middle (figs. 8, 
Q; IO, oO). 
While fertilization was not observed in either species, there 
can be little doubt of its occurrence in both. The evidence for this 
is that when material of a certain age is examined the remains of 
the pollen tube are invariably found in the micropyle and also 
within the embryo sac (fig. 31). 
In all the sacs of Magnolia in which the polar nuclei were found, 
partial fusion had already occurred (fig. 30). After fusion the 
endosperm nucleus moves close to the egg apparatus, and then, 
before division of the (presumably fertilized) egg, the first division 
of the fusion nucleus takes place. At this division a wall is formed 
transverse to the long axis of the embryo sac (fig. 31), hence the 
endosperm is cellular from the start, differing from Drimys (29) in 
this respect. Both of the resulting cells participate in the forma- 
tion of the endosperm, that part of the sac surrounding the egg 
becoming filled with endosperm much more rapidly than the 
antipodal end. In early stages the endosperm is quite compact 
(fig. 32), but later the cells seem to enlarge; finally, in the mature 
condition, the nucellar tissue disappears completely and an abun- 
dant supply of compact endosperm fills the seed. 
In the development of the embryo of Magnolia the first division 
is transverse; the second longitudinal to the long axis of the embryo 
sac (fig. 33). A second longitudinal wall separates the young 
embryo into octants (fig. 34), and soon thereafter the divisions 
apparently become quite irregular (fig. 35). There is much 
difference in the form of different embryos of approximately the 
same age, some being nearly globular (fig. 35) and others con- 
siderably elongated. A well defined suspensor (fig. 36) appears 
somewhat late and may persist until the embryo is mature. The 
cotyledons are initiated after the embryo has enlarged considerably. 
