CAMPBELL: EMBRYO-SAC OF PANDANUS CORONATUS 295 
represent the polar nuclei of the ordinary embryo-sac. In this 
specimen the pollen-tube had not yet reached the nucellus. 
Several somewhat older stages were also examined, some of 
which showed the entrance of the pollen-tube. In FIGURE 3 the 
pollen-tube is seen within the embryo-sac—where it has partially 
destroyed one of the synergids. Two small nuclei, probably the 
generative nuclei, could be seen within the pollen-tube. The egg, 
0, lay some distance below the synergids, but this was probably 
due to displacement in mounting the sections. Two sections of 
the antipodal region are shown in FIGURES 4 and 5. There were 
three polar (?) nuclei, apparently in process of fusion. 
In another specimen (FIGURE 6) there were six ‘‘polar’’ nuclei. 
It is thus evident that at the time of fertilization, the embryo- 
sac of Pandanus has a very much larger number of cells than that of 
the typical angiosperms, this being shown both in the increased 
number of antipodal cells, and that of the ‘“‘polar’’ nuclei. 
It still remains to be seen what is the relation of the “polar’ 
nuclei to the egg-apparatus and to the antipodals. 
The embryo-sac of Pandanus most nearly resembles that of 
Sparganium, but in the latter the increased number of antipodal 
cells arises subsequently to fertilization, and there are but two 
polar nuclei. The structure of the embryo-sac tends to confirm 
the view that the families Pandanaceae and Sparganiaceae are 
really closely related. (See arrangement of the families of mono- 
cotyledons in Engler & Prantl, Die Natiirlichen Pflanzenfamilien.) 
STANFORD UNIVERSITY, 
CALIFORNIA. 
’ 
