THE MORPHOLOGY AND AFFINITIES OF GNETUM 1 69 
tube enters, the same rapid divisions occur throughout the sac and 
result in the production of a large number of small nuclei. But in 
these forms wall formation also takes place in the expanded part of 
the sac in the vicinity of the egg. It is particularly easy to observe 
it here. The spindle fibers of the last few divisions remain and con-* 
sequently each nucleus is connected by fibers with several others. 
The walls are formed across these groups of fibers in the usual way. 
Not all the groups, however, are involved and consequently compart- 
ments are formed containing several nuclei (see fig. 62). The fibers 
not involved in wall formation disappear. The result is a group of 
multinucleate compartments in which fusion of the nuclei occurs as 
described for G. gnemon. The compartments are formed first in the 
vicinity of the egg and around the end of the pollen tube. Conse- 
quently at fertilization time one finds this group of cells surrounding 
the egg and male nuclei and in the remainder of the expanded part of 
the sac only free nuclei. The latter region becomes filled with cells 
partly by the division of those already present and partly by the 
formation of new compartments among the free nuclei. 
Meanwhile endosperm has been forming down in the neck of the 
flask. Here too the process is not the same as in G. gnemon. The 
original divisions accompanied by increase in the cytoplasm, continue 
until the whole of this part of the sac becomes filled with cytoplasm 
and nuclei. In other words the vacuole becomes filled. It will be 
recalled that this part of the sac is much longer and narrower than in 
G. gnemon. The whole neck of the flask then becomes divided into 
compartments. Figure 60 shows this condition in longitudinal 
section and figure 61 in transverse section. I could not see any re- 
lation between division spindles and walls in this region; in fact the 
latter appeared to be more in the nature of cleavage walls. Eacli 
compartment contains more nuclei than in G. gnemon, but fusion 
takes place in the same way, resulting in the production of uninucleate 
cells. 
At a certain stage in endosperm formation, therefore, one finds 
cellular tissue throughout the narrow part of the sac and around the 
fertilized egg in the expanded part. Elsewhere in latter region are 
free nuclei or vacuoles (see figs. 49 and 52). The whole sac later 
becomes filled with cells by the division of those already present and 
by the formation of new ones. Further growth takes place chiefly 
in the lower end of the sac. Consequently the form of the endosperm 
