1908] COULTER—GNETUM GNEMON 45 
ENDOSPERM 
A year later, the endosperm has destroyed all of the nucellar 
tissue except a very small amount at the tip (jigs. 6, 6a, 7a), and it 
is clearly differentiated into a central region of smaller, more compact 
cells, and a more extensive peripheral region of larger and looser 
cells. In destroying the nucellar beak, a curious result is observed. 
The central region of the endosperm advances into the beak and 
then spreads laterally (jig. 6). In the meantime the peripheral 
region advances more slowly toward the beak, and as a consequence 
a ring of nucellar tissue is pinched between two growing masses of 
endosperm. The growth of the endosperm into the chalazal region - 
also results in pressure toward the beak, so that the pinched nucellar 
tissue is under considerable pressure and becomes completely disor- 
ganized. Under this pressure some of the adjacent endosperm cells 
also become disorganized. | 
Tn ovules of the preceding year, at the fertilization stage of the 
embryo sac, a curious disorganization of some of the cells of the 
nucellar beak was observed (fig. 5a). Two transverse rings of cells, 
several layers beneath the epidermis, begin to disorganize; later the 
epidermis becomes involuted between the disorganized rings, resulting 
In a deep groove around the nucellus. The epidermal cells remain 
rh Vigorous in appearance, and when the endosperm develops into 
this region the groove disappears. The cause and the significance 
of this disorganization and of the temporary. involution of the epi- 
dermis cannot be suggested. 
EMBRYO 
Lotsy has described the entrance of pollen tubes into the embryo 
Sac, the fertilization of the free eggs, the excessive elongation of the 
fertilized eggs to form suspensors, and the cutting-off of the embryonal 
cells at the tip of the suspensor. Later stages in the development 
of the embryo have been described by Bower,‘ but the intermediate 
Stages have not been observed. Fortunately our material from the 
Philippines contained them, and revealed an unexpected situation. 
When the endosperm has become fully developed, its peripheral 
4 . : 
Se Ra Da rata hi ete Om 
