726 
DUNCAN S. JOHNSON 
course possible that some of these variations from the usual 
arrangement of nuclei in the four-nucleate stage, are connected 
with the phenomenon of degeneration of the sac which is of not 
infrequent occurrence, to judge from shrunken sacs found in 
the older spikes. 
In an early eight-nucleate stage the nuclei are found gathered 
in tw^o groups of four each, one at the upper, one at the lower end 
of the sac (fig. 59). Somewhat later than this an egg apparatus, 
of the usual three-celled type, is found at the upper end of the 
sac. Three antipodals are grouped at the base, and two polar 
nuclei meet at the middle of the sac (fig. 60). 
Pollen tubes, and the details of fertilization, have not been 
seen, but, from the number of cases where two nuclei were seen 
in the egg, (fig. 54), there seems no reason to doubt that fertili- 
zation is accomplished in the normal manner. No evidence of a 
triple fusion has been noticed. The early stages of development 
of the embryo and endosperm have not been found, but in seeds 
that have grown to twelve times the diameter of one containing 
a just-ripe sac, the fertilized egg is still undivided, though the 
endosperm nucleus has given rise to scores of free nuclei in the 
peripheral cytoplasmic layer of the sac (fig. 63). The antipodals 
at this time have already multiplied to a number which may be 
as great as 35 in a single section of the sac. They occupy a large 
space at the base of the sac (figs. 61, 62). In the ripe seed the 
antipodals, somewhat crushed, can still be seen in a depression 
below the endosperm (figs. 65, 70). 
The endosperm develops cell-walls after about 100 or more 
free nuclei have been formed, the walls apparently arising in the 
ordinary way. In the mature seed the endosperm forms an irreg- 
ularly globular mass about 700)u in diameter, and showing about 
150 cells in a median longitudinal section of the seed and embryo 
sac. The cells of the ripe endosperm contain little, if an}^, starch 
but hav^e rather dense protoplasmic contents, Avhich may serve 
as a store of nitrogenous material. . The chief carbohydrate sup- 
ply of the seed is stored in the starch}^ perisperm, which makes 
up 99|% of the bulk of the seed (fig. 65). 
