Ig15] HUTCHINSON—ABIES BALSAMEA 459 
The fertilization of the nucleus of the ventral canal cell has been 
seen in several instances. One of the male nuclei fuses with the 
ventral nucleus (figs. 15, 17, 21); the stalk nucleus also may be in 
close proximity (figs. 17, 18). Sometimes two tubes enter the 
archegonium, in which case male nuclei from different gametophytes 
may fuse with the ventral nucleus and egg nucleus respectively 
(fig. 21). The chromatin of the fusion nucleus condenses near its 
center (fig. 18), and the first division takes place. Two successive 
divisions (figs. 16, 23, 24, 26) result in four nuclei, which as might 
be expected, are generally arranged in pairs (figs. 22, 25). The 
nuclei of this ventral proembryo range in diameter from 40 to 50 y; 
those of the proembryo proper from 60 to 654; otherwise the 
similarity is very marked (figs. 32, 53, 54). 
Nuclear changes 
The changes in size of the nuclei located in the egg cytoplasm 
are the most readily measured of all the modifications; moreover, 
the increase or decrease in volume will serve to indicate the extent 
of the qualitative changes which occur. Immediately’ after the 
division of the central cell the egg nucleus measures about 30 u in 
diameter (fig. 7). At the time of fusion its length approximates 
100 w (fig. 19); during the approximation of the chromatin groups 
160 uw is the maximum measurement (fig. 27), and during anaphase 
of the first division the diameter is again reduced to 50 or 604 
(fig. 46). The changes in size of the daughter nuclei are less 
marked; the diameter varies from 20 p at telophase (fig. 52) to 65 wu 
in the resting stage It is not surprising that the egg nucleus should 
vary greatly in structure while increasing to 60 times its original 
volume, and again decreasing to one-tenth its attained volume. 
During the early stages of the first division, and even before 
the chromatin groups have united, four differentiations of the 
“nuclear” material are evident. The chromatin group or groups 
occupy less than one-tenth of the space within the nuclear mem- 
brane (figs. 27, 28, 42). The spindle fibers are intranuclear in 
origin (fig. 28). Large, vacuolate, irregular, deeply staining 
masses are distributed throughout the whole area. The greater 
part of the nuclear cavity is pervaded by slender filaments, which 
