458 BOTANICAL GAZETTE [DECEMBER 
that of the body cell very dense. The tube nucleus begins to dis- 
integrate before the pollen tube emerges from the exine; usually 
during the pollen tube stage it appears only as an irregular aggre- 
gation; seldom, if ever, does it enter the egg. 
A number of gametophytes have been found similar to that 
shown in fig. 2. The first division has cut off a polar (“‘prothallial’’) 
cell which later has disintegrated; the second division has given 
rise to two equivalent cells; which of the two might have been 
regarded as prothallial, under other circumstances, is impossible to 
determine. Evidently there are two antheridia. The conclusions 
based on a study of Picea (9), namely, that under favorable condi- 
tions any of the cells resulting from the three primary divisions of 
the male gametophyte may be antheridial, are supported by the 
facts as found in Abies. 
The period of time between pollination and fertilization is from 
four to five weeks. During the greater part of this time the pollen 
grains lie dormant on the nucellus, or lodged in the micropyle. The 
course of the pollen tube is direct, and the motion rapid. Although 
the rate is difficult to determine, it is believed that the passage 
time of the pollen tube does not exceed two days, and probably may 
be measured in hours. 
Fertilization of the ventral canal cell 
The division of the central cell to form the egg and the ventral 
canal cell is similar to that in Pinus (figs. 7, 8, 9; compare, 3, 5, 
6, 19); the nuclei formed are similar in size and form. The egg 
nucleus at once begins to move toward the center of the egg cyto- 
plasm (fig. 7). What the attractive force may be is unknown, but 
the nucleus of the ventral canal cell responds to the same force and 
moves in the same direction. This nucleus breaks through the 
cell wall and enters the cytoplasm of the egg (figs. 11, 12); here it 
increases in size until it reaches a length, in some cases of 80H, 
which is approximately one-half of the greatest length attained by 
the egg nucleus. The structure of the ventral nucleus is very simi- 
lar to that of the egg, which will be described later. The latter is 
surrounded by a dense granular layer which is not present in the 
case of the former. 
