Fertilization in Pinus Strobus . 439 
of this tubular cavity often become very closely crowded 
together so that the passage is obscured. 
The number of archegonia in a single ovule varies in Pinns 
Strobus , P. rigida , and P. resinosa from one to five, the most 
usual number being three. In Pinus austriaca and P. mon- 
tana } var. uncinata , the number is larger, averaging about 
five ; as many as nine have been observed in a given pro- 
thallium in Pinus Montana , var. uncinata. The form of the 
mature egg depends largely upon the number and arrangement 
of the archegonia. When there are not more than two or 
three, as is frequently the case in Pinus Sir obits, they may 
become almost spherical in outline. 
Division of the Central Cell. 
As the central cell prepares for division, the cytoplasm 
between its nucleus and the neck-cells is apparently resolved 
into fine granules, and there is a more or less pronounced 
condensation of the protoplasm about the lower side of the 
nucleus. At the same time the nucleolus disappears wholly 
or in part, the nuclear reticulum becomes more open and 
broken, and the chromatin collects or condenses at various 
places on the network (Fig. 14 ). Soon a clear court, similar 
to that described by Hof (’98), Fulmer (’98), Nemec (’98 and 
’99), Strasburger (1900) and others, makes its appearance 
along the lower half of the nucleus ; inasmuch as this nucleus 
is pressed close against the neck- cells such a court does not 
arise along its upper side (Figs. 1 5 and 16 ). Delicate, granular 
threads cross this court and press against the nuclear 
membrane ; at the same time the upper and lower surfaces of 
the nucleus become irregularly indented (Fig. 17 ). As the 
chromatin condenses to form the spirem, an achromatic net- 
work, as already described for the corresponding stage in the 
division of the generative nucleus in Pinus> becomes apparent 
in the nuclear cavity (Figs. 14 - 17 ). When the spirem is fully 
established it presents a beautiful moniliform appearance and 
the longitudinal splitting of the band becomes apparent ; at 
this time the threads which earlier arose in the cytoplasm 
