232 Nichols, A morphological study of Juniperus communis var . dcpressa. 
nuclei the outline of the original nucleus disappears, and the 
surrounding layer of cytoplasm and starch presses in and invests 
the two daughter nuclei. The latter grow rapidly and enter npon 
a briet period of rest (fig. 107). 
Shortly after the completion of the first Segmentation division 
the daughter nuclei diyide (fig. 108), giving rise to four resting 
nuclei which are usually arranged in a tetrad, as shown in fig. 109. 
There is no rule as to the Position of the spindles of this division 
with respect to the axis of the archegonium, and in this, as well 
as in the following division, the spindle is of intra-nuclear origin. 
Fig. 110 represents the third free nuclear division (the fourth 
dividing nucleus appears in the next section). In this figure the 
chromosomes have obviously split longitudinally, although they are 
just being oriented at the equator. After the Organization of the 
eight nuclei which result from this division wall formation usually 
takes place, as already described by Noren (1907) in the European 
form, and in this respect Juniperus agrees with the Abieteae and 
Cupresseae thus far investigated. Occasionaliy, however, sixteen 
free nuclei may be formed before the separating membranes are 
laid down (fig. 111), thus approaching the condition found in Po- 
docarpus (Coker 1902) and Cephalotaxus (Coker 1907, Lawson 
1907 a) where sixteen are normally produced. 
Of the eight cells which are usually cut off by the formation 
of walls the three or four which will give rise to the embryo lie 
at the base of the archegonium, while the remaining cells form a 
well defined tier above these. The latter are not entirely enclosed 
by walls, being exposed above to the cytoplasm of the egg, and 
they soon divide, giving rise to two tiers of cells (figs. 112, 113). 
Of the cells thus formed those of the upper tier constitute the 
rosette, and, as in most conifers, they never become enclosed above 
by a wall. The cells of the lower tier are the suspensors, by the 
elongation of which (fig. 114) the embryo is pushed deep into the 
endosperm. Simultaneously with the cell division just described 
the cells of the embryo proper usually undergo division (fig. 112). 
The further development of the embryo has not been followed by 
the writer. 
Summary. 
The buds which give rise to the staminate cones are formed 
during the summer of the year preceding pollination. 
The archesporium originates from one or more hypodermal 
cells at the base of the sporophyll. 
The tapetum and the inner layer of the sporangium wall are 
both derived from the outermost cells of the archesporium, while 
the outer layer of the wall — the only layer present in the mature 
sporangium — is developed from epidermal cells. Thus the inner 
layer of the wall is more closely correlated to the tapetum than 
to the outer wall-layer. 
