Nichols, A morphological study of Juniperus communis var. depressa. 217 
matin and linin proper, there is evident in the nucleus a delicate 
protoplasmic network. The presence here of these three seemingly 
distinct nuclear elements in not necessarily at variance with 
the conditions fonnd in the microspore mother cells, where it is 
impossible to make out such a differentiation, since many writers, 
especially among the zoologists, maintain that both “nucleus and 
cytoplasm have arisen through the differentiation of a common 
protoplasmic medium” (Wilson 1900, p. 40), and that the various 
elements in the cell are merely different physiological expressions 
of the same substance (see also Chamberlain 1899, p. 277). 
Fig. 56 shows a later stage in the division. The spirem has seg- 
mented into twelve slender and often twisted chromosomes, while 
the distinction between chromatin and linin has disappeared. At 
the same time delicate granulär fibers have arisen in the nucleus. 
The chromosomes rapidly become shorter and thicker and are 
oriented at the equatorial plane while the übers give rise to a 
blunt, multipolar diarch spindle (fig. 57), and the nuclear membrane 
disappears. As shown in the figures, no indications of a fibrillär 
structure are as yet present in the cytoplasm outside the nucleus, 
although Sludsky’s figure would lead one to look for them. 
Fig. 58 represents the late telophase of this division. A cell plate 
has been forined extending entirely across the cell, and the 
connecting fibers are still evident. The nuclei have reorganized, 
and the chromatin appears to be in the form of small granules — 
the pseudonucleoli of Noren (1907) — suspended in a network of 
linin, as was described by Lawson (1904b) in Cryptomeria. 
The megasporangium. 
Development of the megaspore mother cell. — Noren 
(1907) finds in the European J. communis that soon after polli¬ 
nation a group of several cells, the archesporium, becomes re- 
cognizable in the lower portion of the nucellus, one of which 
becomes the megaspore mother cell. The non-functioning arche- 
sporial cells give rise to the tapetum, which surrounds the de- 
veloping embryo sac and persists until after the formation of the 
endosperm. The tetrad divisions take place early in the year 
following the appearance of the archesporium and generally give 
rise to three cells, one of which is the functional megaspore. 
Düring the first of these divisions a reduction in the number of 
chromosomes is effected in the same manner as in the microspore 
mother cells. 
The buds which give rise to the pistillate flowers in var. 
depressa are formed during the latter part of the growing season 
which precedes pollination. They are borne in the axils of the 
leaves on branches of the same year. In material collected less 
than five weeks before pollination it is impossible to distinguish 
vegetative from flower buds, but four weeks later (May 19) the 
ovules have begun to develop and present the appearance shown 
