a cells” divided, in 1904, during w 
1917] DUPLER—TAXUS CANADENSIS Ei7 
sporangium develops during the summer, and by the time men- 
tioned the microspores are forming (figs. 2-12). In a single 
strobilus all stages from spore mother cells to completed tetrads 
_may be found. Different stages are also found in a single sporan- 
gium, although here the range is not so great as in case of the 
entire strobilus. 
Reduction in the chromosome number and the formation of 
microspores take place as the result of the usual two divisions of 
the mother cell. The first division (figs. 2-5) results in two 
hemispherical cells, and this is followed by the second division 
(figs. 6, 7), usually in the same plane, resulting in the bilateral tetrad 
of microspores, although the two planes of division may sometimes 
be.at right angles to one another. Sometimes the second divisions 
are not simultaneous (fig. 8). Further divisions may also occur, 
resulting in the formation of more than 4 microspores from a single 
mother cell, as many as 6 having been found (figs. 9-12). The 
microspores soon separate from one another and become surrounded 
by moderately heavy spore coats (fig. 13), the tapetum remaining 
quite prominent and showing little signs of disintegration even at 
this time. The microspore stage is the winter condition of the 
microsporangium, the only noticeable change in the microspores. 
between this and pollination being an increase in size (figs. 13, 14). : 
, This growth takes place in the early spring, during the period in 
which the strobilus i from the winter scales and piaene 
its mature size (about the middle of April). 
Torreya californica in England (10) and T. peti in : 
- Florida (14) pass the winter in the mother cell condition. STRas- 
BURGER (12) reports that in Taxus baccata the “pollen” mother : 
: ay So far as fal gies T. ‘canadensis is is ; the only one of the : 
