1917] DUPLER—TAXUS CANADENSIS 125 
the formation of young female gametophytes (figs. 39-44). The 
further development of several megaspores will be described later. 
Some interesting cases were found, such as those in which one of the 
upper megaspores had evidently functioned, while the lower ones 
had failed to develop, although still recognizable (figs. 30, 31). 
In both cases figured the pollen tubes have pushed past the gameto- 
phytes and penetrated to the central region of the nucellus. 
THomson (15) in his investigation covering the megaspore 
membrane situation in the gymnosperms reports that in Taxus 
canadensis the megaspore membrane, while recognizable in the 
early free nuclear stages of the gametophyte, is practically unrecog- _ 
nizable in later stages. This agrees with my observations that the 
membrane is quite firm about the young female gametophyte, but 
seemingly fails to develop with the endosperm and is soon lost sight 
of. THOMSON associates this with the absence of the ‘primary 
tapetum”’ and regards it as a specialized advanced character, indi- 
cating that the Taxineae are “recent”’ as compared with some other 
forms. 
DEVELOPMENT OF FEMALE GAMETOPHYTE 
Free nuclear stage—The first division of the functional sae : 
Spores takes place soon after their formation, and other divisions, 
which are always simultaneous, follow in rapid succession (figs. ‘ 
45,46). Th ; as the number of nuclei increases. . : 
At first the nuclei are scattered i in the embryo sac, but as this 
increases in si lated in the center, the cytoplasm — 
with the nuclei dies alleg 6 paiphaeal position, —— 
