1917] DUPLER—TAXUS CANADENSIS 119 
nearer its margins, in some cases reaching close to the edge of the 
nucellus (fig. 27). During the elongation of the tube there is also 
considerable increase in diameter, such that by the time the tube 
has reached the female gametophyte region its diameter is several 
times greater than at first (fig. 22). A striking enlargement now 
takes place. If the female gametophyte still consists of free nuclei, 
as it frequently does at this time, it may be so crowded upon by the 
enlarging tube as to be pushed to one side; or the megaspore 
membrane may remain quite firm, retaining its shape, the tube then 
being forced to-conform its shape to that of the resisting meg: 
membrane (fig. 28). A number of cases of branching tubes ¥ were 
found, the nuclear contents in such cases being near the point of 
branching, while the branches generally have dense cytoplasmic 
contents, indicating their haustorial activity. The enlarging tube 
usually spreads itself over the micropylar end of the female game- 
tophyte; it may go off to one side and penetrate far into the 
nucellus; or it may grow along the side of the endosperm, passing 
by the archegonia i in ‘the micnopyier end neil the endosperm. hes 
turn f. 
yw if 
usually enlarges between them, while i * some ¢ cases the pollen tube 
may entirely pass the developing fe: phyte and enl o 
below it. It seems that in a oe female g te tap ei 
developing from an upper megaspore (fig. 31). Ce 
In case the nucellus is is inv d by a number take they a 
produce a rather int tic ‘The female gametophyte - 
is crowded upon fron reer’ sides cud i fi 1 quite 
out of its normal shape. A case was s found of ar 
