166 
ELEMENTS OF BOTANY 
ovule m, in Fig. 124, reaches one of the cells shown at e, 
and transfers a sperm nucleus into this egg-cell. 
Fia. 124. Diagrammatic Representation 
of Fertilization of an Ovule. 
z, inner coating of ovule; o, outer coating 
of ovyule; p, pollen tube, proceeding from 
one of the pollen grains on the stigma; 
ce, the place where the two coats of the 
ovule blend (the kind of ovule here 
shown is inverted, its opening m being at 
the bottom, and the stalk f adhering along 
one side of the ovule); @ toe, embryo sac, 
full of protoplasm; @, so-called antipodal 
cells of embryo sac; 7, central nucleus of 
the embryo sac; e, nucleated cells, one 
of which, the egg-cell, receives the essen- 
tial contents of the pollen tube; f, funi- 
culus or stalk of ovule; im, opening into 
the ovule. 
The 
latter is thus enabled to 
divide and finally grow 
into an embryo. ‘This 
the cell does by forming 
cell-walls and then 
increasing by continued 
subdivision in much the 
same way in which the 
cells at the growing 
point near the tip of the 
root subdivide. 
194. Nature of the 
Fertilizing Process. — 
The necessary feature of 
the process of fertiliza- 
tion is the union of the 
essential contents of two 
cells to form a new one 
from which the future 
This 
kind of union is found 
plant is to spring. 
to occur in many erypto- 
gams (Chapters XXII- 
XXV), resulting in the 
production of a spore 
capable of growing into 
a complete plant. 
1See Strasburger, Noll, 
Schenk, and Schimper’s Tezxt- 
Book of Botany, pp. 442-46. 
