166 
ESSENTIALS OF BOTANY 
ovule m, in Fig. 124; reaches one of the cells shown at e, 
and transfers a sperm nucleus into this egg-cell. 
Matt 
afc i 
We 
Fic. 124. Diagrammatic Representation 
of Fertilization of an Ovule. 
dz, inner coating of ovule; vu, outer coating 
of ovule; p, pollen tube, proceeding from 
one of the pollen grains on the stigma; 
c, 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 
oneside of the ovule) ; a toe, embryo sac, 
full of protoplasm; a, so-called antipodal 
cells of embryo sac; 2, central nucleus of 
the embryo sac; e, nucleated cells, one 
of which, the egg-cell, receives the essen- 
tial contents of the pollen tube; /, funi- 
culus or stalk of ovule; m, 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 
Srom which the future 
plant is to spring. This 
kind of union is found 
to occur in many crypto- 
gams (Chapters XXIII- 
XXVII), resulting in the 
production of a spore 
capable of growing into 
a complete plant. 
1See Strasburger, Noll, 
Schenk and Karsten’s Tezxt- 
Book of Botany, pp. 442-446. 
