214 BOTANY. 
within outgrowths of certain modified leaves. Only a few 
are produced in each outgrowth, and of these rarely more 
than one become fully developed. Moreover, these larger 
cells (here called embryo-sacs instead of spores) never be- 
come free, but always remain within the outgrowth. 
453. We have seen that in the higher Fernworts the 
parts of the plant-body bearing the reproductive cells are 
considerably modified, often forming cones. In the flow- 
ering plants this modification is carried still further, giving 
us in the lower orders such structures as the cones of pines, 
etc., and in the higher orders the many varied and beauti- 
ful forms of flowers. 
454, The modified leaves upon which the pollen-cells are 
produced are known by the name of stamens, and the sac- 
like enlargements (corresponding to spore-cases) are com- 
monly called anthers. The outgrowths in which the em- 
bryo-sacs develop are known as ovules, and the leaves 
bearing these are the fruiting leaves, or carpophylls. 
455. The embryo-sac soon undergoes a few changes, 
somewhat similar to but much less than those in the large 
spores of the Lycopods, resulting in a germ-cell similar to 
the germ-cell of an archegone. About this time a mass of 
cells, corresponding to the first. stage of a Lycopod, devel- 
ops inthe embryo-sac. It is a belated growth; having lost 
nearly all its former usefulness as a supporting and nour- 
ishing tissue for the sexual organs, its development is more 
or less retarded. 
456. Fertilization of the germ-cell takes place essentially 
as in piants of a lower grade. When the pollen-cell germi- 
nates, it forms in a few cases a several-celled first stage 
(prothallium), reminding us again of the higher Lycopods. 
More commonly even this feeble growth of a first stage 
