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 emhryo-sacs instead of spores) never he- 

 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 oi 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 (macrospore) produces a first stage 

 (prothallium) and one or more archegones, as in the higher 

 Lycopods. The archegones are usually much simplified, 

 and in the higher plants they consist of little more than the 

 germ-ceUs. The prothallium for the most part does not 

 develop until after the germ-cell has reached maturity. It 

 is a belated growth; having lost nearly all of its former 

 usefulness as a supporting and nourishing tissue for the 

 sexual organs, its development is more or less retarded. 



456. Fertilization of the germ-cell takes place essentially 

 as in plants 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 



