414 PART IV. CLASSIFICATION. 



cell (female pronudeus] approach each other and fuse into one 

 the two protoplasms likewise fusing. Fertilisation is now com- 

 plete ; in consequence, the oosphere surrounds itself with a cell- 

 wall, becoming the oospore. and begins to develope into the embryo- 

 sporophyte. Further details are given in the sections on Gymno- 

 sperms and Augiosperms respectively. 



The Results of Fertilisation. The most direct result of fertilisa- 

 tion is the development of the embryo (see p. 401) from the oospore, 

 a process which involves the conversion of the ovule into the seed. 

 But the effect of fertilisation is not limited to this : a process of 

 growth is initiated in various other parts of the flower so that 

 they undergo marked changes in structure, accompanied by con- 

 siderable increase in size, the product being the structure known 

 as the fruit (p. 61). In some cases the carpels only are affected, 

 besoming either fleshy and succulent (e.g. Plum), or dry and hard 



(e.g. Poppy) ; in others, 

 the floral axis becomes 

 fleshy (e.g. Strawberry) ; 

 in others again the peri- 

 anth-leaves also (e.g. 

 Mulberry). It is con- 

 venient to regard as 



F. 245,-Sections of ripe seed. A * ~, * A* Only those 



showing E endosperm. B Piper, showing both endo- which are developed from 



sperm E, and perisperm P. C Almond, devoid of the gynseceum a l one ; 

 endosperm; s the testa; e embryo; oe its radicle; 



c cits cotyledons. an d as false fruits, or 



pseudocarps, those in 



the formation of which other parts of the flower or of the inflor- 

 escence take part. 



The seed (p. 62) is produced from the ovule, as a consequence of 

 the fertilisation of the female cell contained within the ovule : its 

 characteristic feature is that it contains an embryo. The seed 

 (Fig. 245) may contain little or nothing but the embryo, in which 

 case it is said to be cxalbuminous (e.g. Pea, Bean, Sunflower, 

 Almond, Oak) : or it may contain, in addition to a small embr} r o, 

 a considerable portion of the female prothalliam (endosperm), when 

 it is termed albuminous (e.g. Grasses and other Monocotyledons, 

 Ranunculacese) : in a few rare cases the albuminous seed contains, 

 in addition to the embryo and endosperm, some of the nucellar 

 tissue of the macrosporaugium which is termed perisperm (e.g. 

 Nymphseacese, Zingiberaceae) : in Canna, Chenopodiacese, etc., 4 



