51.] 



THE FKUIT. 



61 



and one seed, although its ovary had three cells and 

 six ovules ! This singular change is due to the non- 

 developmeiit of five of its ovules, while the sixtlf grew 

 the more rapidly, obliterated the partitions by press- 

 ing them to the wall, and filled the whole space it- 

 self. Similar changes characterize the Chestnut, Hazel- 

 nut, and that whole Order. The ovary of the Birch 

 is 2-celled, 2-ovuled; but by the sup- 

 pression of one cell with its ovule, the 

 fruit becomes 1 -celled and 1-seeded. 



165 



104 



163 



162, Section of the ovary of an acorn, 3-celled, 6-ovuled. 163, Section of ovary of Birch, 2-celled, 

 2-ovuled. 164, Vertical section of the same in fruit. 166, Pericarp of Mignonette open soon after flower- 

 ing. 166, Naked seed of Taxus Canadensis, surrounded, not covered, by the fleshy pericarp. 



On the other hand, the cells are sometimes multiplied in the fruit by the 

 formation of false partitions. Thus the pod of Thornapple (Datura) becomes 

 4-celled from a 2-celled ovary ; and the longer pods of some Leguminous 

 plants have cross-partitions formed between the seeds, and the 5-celled ovary 

 of the Flax comes by false partitions to be 10-celled (Fig. 136). 



146. The Pericarp. The fruit consists of the peri- 

 carp and the seed. The pericarp (pi, around) is the 

 envelope of the seeds, consisting of the carpels and 

 whatever other parts they may be combined with. It 

 varies greatly in texture and substance when mature, 

 being then either dry, as the Pea-pod, or succulent, as 

 the Currant. Dry pericarps are membranous, or coria- 

 ceous (leathery), or woody. Succulent pericarps may 

 be either wholly so, as the Grape, or partly so, as the 

 Peach and other stone fruits. 



147. With very few exceptions the pericarp incloses 



