THE PEUIT. 141 



structures. It constitutes the case enclosing the ripe seed or 

 seeds, and is called the pericarp. The pericarp is of very different 

 structure in different fruits. When the fruit is mature, it may be 

 dry, membranous, leathery (coriaceous), ivoody, or succulent ; or it 

 may be succulent externally and woody within, or succulent in- 

 ternally and woody or leathery outside. 



The ripe pods of common Peas afford examples of a dry membranous 

 pericarp ; the Flags (Iris) have a leathery pericarp ; the common Hazel- 

 nut &c. have a woody pericarp. The pericarps of the Grape and the 

 Gooseberry are succulent or baccate. The Plum, Cherry, &c. are succu- 

 lent, externally and woody within (drupaceous) ; the Orange, the Pome- 

 granate, the Pumpkin, &c. are succulent within and leathery or horny 

 outside. 



When the pericarp is uniformly membranous or woody, without dis- 

 tinction of layers, no subdivisional terms are applied to it. The same 

 holds good in respect to the simple succulent pericarp of such fruits as the 

 Grape and Gooseberry. When there is a distinction into layers, formed 

 by a gradual alteration of the texture of the inner and outer parts during 

 maturation, we distinguish between an epicarp and an endocarp orpyrene 

 as, for example, in the Plum, Cherry, Walnut, &c., where there is a suc- 

 culent epicarp, and a woody endocarp forming the " stone ; " the l( core " 

 of the Apple is a membranous endocarp. When a fruit, such as the 

 Orange, Pomegranate, Litchi, &c., is firm externally, with a leathery or 

 woody epicarp and a succulent endocarp, the latter is generally derived 

 from development from the placental regions. In common " stone-fruits " 

 the two regions are often distinguished by the names sarcocarp (or pulp) 

 and putamen orpyrene. In the Date-Palm (fig. 280) the " stone " consists 

 of the albuminous seed, which is invested by a succulent pericarp. In 

 other Palms, such as Areca, the pericarp is fibrous. In hard-rinded suc- 

 culent fruits we have an internal sarcocarp enclosed by a cortex or rind. 



Many authors, following De Candolle, divide the pericarp into epicarp, 

 mesocarp, and endocarp. It may be observed here that the distinction 

 between endocarp and epicarp, in the common stone-fruits, arises entirely 

 during the ripening of the fruit ; the two regions are originally alike and 

 undistinguishable ; it is well known that the easy separation of the pulp 

 from the stone is a sign of ripeness. 



Dehiscence of Fruit. Some fruits, more particularly the succu- 

 lent kinds, but also many dry fruits, do not burst to discharge 

 their seed or seeds when ripe ; these are called indeJiiscent fruits. 

 The pericarp rots away, or is broken irregularly or perforated 

 when the seed germinates. Most dry fruits, more particularly 

 those formed of more than one carpel, burst open or separate into 

 pieces in a regular manner when mature, and are consequently 

 dehiscent. 



Dehiscence takes place generally (1) by the separation or splitting 

 of the sutures of the carpels in a vertical direction, or (2) by the disso- 

 ciation of coherent carpels, or (3) by both together. The parts which 



