308 



STRUCTURE OF FRUIT. 



contain, filled up with a very succulent cellular tissue. On the 

 other hand, in the Apple, the carpels lie in the centre of the 

 fruit, and their walls are somewhat horny ; the fleshy substance 

 of the fruit is formed by the calyx, which is adherent to the 

 exterior of the ovary; and the parenchyma between its two 

 surfaces swells out in ripening, in the same manner as does that 

 of the carpellary leaf of the Plum. In the Medlar, the carpels 

 have a hard or bony covering, and they lie separately in the 

 midst of the pulpy envelope, which they acquire in like manner 

 from the calyx. In the Strawberry, as just now mentioned 

 (. 468), the carpels are separated from each other by the recep- 

 tacle, the expansion of which forms the fleshy part of the fruit. 

 In the Raspberry and Blackberry, on the other hand, the recep- 

 tacle is the white fleshy stalk which occupies the centre of the 

 fruit ; and the pulpy portion consists of the carpels enclosing 

 seeds. The Custard- Apple of the "West Indies is formed on this 





Fie. 102. ANONA SQUAMOSA, OR CUSTARD-APPLB : a, the flower ; 

 6, fruit ; c, the same in section, showing the position of the seeds ; 

 d, seed ; e, section of the seed. 



last plan ; the edible portion consisting of the fleshy carpels which 

 are attached to a slender receptacle. The pods of the Pea, 

 Laburnum, and other Leguminous plants, again, are single car- 

 pels, which sometimes grow to a great length, and contain many 

 seeds. In the Bread-fruit (Fig. 103) and Mulberry, the edible 

 portion is formed by the cohesion, into a single mass, of the floral 

 envelopes and ovaria of a large number of flowers, arranged on 

 a central fleshy column or spike. In the Fig. on the other hand, 

 the fleshy receptacle encloses the flowers, which are situated in 

 the interior of the fruit. A great many more varieties might be 

 enumerated; but the mention of these will serve to give an idea 



