FRUIT. 87 



13. A carpel may be compared, as we have before said, to 

 a leaf folded upon itself (that is, the edges rolled inwards to- 

 wards its midrib), and, like it, is composed of three layers ; 

 namely, an external membrane, which represents the epider- 

 mis of the inferior surface of the leaf, and in the fruit is named 

 epicarp (from the Greek, epi, upon, and karpos, fruit) ; a middle 

 layer, which is analogous to the paren'chyma of the leaf, and 

 is called the mesocarp (from the Greek, mesas, the middle, and 

 karpos, fruit), or sarcocarp (from the Greek, sarx, flesh, and 

 karpos, fruit, flesh of the fruit) ; finally, an internal membrane 

 or en'docarp (from the Greek, endon, within, and karpos, fruit), 

 which corresponds to the superior surface of the leaf; also, 

 the pericarp, which is nothing but the united or 

 agglutinated carpels, is essentially composed of 



three layers ; namely, the epicarp, which occupies 

 the surface of it, the mesocarp, which is more deeply 

 situated, and the endocarp, which lines the lodges or 

 cells in which the seeds are found. 



14. The epicarp frequently has upon its sur- ^ JC * ' 

 face, hairs, glands, and stomata ; in general, it is 



thin and flexible, and is often easily detached from the subjacent 

 parts ; it is this membrane which forms the velvety skin of the 

 peach and of the plum. When the ovary is infra, that is, when- 

 ever it is united with the tube of the calyx, it is this tube which 

 constitutes the epicarp, and then we always distinguish at its 

 superior part, the teeth or divisions of the limb, or at least a 

 border formed by the remains of this part of the floral envelope, 

 which fades after fecundation (Jig. 116, &). 



15. The mesocarp is the parenchy'matous portion in which all 

 the vessels of the fruit are united. It frequently presents a very 

 considerable thickness and a fleshy consistence (which has ob- 

 tained for it the name of sarcocarp), as in the peach, the apricot, 

 the cherry, &c., and constitutes the part we eat. Sometimes the 

 mesocarp is dry and fibrous, as in the almond, or it constitutes the 

 part called the sJiell ; and at other times it is so thin as to be 

 hardly distinguished. 



16. The endocarp which internally lines carpels or ovaries, 

 and constitutes the layer of the pericarp nearest the seed, varies 

 much. In most fruits it is thin and transparent (as in the husk 



Explanation of Fig. 117. Fruit of a palm tree opened; a, the peri 

 carp, composed of three layers, called epicarp, mesocarp, and endocarp ; 

 b, the seed ; c, its embryo. 



13. Of what parts is a carpel composed ? 



14. What is the epicarp ? 



15. What is the mesocarp? 



16. What is the endocarp ? 



