292 ORGANOGRAPHY. 



The base of the fruit is that point by which it is united to 

 the thalamus ; the apex is indicated by the attachment of the 

 style, hence in those ovaries where the style is lateral or basilar, 

 as in many Eosacese (figs. 624 and 625), Labiatse (fig. 595), 

 and Boraginacese {fig. 596), the organic apex of the fruit will be 

 also thus situated, so that the geometrical and organic apices 

 will be very different. 



Pericarp. — The fruit when perfectly formed consists of two 

 parts ; namely, the shell or pericarp, and the seeds, which are 

 contained within it. In the majority of cases the pericarp 

 withers, and the fruit does not ripen, when the seeds are abortive. 

 There are, however, many exceptions to this ; thus, many 

 Oranges and Grapes produce no seeds, but the pericarp is 

 nevertheless fully developed ; and in the Bananas, Plantains, and 

 Bread-fruit the pericarps develop most extensively, and become 

 best adapted for food, when the seeds are chiefly abortive. 

 Generally speaking, however, the development of the seeds and 

 pericarp proceeds together after the process of fertilization has 

 l3een effected, and then only perfect fruit can be formed, for 

 although in common language we apply the term fruit in those 

 instances where no seeds are produced, yet strictly speaking 

 such are not fully formed fruits, but only enlarged and swollen 

 pericarps. 



The pericarp, like the ovary, necessarily possesses a placenta, 

 to which the seeds are attached ; and the same terms are used 

 in describing the different kinds of placentation, as with those 

 of the ovary ; these kinds are usually more evident in the fruit. 

 Having now alluded to the seeds as a component part of the 

 perfect fruit, we must leave their particular examination till 

 we have become acquainted with the structure of the ovules, and 

 now proceed, therefore, to the description of the shell of the 

 fruit or pericarp. 



In the majority of fruits, the pericarp consists simply of the 

 walls of the ovary in a modified state ; but, when the calyx is 

 adherent, it necessarily presents a more complicated structure. 

 The pericarp exhibits three layers or regions (fig. 681), an 

 external, called the epicarj) or exocarp, ep ; a middle, the meso- 

 carp, one ; and an inner, the endocarp, en. The middle layer, 

 being frequently of a fleshy or succulent nature, is also termed the 

 sarcocarp; while the inner layer, from its hardness in some 

 fruits, is then termed the stone or pictamen. When the pericarp 

 consists simply of the matured walls of the ovary, its three 

 parts correspond to the three parenchymatous layers of the 

 lamina of the carpellary leaf : thus the epicarp represents the 

 epidermis of the under surface, or that on the outer surface of 

 the ovary ; the mesocarp corresponds to the general parenchyma 

 of the lamina, or that of the ovary ; and the endocarp to the 

 epidermis on the upper surface, or to the epithelium or inner 

 lining of the ovary. When the calyx is completely united to 



