MORPHOLOGY OF THE FRUIT AND SEED 239 



stone enclosing the seed, the endocarp or putamen. In the 

 Almond, the seed is enveloped by a thin woody shell, constitu- 

 ting the endocarp, which is itself surrounded by a thin green 

 layer, formed of the combined mesocarp and epicarp. In the 

 Date the outer brownish skin is the epicarp ; the thin paper- 

 like layer enclosing the seed is the endocarp ; and the inter- 

 mediate pulpy part is the mesocarp or sarcocarp. In the 

 Walnut, the woody shell enveloping the seed, which is commonly 

 termed the nut, is the endocarp ; and the green covering of this, 

 called the husk, consists of the mesocarp and epicarp combined. 

 In these fruits, and in ntunerous others which might be 

 quoted, the different layers of the pericarp are more or less 

 evident ; but in some fruits, as in the Nut, these layers become 

 so blended, that it is difficult, if not impossible, to distinguish 

 them. The examples of fruits now mentioned, together with 

 those previously alluded to, show in a striking manner the very 

 varying nature and origin of the parts which are commonly 

 eaten. 



Sutures. — In describing the structure of the carpel, we found 

 that the ovary presents two sutures ; one of which (fig. 399, 

 vs), called the ventral suture, corresponds to the union of the 

 margins of the lamina of the carpellary leaf, and is consequently 

 turned towards the axis or centre of the flower ; and the other, 

 ds, termed the dorsal suture, corresponds to the midrib of the 

 lamina, which is directed towards its circumference. The 

 simple fruit being formed, in most cases, essentially of the 

 matinee ovar}', also presents two sutures, which are distinguished 

 by similar names. These, like those of the ovary, may be 

 frequently distinguished externally, either by a more or less 

 projecting line, or by a slight furrow ; thus in the Peach (Jig. 

 587), Cherry, Plum, and Apricot, the ventral suture is very 

 evident, although the dorsal suture has become nearly effaced ; 

 while in the Bladder Senna (fig. 506), Pea, and other fruits of 

 the LeguminosEe, both dorsal and ventral sutures are clearly 

 visible externally. 



In a polycarpellary ovarj' with two or more cells, in which 

 the placentation is axile, it must be evident, of course, that the 

 dorsal sutures alone can be observed externall)', as the ventral 

 sutures of the component ovaries are turned towards, and meet 

 in the axis of the f^o^^■er, and are lience removed from view ; it 

 follows also that the number of dorsal sutures corresponds to the 

 number of carpels of which such an ovary is formed. In a 

 fruit presenting similar characters, we find of course a similar 



