300 MODIFICATIONS OF THE PERICARP—SUTURES. 
fruits. Thus in the Peach, Apricot, Cherry, Plum, and most 
other drupaceous fruits (page 311), the separable skin is the 
epicarp ; the pulpy part, which is eaten, the mesocarp or sarco- 
carp; and the stone enclosing the seed, the endocarp or puta- 
men. In the Almond, the seed is enveloped by a thin woody 
shell, constituting the endocarp, which is itself surrounded by a 
thin green layer, formed of the combined mesocarp and epicarp. 
In the Apple and Pear, the skin is the epicarp ; the fleshy part, 
which is eaten, the mesocarp or sarcocarp ; and the core con- 
taining the seeds, the endocarp. A similar disposition of parts 
occurs in the Medlar, except that here the core becomes of a 
stony nature. In the Date the outer brownish skin is the 
epicarp ; the thin paper-like layer enclosing the seed is the 
endocarp ; and the intermediate 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 meso- 
carp and epicarp combined. In the Orange, the outer separable 
rind is composed of the mesocarp and epicarp ; aud the thin 
membranous partitions which divide the pulp into separate 
portions form the endocarp ; the edible pulp itself is a develop- 
ment of succulent parenchyma from the inner lining of the ovary, 
or probably from the placentas only. In the above fruits, and 
numerous others 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, will 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 presented two sutures (page 267) ; one of which 
(fig. 586, vs), called the ventral suture, corresponded to the union 
of the margins of the lamina of the carpellary leaf, and was con- 
sequently turned towards the axis or centre of the flower ; and 
the other, ds, termed the dorsal suture, corresponding to the 
midrib of the lamina, which was directed towards its circum- 
ference. The simple fruit being formed, in most cases, essenti- 
ally of the mature ovary, 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 aslight furrow ; thusin the Peach (fig. 
693), Cherry, Plum, and Apricot, the ventral suture is very evi- 
dent, although the dorsal suture has become nearly effaced ; 
while in the Bladder Senna (jig. 662), Pea, and other fruits of 
the Leguminosz, both dorsal and ventral sutures are clearly 
visible externally. 
In a compound ovary with two or more cells, in which the 
placentation is axile, it must be evident, of course, that the dorsal 
