DEHISCENCE OF FRUITS. 301 
sutures can alone be observed externally, as the ventral sutures 
of the component ovaries are turned towards, and meet in the 
axis of the flower, and are hence removed from view ; it follows 
also that the number of dorsal sutures will necessarily correspond 
to the number of component ovaries of which such an ovary is 
formed. In a fruit presenting similar characters, we find of 
course a similar disposition of the sutures. When an ovary, on 
the contrary, is formed of the blades of two or more carpellary 
leaves, the margins of which are not inflected, or only partially 
so, and therefore one-celled, and the placentation parietal or free 
central, both ventral and dorsal sutures may be observed exter- 
nally alternating with each other. The fruit, which is formed 
in a similar manner, necessarily presents a similar alternation of 
the sutures on its external surface. 
Dehiscence.—The pericarp at varying periods, but commonly 
when the fruit is ripe, either opens, so as to allow the seed or 
seeds to escape ; or it remains closed, and the seeds can then 
only become free by its rupture or decay. In the former case 
the fruit is said to be dehiscent ; in the latter, indehiscent. Those 
fruits, such as the Nut, Cherry, Apricot, Plum, and Date, which 
have very hard or fleshy pericarps, are usually indehiscent. 
Dehiscent fruits open in various ways :—Ilst. By splitting 
longitudinally in the line of one or both of the sutures ; or at 
the junction of the component carpels only ; or at these points 
as well as at the dorsal sutures. In all the above cases the pieces 
into which the fruit separates are called valves, and these valves, 
when the fruit is normal in its structure, are either equal in 
number to the cells, or component carpels, or they are twice as 
numerous. Thus in fruits formed of a single carpel, which only 
open by the ventral or dorsal suture, there will be only one valve 
(figs. 666 and 667), corresponding to the one carpel ; but if the 
carpels open by both sutures (jig. 668), there will be two valves. 
In fruits formed of compound ovaries composed of several cells, 
the valves will be equal in number to the component carpels, if 
the dehiscence only takes place by the dorsal suture (figs. 672- 
674), or in the line of union of the component ovaries (figs. 669- 
671) ; or they will be double the number, if the dehiscence takes 
place by both these parts. In compound one-celled fruits, the 
valves will be equal in number to the component carpels, if the 
dehiscence occurs only by the ventral ( fig. 680) or dorsal sutures 
681); or double the number, if by both sutures. When there 
is a distinct axis left after the separation of the valves, this is 
called the columella (fig. 675, a). According to the number of 
valves, the fruit is described as one-valved, two-valved, three- 
valved, or many-valved. 
2nd. Dehiscence, instead of taking place longitudinally, or in 
a valvular manner, sometimes occurs in a transverse direction, 
by which the upper part of the fruit separates from the lower 
like the lid from a jar or box. And 3rd. It may take place in an 
