STRUCTURE OF FRUIT. J 57 



Let us suppose, now (and of this there are numberless 

 examples), that the two retreating faces of the carpels 

 are so united together that they cannot separate, and 

 that, notwithstanding, the fruit must open, and this 

 always happens when, if not fleshy, it is filled with 

 seeds. There takes place then a Dehiscence by 

 Rupture, and this may be presented under six different 

 forms, viz. : — 



1st. (And this is the most frequent case), the de- 

 hiscence takes place along the dorsal nerve, or middle 

 line at the back of the carpel ; this is what we call 

 Loculicidal dehiscence, because it occurs in the 

 middle of the cells ; in this case, one is always inclined, 

 at first sight (and I myself, with most botanists, have 

 for a long time committed this error), to take for the 

 primitive elements of the fruit, not the carpels properly 

 so called, but the Mediastins, that is to say, the 

 bodies formed by the halves of two carpels united 

 together by their retreating faces ; it is in this sense, 

 founded only upon appearance, that we have called 

 Valve the outer part of the mediastin, although really 

 formed of two semi-valves, and that we have said that it 

 bears the partition upon the middle of its inner part, 

 although this partition, really double, arises from the two 

 margins of neighbouring valves. This organization is 

 found in Liliaceae, Ericinese, Tiliaceae, See. &c. It is 

 modified, like septicidal dehiscence, by the existence or 

 non-existence of the central axis, and by the more or 

 less great degree of adhesion of the placentae, either 

 with each other or with the axis. Thus, in the Irideae, 

 all of which have loculicidal dehiscence, the placenta? 

 remain united, forming a false axis in Belamcanda, 

 whilst they accompany the partitions in most of the 

 others, and especially in Iris. 



2d. It happens in some families, such as the Cruciferas. 



