54 _ CLASS-BOOK OF BOTANY. 
sides of these artificial legumes together you will get a model 
showing approximately the structure of a 2- or more-celled 
ovary with axile placentation. In thig 
it is clear that the margins of the car. 
pellary leaves all meet in the centre, or 
axis, of the ovary; that the midribs are 
meee bn eicbeceee- -* 
AYE 
ee re er as 
ee ae 
ae 
‘aa 
Fig. 86. Form of paper 
model of carpellary 
leaf. 
Fig. 87. Three carpellary leaves folded 
so that their margins meet in the 
centre. 
at the points marked ds ; and that each dissepiment is made 
up of portions of the blades of two adjoining carpellary leaves. 
In many cases these dissepiments have either wholly or par- 
tially disappeared, and then 
we have a 1-celled ovary with 
free-central or basal placenta- 
tion (the dotted lines indicating 
where the septa have been). 
Now, if we have a clear 
idea of this derivation of syn- 
carpous pistils from modified 
leaves which bear the ovules 
on their margins, we are In a 
Fig. 88. Transverse section of better position to understand 
three carpellary leaves, their the mode of dehiscence of varl- 
ene ie pind chap alot ous fruits. It has been stated 
neue 1e1r bs] ! § - i 
sorbed, thus sieiielig aes already that & number of ae 
central placentation. are indehiscent —e.g., nuls, 
drupes, berries, &c.—and im 
these the seeds are liberated by the decay of the pert 
carp; but a large section of dry fruits dehisce, and thus 
scatter their seeds, and it is to the mode in which this 1s 
brought about that we will now address ourselves. The 
simplest form of dehiscent fruit is, as we have seen, the 
legume, in which the carpel splits along both sutures: only 
one leguine is produced by each flower (p. 37). The follicle 
is likewise composed of a single carpel, which splits along the 
ventral suture only : two or more follicles always result from 
