TRANSVERSE OR CIRCUMSCISSILE DEHISCENCE. 507 
compare their position with the sepals or divisions of the calyx. 
Thus, as the different whorls of the flower in a regular arrange- 
ment alternate with one another, the component carpels of the 
fruit should alternate with the divisions or sepals of the calyx. 
If the fruit therefore separates into as many portions as there 
are parts or sepals to the calyx, and if these valves are then 
placed alternate to them, they represent the component carpels, 
and the dehiscence is consequently analogous to the septicidal 
form ; if, on the contrary, the valves are equal and opposite to 
the sepals or divisions of the calyx, each valve is composed of 
the adjoining halves of two carpels, and the dehiscence is 
analogous to the loculicidal form. Sometimes the number of 
valves is double that of the calycine segments or sepals, in 
which case each valve is formed of half a carpel, the dehiscence 
of the fruit having taken place both by its dorsal and ventral 
sutures. 
In all the above varieties of valvular dehiscence, the separa- 
tion may either take place from above downwards, which is by 
far the more usual form (figs. 669, 672, 677, and 679) ; or occa- 
sionally from below upwards, as in the Celandine (fig. 683), and 
universally in Cruciferous plants (fig. 682). 
2. TRANSVERSE OR CIRCUMSCISSILE DEHISCENCE.—In this 
kind of dehiscence the opening takes place by a transverse 
fissure through the pericarp across the sutures, 
so that the upper part is separated from the Fra. 684. 
lower like the lid of a jar or box, as in 
Hyoscyamus (fig. -684) and Anagallis (fig. 
709). Sometimes the dehiscence only takes 
place half round the fruit, as in Jeffersoiia, 
in which case the lid remains attached to the 
pericarp on one side, as by a hinge. The _ ape 
fruits which present transverse dehiscence ” ae . ae 
may be supposed to be formed either of car- = mus) with trans- 
pellary leaves in which the lamine are articu- hae Me rin e 
lated to the petioles, as.in the Orange (fig. ed a pyxis (page 
320), and which become separated at the 316). 
points of articulation, so that the united 
petioles form the lower part of the fruit, and the united laminz 
the upper ; or they may result from the prolongation and hollow- 
ing out of the thalamus, and the articulation of the carpellary 
leaves to its circumference, so that in the dehiscence the 
lower part of the fruit is formed by the concave thalamus, and 
the upper part by the carpellary leaves ; thus resembling the 
separation of the calyx in Eschscholtzia (page 229) from the 
thalamus. 
In the Monkey-pot (fig. 685), the lower part of the ovary is 
adherent to the tube of the calyx, and the upper portion is 
free ; and when dehiscence takes place, it does so in a transverse 
manner and at the part where the upper free portion joins the 
X2 
