! 
90 DANDENO: SEED-DISPERSION IN RICINUS COMMUNIS 
distance. The other two carpels cannot be in so good a position, 
but the plant appears to be able to sacrifice several in order that a 
few seedlings may obtain a place of advantage the following sea- 
son. It sacrifices wo carpels that ove may have the maximum of 
benefit in this respect. 
As the fruit ripens it loses water gradually and begins to split 
open septicidally from the base and keeps on splitting thus, until 
a point is reached about three millimeters from the apex. While 
this is going on, the carpels are not only separating from one 
another, but also from the central column which is a continuation 
of the fruit-stalk. + On three sides of the apical end of this central 
column are the three placental processes. Each projects into the 
locule to some extent, but the seed breaks off early from the 
placenta, leaving this central column wholly separate from the 
three carpels, yet suspending them because the processes referred to. 
extend into each carpel through a comparatively large opening 
near the apical end. The carpels are therefore suspended much 
in the same manner as if hanging upon a peg; but as the three 
are still joined together they cannot be separated entirely from the 
central column until oe of the three is removed. ‘This central 
column, upon separation from the carpels, is left with three pro- 
jecting flanges which, together with the processes referred to, prevent 
any alteration in position of the fruit which might possibly result 
when the carpels become detached from the column. At first 
glance this would seem to make no difference; but, when we 
consider that the carpel first projected will have the greatest 
momentum it is of some importance. The carpel with its dorsal 
side uppermost will have the most sun exposure and will con- 
sequently dry out most quickly. This is the carpel which has the 
best position, and which will most likely reach the maximum 
range. 
A second stage in the process of preparation for actual pro- 
jection may be said to commence after the carpels are entirely free 
from the central column. As the carpel dries out, the dorsal wall _ 
contracts and this contraction produces a pressure which becomes | 
greater and greater as contraction goes on until the carpel gives : j 
way at its weakest point. This is at the apical end a 
are three pairs of tooth-shaped arrangements meeting at a line about — 
three or four millimeters long. Each carpel splits apart at this 
