92 DANDENO: SEED-DISPERSION IN RICINUS COMMUNIS 
fore, a measure of the work done in exploding the carpels of the 
plants on one acre would be 
10890 x .0024 = 26.14 horse-powers per second.’ 
This simply means that the work done is equal to that which one 
good strong horse could do in 26 seconds. It does not mean the 
energy that might be required in threshing out the seeds, but it 
means that energy alone which causes the projection of the carpels. 
It should also be observed that the calculated range was an 
approach toward a maximum rather than an average, because no 
account was taken of the fruit which seemed to have simply fallen, 
or of those projected from a disadvantageous position, although 
the energy in the latter case would undoubtedly be the same as 
that exerted in the projection of those which had been discharged 
from a position of advantage. 
_ The energy expanded by the plant is developed directly from 
the atmosphere, coupled with the heat of the sun ; and indirectly 
from the cells and contents built up by the plant. Indeed, it is 
the same quality of energy as that which raises water from the. 
earth into the atmosphere. The part taken by the plant is the 
preparation of carpels of such a form as will store up this energy 
for a time and thus make the best use of it by liberating it a// @ 
once. What this means to the species in successfully contending 
for space in which to grow, may be best illustrated by a mathe- 
matical calculation. 
Starting with a given plant, it may be seen from our measure- 
ments that the ground covered by the seedlings from this Ea 
would be 
In year  3.65?>< 7 square meters, 
In 2 years 7.30?) m@ square meters, 
In 3 years 10.952) = square meters 
In 100 years 365? > 7 = 41.8707 epdereg 105 acres (approx. ). 
This does not seem to be a very large area when the length of 
time is taken into consideration ; but it must be borne in mind that 
this is only ove means the plant has for scattering its seed. It 
takes no account of the washing away by water, or the transpor- 
tation by wind or animals. The calculations are made upon the 
consideration of the fruit as a projectile alone, and from this the 
being of the plant. 
attempt is made to see just how much it has to do with the well- _ 
