THE GAS PLANT. 
23 
against each other by wind or animal, or the carpel presses later¬ 
ally or from each extremity, a sharp explosion follows as the 
half-endocarps complete their twisting, thus liberating the thin 
placenta and throwing out the seeds. When left to themselves in 
a quiet place where there is no artificial pressure, the tension of 
the endocarp at length forces its way out, sometimes sending one 
Fig. 28. A, half of endocarp, enlarged, to show its twisted form after 
leaving carpel; B, seed enlarged; C, placenta enlarged. 
or both seeds as far as seventeen feet, possibly in some cases 
aided somewhat by the wind. The black, smooth seeds are nearly 
the shape of a pear which is spherical with a short neck. The 
seed is nearly 45 mm. long, by 3 mm. or more in transverse diam¬ 
eter. In size they are much like those of Vicia saliva. 
