64 OTHER PLANTS WHICH THROW SEEDS, [chap. 



of the fruit which bears the remains of the flower, is also 

 somewhat eccentric, and, when the seeds are ripe, if 

 it is touched even lightly, the fruit explodes and the 

 seeds are thrown to some distance. The mechanism 

 by which this is effected has been described by 

 Hildebrand. The interior of the fruit is occupied by 

 a loose cellular structure. The central column, or 

 placenta, to which the seeds are attached, lies loosely 

 in this tissue. Through the solution of its earlier 

 attachments, when the fruit is ripe, the column adheres 

 only at the apical end, under the withered remains of 

 the flower, and at the swollen side. When the fruit 

 bursts the placenta unrolls, and thus hurls the seeds to 

 some distance, being even itself sometimes also torn 

 away from its attachment. 



Other cases of projected seeds are afibrded by 

 Impatiens, Hura, one of the Euphorbicz, Collomia, 

 Oxalis, some species allied to Acanthus, and by 

 Arceuthobium, a plant allied to the Mistletoe, and 

 parasitic on Juniper, which ejects its seeds to a 

 distance of several feet, throwing them thus from 

 one tree to another. 



Evenihose species which do not eject their seeds 

 often have them so placed with reference to the 

 capsule that they only leave it if swung or jerked by 

 a high wind. In the case of trees, even seeds with 

 no special adaptation for dispersion must in this 

 manner be often carried to no little distance ; and 

 to a certain, though less extent, this must hold good 

 even with herbaceous plants. It throws light on the, 

 at first sight, curious fact that in so many plants with 

 small, heavy seeds, the capsules open not at the 



