THE FR^IT AND THE SEED 



273 



Berries have no stony endocarp, and their seeds are enclosed 

 directly by the pulp. The number of the carpels forming the 

 berry is twp in Chilli, three in Banana, five in Papaw. The 

 Chilli and Banana have axile, and the Papaw parietal placen- 

 tation. 



C How the seeds are dispersed. 



It is not enough that fruits should allow their seeds to escape. 

 If they fall down and begin life again directly under the leaves 

 of the parent plant, they cannot, as already stated, get sufficient 

 light and air, but finding only a soil from which a great deal 

 of the plant-food had already been extracted by the mother- 

 plant, they must starve. To ensure the dispersion of the seeds 

 over a wide area, various wonderful provisions are made. As 

 the plants cannot move of themselves, they often make use of 

 the agency of running water, of wind, animals and birds, and 

 with their help undertake long 

 journeys to distant countries, and 

 even cross oceans. 



{a) Dispersed by mechani- 

 cal contrivances. — Some plants 

 contain within themselves the 

 means necessary to scatter the 

 seeds. This is in some cases a 

 spring apparatus by which the 

 seeds are thrown away from the 

 parent plant, as in the capsules of 

 the Acanthacese or in the Balsams. 

 "The seed-pod is generally in a 

 state of tension, due to the gradual 

 drying up of the tissue. Then a 

 puff of wind, a slight blow, or even 

 a change in the atmospheric con- 

 dition of the air, gives the final 



impetus, causing the pod to burst with such force that seeds are 

 thrown out in all directions" {Brightiven). 



18 



Fig. 271.— Capsule of a Balsam: 

 1. closed, 2, exploding and scatter- 

 ing- the Seeds. 



