DISPERSAL OF SEEDS 103 



Moreover a number of succulent fruits are eaten as food by 

 animals of various kinds, especially birds, and the seeds of such 

 fruits pass through the stomach and intestines without injury. 



The protection of the embryo against the action of the 

 digestive liquids of the body is generally afforded by the hard 

 parts of the pericarp, or the seed coats. The alluring or 

 attractive succulent parts of the fruit in drupes — cherry, sloe, and 

 plum, — and in all berries, is the pericarp, or some part of it, while 

 in the strawberry, rose, apple, and hawthorn, the receptacle 

 is the attractive portion. 



In the stone-fruits and hawthorn the hard, bony endocarp 

 protects the embryo while passing through the body of an 

 animal, and in berries the testa of the seed serves the same 

 purpose. In the strawberry and rose-hip the seeds are pro- 

 tected by the hard pericarp of the achenes. 



It will be noticed that when the seeds are unripe and unfit 

 for dispersal the parts of the fruit used as food in all these cases 

 are at first green, sour, and firm in texture. But at the time of 

 ripening of the seeds, or soon afterwards, when they are ready 

 for distribution the parts of the fruit change to some conspicuous 

 colour, become softer and sweeter, and often develope a distinct 

 and characteristic odour. 



Ex. 47. — -Examine the fruits of common weeds and endeavour to find out 

 how the seeds are dispersed in each. 



Ex. 48. — Notice the number and Itinds of seeds and fruits attached to the 

 wool of sheep ; also to the fur of dogs after passing through a dense copse in 

 summer or autumn. 



What means of attachment do the fruits exhibit ? 



Ex. 49. — Look out for evidence of the dispersal of seeds by birds ; 

 (a) Examine the excreta of fieldfares and thrushes in winter. 

 {6) Observe the kinds of shrubs and trees which grow sometimes on 



the face of cliffs and walls of old ruins. Have they mostly 



succulent fruits ? 

 (c) What kinds of fruit have the plants found growing away from the 



ground on old trees? 



