Means of Dispersal. 31 



Accidents of this sort, however, are not absolutely 

 necessary for the dispersal of the seeds ; for a considerable 

 number, even of such soft seeds as that of the Ivy, are 

 passed with their vitality unimpaired. This is often the 

 case when the bird or other animal has been feeding 

 greedily ; and at such times the bird may throw up great 

 part of its food undigested, especially if it is startled.* 



Birds, especially- young birds, as Professor Lloyd 

 Morgan has shown, learn by experience, and try various 

 unsuitable foods. This must often lead to their eating 

 indigestible, poisonous, or aperient fruits, which are not 

 commonly taken. So many fruits have medicinal qualities 

 that these in many cases may be special adaptations to aid 

 the dispersal of the seeds. The migrating bird in its first 

 year is constantly coming across plants new to it, and this 

 at times when it is too tired and hungry to discriminate. 



Mammals also must have greatly aided the dispersal of 

 seeds in former times, for an ox, a deer, or a horse falling 

 over the cliffs of France would tend to drift with the 

 prevalent south-west wind till it was thrown upon the 

 English Coast, where wolves and foxes would pull it to 

 pieces, dragging the remains beyond the reach of the sea, 

 and perhaps burying parts, with the undigested vegetable 

 food still contained in the stomach. 



It is needless to multiply instances, enough has been 

 said to show that the special modes of transportation 

 studied by Lyell and Darwin, added to the accumulated 

 accidents of some thousands of years, are sufficient to 

 account for the introduction of the whole of our native 

 plants, without the necessity for any continuous land con- 

 nexion between the different islands, or with the Continent. 

 Indeed the constant rain of seeds over our Islands 

 is probably on such a scale that were it not for the 

 * E. M. Langley, Nature, December 15th, 1898. 



