314 THE WORLD OF LIFE CHAP. 



produced annually, and it is only at long intervals of time, 

 when any of the various causes above referred to have left a 

 space unoccupied, that a few seeds germinate, and the best 

 fitted survives to grow into a tree which may replace its 

 predecessor. 



But when every year ten thousand millions of seeds fall 

 and cannot produce a tree that comes to maturity, any cause 

 which favoured their wider dispersal would be advantageous, 

 even though accompanied by very great destruction of seeds, 

 and such a cause is found when they serve as food to 

 herbivorous mammals. For most of these go in herds, 

 such as swine, peccaries, deer, cattle, horses, etc., and when 

 such animals are startled while feeding and scamper away, 

 two results, useful to the species whose fruit they are feeding 

 upon, follow. As the acorns, chestnuts, etc., usually lie thickly 

 on the ground, some will be driven or kicked along with 

 the herd ; and this being repeated many times during a 

 season and year after year, a number of seeds are scattered 

 beyond the limits of the parent trees. By this process seeds 

 will often reach places they would not attain by ordinary 

 means, and may thus be effective in extending the range of 

 the species. It would also often happen that seeds would 

 be trodden into soft or wet ground and thus be actually 

 planted by the devouring animals ; and being in this case 

 placed out of sight till the herds had left the district would 

 have a better chance of coming to maturity. 



Now one such success in a year would more than 

 compensate to the species for millions of seeds devoured, 

 and it would therefore be beneficial to a species to produce 

 nuts or seeds of large size and in great quantities in order 

 to attract numbers of mammals to feed on them. This is 

 quite in accordance with nature's methods in other cases, as 

 Darwin has shown in the case of pollen. The very curious 

 fact of the Brazil-nut having such a very hard shell to the 

 triangular seeds and a still harder covering to the globular 

 fruit, which falls from the very lofty trees without opening, 

 and has to be broken open with an axe by the seed-collectors, 

 is another example. This is said not to open naturally to 

 let the seed escape for a year or more ; and this fact, with 

 its almost perfect globular form, would facilitate its being 



