HAYMAKING BEGINS. 105 



ing their position ; so that at last the farmer often posi- 

 tively sows corn-cockles and thistles broadcast with the 

 grain that he scatters on his fields. They go with the 

 seeds to America and Australia, and they live down the 

 native plants in New Zealand or the Cape Colony. 

 What we see in this illustrative example of their seeding 

 is equally true in all their other peculiarities. They 

 have been compelled to adapt themselves to the new 

 conditions by such a stringent selection as seldom or 

 never occurs in natural circumstances. Prairie-fires or 

 inundations take place once in an age, on a single spot 

 at least ; but the animal ploughing of the fields does 

 almost as much every year as these catastrophes can 

 accomplish in a whole century. Indeed, no form of 

 selection is really so severe as that thus unconsciously 

 exercised by man. And when we remember that he 

 has tilled and reaped cereal grains ever since the days 

 when he ground his flint hatchets beneath the primeval 

 beech-forests of prehistoric Europe, it is not surprising 

 that appropriate interloping plants should have had time 

 to develop themselves in his cultivated patches. How- 

 ever small those patches were, they must from the 

 'beginning have possessed their own peculiar types of 

 weeds. 



