THE UNDERLYING IDEA 67 



This naturally led the surplus sparrows out through 

 the many thoroughfares leading from any large city. 

 Where horses went sparrows could follow. Accord- 

 ingly along the great lines of travel this bird found 

 the simple path by which he could enter new territory. 

 Meanwhile box-cars came into our large cities with 

 freight. Sometimes they had carried grain, sometimes 

 cattle. In either case it was not unlikely that a cer- 

 tain amount of grain should be found scattered over 

 the floor of such cars. The sparrow visited these cars 

 for the grain, and it must have been no infrequent 

 accident that a door should be shut upon a group of 

 sparrows, especially in inclement weather, when they 

 were apt to be huddled in a dark corner of the car. 

 These prisoners would be carried to the destination 

 of the car and there liberated, thus producing a new 

 center of what we are now inclined to call infestation. 

 By such means the English sparrow has spread over 

 much the larger portion of the American continent. 

 Few birds are bold enough to visit a railroad car. 

 Of the few who might be tempted, most are timid 

 enough to fly on the first approach of man. Hence 

 they fail to gain this chance of spreading. They must 

 remain in the old crowded home. Meanwhile the 

 sparrow, thus transported, finds a new home with 

 fewer or no sparrows. The struggle is less 

 keen. More of his kind can live. His boldness 



