RESPECTABLE AND DISREPUTABLE RELATIVES 51 



inimical to it ; it even takes advantage of it. 

 But it is no more dependent upon it than any other 

 member of the finch family. Thus it may be said 

 to be a healthy success. 



How does the case stand with the house-sparrow, 

 commonly called ubiquitous? As a matter of fact, 

 it is not ubiquitous by any means. There is hardly 

 a country in the world to-day in which the house- 

 sparrow, or one of its local races, does not abound, 

 but in each and every one of them its area is 

 almost strictly the area of cultivation. There are 

 still vast expanses of Russia where it is unknown, 

 though it faithfully follows upon the heels of the 

 cultivator when he breaks open new ground. Even 

 in Scotland there are considerable tracts where it 

 is unknown a glen which has neither habitation 

 nor cultivation is a place where it cannot live. 

 In short, the house -sparrow is a parasite, and 

 despite its seeming success there is that precarious- 

 ness in its state incident to the state of all 

 parasites. It is sometimes spoken of as the " avian 

 rat," but it is really more of a parasite on man- 

 kind than the rat. The rat enters into and enjoys 

 the fruits of human industry to the full, but it 

 can get on without them. There are rats on the 

 seashore far from human works, and rats have 

 been trapped very near the top of our highest 

 mountains. To these and many more likely places 

 the house -sparrow does not penetrate. 



What does all this imply? It probably implies 

 that at no distant date, biologically speaking, the 

 house-sparrow was a creature of much more 

 limited range than 'its cousin the tree-sparrow, 



