Nature's Militia 331 



and indispensable services, of the ' militia.' We have 

 seen something of these, and we have seen, too, how 

 surely punishment has followed where the birds have 

 been exterminated ; but there is a word or two to be 

 said on the other side of the question. 



It is very rash for man to interfere with nature by 

 exterminating any one class of the labourers employed, 

 whether in the tilling or in the protection of the fields, 

 cultivated or uncultivated ; but, at the same time, it is 

 hardly less rash for him to interfere in the other direc- 

 tion, and to encourage these same labourers overmuch ; 

 or even, because they are found useful in one part of 

 the world, to conclude hastily that they must be equally 

 useful in another. 



Thistles do not overwhelm us, and swamp other 

 vegetation, in Europe ; but he was a very rash man 

 who imported a sack of thistle-seed into South 

 America and scattered it broadcast about Valparaiso, 

 with an idea of providing useful fodder for cattle! 

 The thistle took to the soil and climate amazingly, 

 and having nothing to check its increase, as it has at 

 home, quickly spread over large tracts of country, to 

 the great inconvenience of the cultivators. 



Then, someone may be inclined to say, why not 

 import birds to eat the seed ? But things in nature 

 are so exactly balanced that even this step would 

 probably be found to have its disadvantages, and 

 possibly the birds might turn out to be even worse 

 than the thistles. The sparrows imported into the 

 United States, for instance, and at first petted and 

 made much of, have so thriven and multiplied that 

 they are now a pest, and generally hated. But the 

 mischief is done, and is not to be so easily undone. 



