50 DARWINISM AND THE PROBLEMS OF LIFE 



years, and efforts have been made to plant thickets 

 alongside the railway on some of the less converted 

 estates. In connection with one of these experiments 

 in Thuringia nests have been found on an average 

 every thirty yards, which is a decided success when 

 we consider the dislike of the birds for new plantations. 

 However, the times will not wait; cultivated land is 

 changing its appearance more and more, and our 

 old friends are disappearing. Few of them can adapt 

 themselves to the new conditions, like the black-bird, 

 which is gradually becoming a town-bird, and now 

 pours out its song from the roof of a house or even 

 the chimney of a factory, instead of from the top 

 «f a rain-dewed tree. 



Other birds are not deprived of their nesting places 

 in the advance of civilisation ; some, in fact, find them 

 in greater abundance. The chaffinch, which nests on 

 trees, is never at a loss for a spot, and we hear its 

 jubilant cry the most frequently of all. The spread 

 of the fields gives more room for nesting to the lark, 

 which is also on the increase. This is an excellent 

 proof of the correctness of what I said, since its nest 

 lies in the ground, exposed to innumerable enemies. 



But most birds, especially our best singers, breed 

 in the bush, and they are steadily diminishing owing 

 to the destruction of their nesting-places. And the 

 same is happening to the fishes. 



The rivers are controlled, and the standing waters, 

 in which the inhabitants like to lay their spawn, are 

 disappearing. The Rhine-salmon comes less and less 

 frequently up-stream, and if it were not for the partial 



