THE SCENTED CALLA 



a very large proportion of these birds died of 

 starvation. 



In some cases forty or fifty birds would be 

 found starved to death in a single bird-house. 



There are entire regions in New EngUmd 

 to-day where the martin is a rare or unknown 

 bird, although prior to 1901 it was abundant. 



Now we may reasonably assume that any 

 individual martins that escaped were those that 

 had either greater powers of flight or a stronger 

 inherent tendency to make wide flights in search 

 of food than their fellows. The few individuals 

 thus saved furnish us a concrete example of the 

 survival of the fittest through natural selection. 

 And this illustration is cited at length because it 

 makes tangible the fact, to which I shall have 

 occasion to revert time and again, that the 

 processes of nature through which species have 

 been developed in the past are still in operation 

 everywhere about us. 



Many people are disposed to think of natural 

 selection as a principle referring to past times 

 and to the development of organisms long since 

 perfected. 



In point of fact past times are like present 

 times in the operation of their laws. The 

 re-actions between organism and environment are 

 now what they always were. No race is perfected, 



[87] 



