20 LUTHER BURBANK 



to offspring that would constitute a long-winged, 

 swift-flying race. 



Take the following incident as a tangible illus- 

 tration. 



In the summer of 1904 it chanced that there 

 was a severe drought in New England and there 

 were entire regions in which the insects upon 

 which the common house martin feeds failed to 

 be hatched at the usual time. The result was 

 that there was dearth of food for the martins, and 

 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 England to- 

 day where the martin is a rare or unknown 

 bird, although prior to 1904 it was abundant. 



Now, we may reasonably assume that any in- 

 dividual 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 proc- 

 esses of nature through which species have been 



