SELECTION 165 



to their possessors, though they were de- 

 monstrated to have the high utility of deter- 

 mining survival which is indeed, for the 

 evolutionist, the final criterion of utility. 



Professor Bumpus took 136 benumbed 

 house- sparrows into his laboratory, where 

 72 revived and 64 succumbed. There were 

 general differences of a somewhat subtle sort 

 between those that revived and those that 

 succumbed. General stability of structure 

 was the essential characteristic of the former. 



The fine researches by which the late Pro- 

 fessor Weldon proved discriminate elimination 

 in shore-crabs, and by which Professor Karl 

 Pearson proved a selective death-rate in man, 

 are of the highest importance, but they require 

 more exposition than we can give here. 



We may round off this section with two 

 simple observations whose picturesqueness 

 may emphasize our present point. 



Professor Davenport, of the Carnegie In- 

 stitution for Experimental Evolution, had 

 800 chickens in a field, 80 per cent, white 

 or black and conspicuous, 20 per cent, spotted 

 and inconspicuous. In a short time twenty- 

 four were killed by crows, but only one of 

 the killed was spotted. 



Finally, a kindred and recent field obser- 

 vation of our own. In a heavy snowstorm 



