138 THE WORLD OE LIFE 



Brown University, Providence, Rhode Island, after a very 

 severe storm of snow, sleet, and rain, 136 common sparrows 

 were found benumbed on the ground, and were collected and 

 brought to the Anatomical Laboratory. They were laid on 

 the floor of a warmed room to see if any of them were alive, 

 where after a short time 72 of them revived while 64 perished. 

 The happy thought occurred to Professor LI. C. Bumpus, that 

 here was an opportunity of discovering whether there were any 

 visible characters indicating why some of these birds, under 

 exactly similar conditions, w^ere destroyed while others sur- 

 vived. He therefore made a very minute and careful exami- 

 nation of all the birds, living and dead, with very interesting 

 results, of which the following is a summary: 



(1) Sex. — About two- thirds were males, one-third females. 

 Of the former 51 lived, 36 died; of the latter 21 lived, 28 

 died, showing a decided superiority of the males in resisting 

 cold and wet. 



(2) Size. — Here the comparison was made of male adult 

 birds, male young, and females, separately; in all three of 

 these groups those which died were larger than those which 

 sundved. The difference was not very great, but it was clearly 

 marked, and as it occurred in all three groups it could not 

 possibly be imputed to chance. 



(3) Weight. — This gives the same result as in the last case, 

 the survivors being lighter than those w^hich died, by the con- 

 siderable proportion of one twenty-fifth. 



(4) Length of the Sternum (breast-bone). — This character 

 gives a rather unexpected result, those birds which survived 

 having a decidedly longer sternum than those which perished. 

 The difference is about .013 (a little more than one-hundredth) 

 of the total length; but as the smaller birds on the whole 

 survived, these evidently had their sterna proportionally very 

 long. ]^ow the sternum is an indication of the size of the 

 pectoral muscles w^hich move the wings in flight. The sur- 

 viving birds therefore were those that could fly quickest and 

 longest, and this probably led to the more rapid production 



