THE ELIMINATION OF THE UNFIT. 219 



ency toward conservatism on the part of the survivors. In 

 the single exceptional case the numbers are not very different, 

 32 and 31. Granting this exception to the uniformity in the 

 figures, it is exceedingly interesting to examine the series. In 

 respect to length, the birds which perished had an average 

 departure from the ideal mean expressed by the number 3.48, 

 while the average departure of the birds which survived was 

 only 2.51, or, expressed in tabular form: 



In respect to length, 3.48 is greater than 2.51. 



" " " alar extent, 4.60 " 4.20. 



" " " weight, 12.6 " " " 10.9. 



" " length of head, 5.64 " " " 5.51. 



" " " " " humerus, 20.1 " " " 16.0. 



" " " " " femur, 20.0 " " " 14.0. 



" " " " " tibio-tarsus, 33.8 " " " 29.4. 



" u " width of head, 12. " " " 10., but 



" " " length of keel, 31. " less " 32. 



A series of eight consecutive cases like the above, all point- 

 ing in the same direction, can hardly be considered accidental. 

 To summarize : 



(1) We have found that there are fundamental differences 

 between the surviving birds and those eliminated, and we 

 conclude that the birds which survived survived because they 

 possessed certain structural characters, and that the birds which 

 perished perished not through accident, but because they did 

 not possess certain structural characters which would have 

 enabled them to withstand the severity of the test imposed 

 by nature ; they were eliminated because they were unfit. 



(2) The process of selective elimination is most severe with 

 extremely variable individuals, no matter in what direction the 

 variations may occur. It is quite as dangerous to be conspicu- 

 ously above a certain standard of organic excellence as it is to 

 be conspicuously below the standard. It is the type that nature 

 favors. 



(3) Disregard of structural qualifications finally produces a 

 throng of degenerates, whose destruction will follow the arrival 

 of adversity. 



