No. 517] PARENTAL MODIFICATIONS 9 



cold-room descendants is possible. The mean tail length 

 for the former animals is greater in eight of these eleven 

 cases (exceptions starred) ; the mean foot-length is 

 greater in nine of the eleven cases; while the mean ear 

 length is greater in nine cases, and equal in one case. 

 Let us consider the likelihood that such results have been 

 obtained through "chance." What are the probabilities 

 that, in tossing a coin, we shall throw "heads" or "tails" 

 as many as eight times out of eleven? The chances 

 that we shall obtain as great an excess as this (on one 



=0.7i> 16.954 



L.29 ±0 



1.47 ±0.39 17.962 iO.069 1 12.491 



ii.i-j ::;.<-.2 



±0.063; 12.534 ±0.0 5 

 ±0.0571 12.568 ±0.085 

 I ±0.065 



side or the other) are about 5 out of 22, This is admit- 

 tedly not a very unlikely happening. The chances that 

 nine of the eleven will be of one kind are about 1 in 15. 



