Chap. YIII. 



EFFECTS OF USE AND DISUSE. 



801 



Xame of Breed. 



Wild mallard 



Aylesbury 



Tutted (Dutch) . . 



Penguin 



Call (from Mr. Fox) 



Weight of entire 

 Skeleton. 

 (N".B. One Metatar- 

 sus and Foot was 

 removed from each 

 skeleton, as it had 

 heen accidentally lost 

 in two cases.) 



Weight of 



Femur, 

 Tibia, and 

 Meiatarsus. 



Or as 



Grains. 



839 



1925 



1404 



871 



717 



Grains. 



54 



164 



111 



75 



57 



1000 :6t 

 1000 : 85 

 1000 :79 

 1000 : 86 

 1000 : 79 



Wild mallard 



Aylesbury 



Tufted (Dutch) .. . 



Penguin , 



Call (from Mr. Baker > 

 Call (from Mr. Fox) '. 





Weight of 



Weight of Skeleton 



Humerus, 



as above. 



Radius and 





Metacarpus. 



Grains. 



Grains. 



839 



97 



1925 



204 



1404 



148 



871 



90 



914 



100 



717 



92 



1000 : 115 

 1000 : 105 

 1CO0: 105 

 1000 : 103 

 1000 : 109 

 1000: 129 



namely, in one of the Call ducks, is in truth no exception, for this 

 bird was constantly in the habit of flying about ; and I have seen 

 it day after day rise from my grounds, and fly for a long time in 

 circles of more than a mile in diameter. In this Call duck there is 

 not only no decrease, but an actual increase in the weight of the 

 wing-bones relatively to those of the wild-duck ; and this probably 

 is consequent on the remarkable lightness and thinness of all the 

 bones of the skeleton. 



Lastly, I weighed the furculum, coracoids, and scapula of a wild 

 duck and of a common domestic duck, and I found that their 

 weight, relatively to that of the whole skeleton, was as one hundred 

 in the former to eighty-nine in the latter ; this shows that these 

 bones in the domestic duck have been reduced eleven per cent, of 

 their due proportional weight. The prominence of the crest of the 

 sternum, relatively to its length, is also much reduced in all the 

 domestic breeds. These changes have evidently been caused by 

 the lessened use of the wings. 



It is well known that several birds, belonging to different 

 Orders, and inhabiting oceanic islands, have their wings 

 greatly reduced in size and are incapable of flight. I sug- 

 gested in my ' Origin of Species ' that, as these birds are not 



