The Framework of the Bird 83 



and all but motionless. It is said that, comparatively, 

 the muscular energy is greater and the wing-bones more 

 powerful in a hummingbird than in any other animal. 



Nature has a puzzling way of achieving similar results 

 in a very similar manner in creatures wholly unrelated. 

 We have a good example of this in bats and birds, both 



FIG. 59. Comparison of the size of the keel of the Albatross, Pigeon, and Humming- 

 bird, supposing all to have an equal spread of wing. (Courtesy of Dr. F. A. 

 Lucas.) 



of which have independently learned to propel them- 

 selves through the air by means of their front limbs. 

 If we take the breast-bone of a common bat and that 

 of a small bird and place them together, few persons 

 unacquainted with the bones of the two types could tell 

 which was that of the bat, different as that little crea- 



