FEET OF LONG-WINGED BIRDS. 295 



In the animal structure we can also examine all the 

 parts, and, comparing them with what they do in one 

 case, we can form an appropriate judgment of what 

 they can do in another. We can say, for instance, 

 of the action of a foot in swimming, that it is a 

 "function" of certain bones, muscles, tendons, and 

 membranes, and other parts, all of which may be 

 eliminated by the knife of the dissector. But we do 

 not thus arrive at the specific action of the foot, either 

 in power or in mode, for that is also a " function " of 

 the energy of life in the animal ; and so far from being 

 able to express this energy in terms of any known 

 or measurable quantities, we have no expression at 

 all involving it, but that very compound action, the 

 principles of which we seek thus in vain to analyse. 



But even this, mortifying as it is to those who 

 labour to appear wise, is fraught with the same ad- 

 vantages and pleasure which are found everywhere 

 in nature. The animal cannot be wholly brought 

 into the closet, so as that the scientific recluse can 

 become fully acquainted with it there, at the sacrifice 

 of much of his health, usefulness, and pleasure. He 

 must go to field and flood, and see the creatures, 

 otherwise he may dream out the years of Methuselah 

 (if the canker of his seclusion shall not eat him up in 

 the twentieth part of that long period), without one 

 moment of awakening to reality and knowledge. 

 Thus, as it were, the coyness of nature is one of her 

 principal fascinations, and he who would secure her 

 favour must woo her as a bride, which, both in the 

 fact and the figure, is the only path in which pleasure 

 and profit are inseparable. 



FEET OF THE LONGIPENNES. 



As birds of this group all depend more on the wing 



