272 WALKING AND CLIMBING FEET. 



vertical plane and parallel to the mesial plane of the 

 body, without any lateral flexure, then the bird will 

 walk firmly; and whether its inarch shall be quick or 

 slow upon one kind of surface or another is made out 

 by the details, the relative length of the member, and 

 the form and magnitude of the toes and claws. If a 

 man has his knees or his ankle-joints with lateral play, 

 or ^^-ith a twist inward at the knees, or more espe- 

 cially with a twist either way at the ankles, he walks 

 never a bit the better though his feet may happen to 

 be, as is often the case with inward-twisted ankles, 

 as broad as shovels. It is also impossible even to 

 imagine members more finely organised for their 

 proper use than the toes of long-armed apes and spi- 

 der monkeys ; and yet, from the twist of the ankle, 

 which is an outward twist, or one which turns the sole 

 of the foot inwards, they walk not only with great 

 awkwardness but with great pain. 



The articulation of the toes of a bird, answers in 

 anatomical arrangement to the metatarsal joints of 

 the toes in man ; but in walking it answers to the 

 ankle-joint. If this joint is firm, and the joints above 

 it so articulated as that the weight of the bird comes 

 perpendicularly upon its centre, then the step of the 

 bird will be firm ; but if this joint is loose, or even if 

 the strain takes it in an oblique direction, the bird 

 will wriggle or waddle, and waste in rolling from side 

 to side great part of that muscular exertion which 

 would carry a better set bird straight forward on its 

 way. The woodpecker is straight and firm on these 

 articulations ; and even its capacity of holding-on 

 upon the trees, requires that it should be so. It is 

 not, as we have seen, a clutching climber, which holds 

 on by grasping with the foot, — for even when the 

 woodpecker perches upon a branch for repose, it does 



