PROPERTIES OF CLIMBING FEET. 277 



bird half the size of a parrot could use its wings among 

 them, unless to pass through at some opening ; but 

 the parrot has to range the tree in all directions at 

 the very part of it where wings cannot be used ; and 

 it has to range minutely, because there are always 

 leaves upon those trees, and the leaves of tropical 

 trees are often broad and close. Thus, though the 

 parrot is a tree bird, it seeks its food much in the 

 same manner as a partridge seeks among the corn, 

 or a grouse among the heather ; that is, by compara- 

 tively slow motion, and prying about on all sides as 

 it goes along. Consequently, the organisation most 

 essential to this habit is the one which enables it to 

 get most readily from twig to twig without the use of 

 its wings in any other way than partially opened to 

 assist in keeping its balance. 



The foot, to possess this property, must have the 

 whole of its prehensile action in the toes; and the 

 leg, instead of maintaining one invariable position 

 in assisting the foot in holding on, must be free to 

 move to its utmost stretch in all directions. It is also 

 evident, that unless the parrot could hold on by one 

 foot, and hold on with that foot in any direction, 

 above it, below it, or laterally, it could not make its 

 way ; and even in addition to this, the bill of the 

 parrot is prehensile, and affords the same assist- 

 ance to the feet, as the prehensile tails of those 

 climbing mammalia and reptiles which have that 

 character. 



To accomplish these purposes, the joints in the leg 

 and foot of the parrot must have rolling or oblique 

 motions, in order that, while it holds on with the one 

 foot, it may extend the other as far as its length will 

 permit in any direction ; and it is especially necessary 

 that the joint at the articulation of the toes should 



