82 THE FLIGHT OF BIRDS 
radius) is pulled toygrds the body when the elbow 
is straightened and this straightens the wrist. A 
further result inevitably accompanies the first 
straightening movement. ‘There is an elastic liga- 
ment that stretches from the armpit to the extremity 
of the digits. Through this pass all the secondary 
flight-feathers and, in every bird in which I have 
traced its course, all the primaries (those that spring 
from the hand). Part of this ligament is shown in 
Fig. 24. 
Wing viewed from below (after Alix, with a slight alteration, 
see text). AM: Muscle and tendon supporting anterior mem- 
brane, D1: Digit 1. El: Elastic ligament. F: Flexor carpi 
ulnaris, dividing into two. T: Tendons connecting muscle with 
quills. 
figure 24. But it is easy to see the whole of it in 
any bird’s wing when the small covering feathers 
have been removed. The straightening of the wing 
stretches the ligament and the great flight-feathers 
spread like a fan.* (See Pl. x1.) 
* There are differences in different families. In some the liga- 
ment, instead of being pierced by the quills, fastens only to their 
under-side. 
