vii FLIGHT 209 



situated on or near the body, arc able to spread the 

 wings and regulate their utmost extremities. It is 

 all-important that it should be so. All the weighty 

 organs must be accumulated in the body. To speak 

 metaphorically, the wings must be made up of very 

 little besides masts, sails, and cordage. 



The great muscles that move the humerus I 

 have already described ; they spring from the breast- 

 bone and neighbouring bones. The muscles that 

 bend or straighten the arm at the elbow arise from 

 the top of the coracoid and from the anterior end of 

 the shoulder-blade respectively. Nearly all their bulk 

 and weight is near the body. One of them, the 

 triceps, does a great work ; it straightens the elbow- 

 joint, whereupon the hand is extended and the great 

 ligaments get to work and spread the feathers, and 

 then only small points remain for small muscles to 

 see to. There arc ten muscles springing from the 

 further end of the humerus. These, of course, 

 are not large, and most of them extend only to the 

 wrist or metacarpal bone. Two of them, however* 

 by the help of tendons move the fingers. Altogether, 

 to do this work, there are five long muscles spring- 

 ing either from the humerus or the ulna. And 

 one of these attaches to the much-reduced thumb, 

 called the bastard wing. 1 There are also no less 

 than eight very small muscles springing from the 

 wrist and metacarpal bones, and filling up the space 

 between the latter. All of these are attached to the 

 fingers or " thumb," which, actually, engrosses no 



1 See p. 42, where it is discussed what fingers in our hand 

 correspond to the three in a bird's wing. 



