Muscles and Nerves ' 191 



we shall see a tangle of bundles of red flesh the muscles 

 which unite to make the arm of a bird such an exquisite 

 flying-machine. Where a muscle narrows and is fastened 

 to a bone, its fibres merge into a thin, tough white cord 



FIG. 140. Model of bird's foot, showing perching tendons; toes extended. 



a tendon. This is not elastic like the main portion of 

 the muscle, but is much more tough. 



In the slender legs and feet of birds there is little more 

 than bone, tendon, and skin. The tendons which clasp 

 and unclasp the toes are very interesting, and if we will 



