192 The Bird 
bend the tarsus back and forth in the leg of a dead chicken, 
the workings of these strands of tissue may be traced 
beneath the scales. Reference to the photograph, where 
catgut replaces these tendons, will make their workings 
still more plain. 
Fic. 141.—Same as Fig. 140; toes contracted. 
Many birds cannot flex the leg without drawing the 
toes up, and we may be sure that these birds are safe 
when they perch; the closer they sit to the branch the 
tighter becomes their grip. But this safety mechanism 
is not found in all perching birds by any means (Fig. 
143). 
A strange thing about muscles is that there are fine 
