92 THE STRUCTURE AND LIFE OF BIRDS cuwap. 
thigh-joint moved rather more than half an inch, the 
movement of the sternum being almost too slight to 
measure. I do not wish to represent this experiment 
as one of much value. However, the conditions of 
flight were so far reproduced that the weight of the 
body was hanging upon the wings and so hindering 
the movement of the breast while leaving the back 
free ; it is true, there was none of the pressure—which 
during flight must be very great—of the wings upon 
the coracoids and clavicles. But would not the only 
effect of this pressure be to render the breastbone and 
the bones united with it still less ready to move? 
When a bird flies with his body sloping upward, as 
he always does when he wishes to rise, I believe the 
process of breathing will be the same, with the 
difference that the Latissimus Dorsi will ngt contract 
sufficiently to raise the back nearly to the horizontal. 
There is yet another posture which birds commonly 
adopt, and in which the problem of breathing does not 
seem altogether a simple one. A chicken sleeps with its 
breast resting on its perch. And gulls, geese, ducks, 
and other birds will often lie with their breasts on the 
ground. In this case the movement of the breast is 
out of the question, and sometimes ocular evidence 
may be obtained that it is the back that moves. | 
have spent a considerable time in watching a Chinese 
goose at the Zoological Gardens, while it lay on its 
‘breast and uttered loud and uncouth noises. The 
hinder part of the back rose visibly. And this was 
not surprising, for there was no weight upon the legs, 
and it is this of course which makes back-breathing 
impossible when the bird is in a standing posture. 
