The Lungs.~--We do not drink air as the frog does, but like the frog we have an air-bag in our bodies.

Our air-bag has to be emptied and filled so often that we cannot live under water long at a time, as a frog does.

We call this air-bag the lungs.

We have learned before that the lungs are in the chest.

We need so much air and have to change the air in our lungs so often that we would not have time to swallow it as a frog does.