Evolution of the Lung

I’m getting over pneumonia so in a vain attempt to make lemonade out of lemons, I’m going to talk about the evolution of the lung.

The lung is one of the major mechanisms– if not the major mechanism– that enabled invasion of the land by animals.

The necessity of lungs is based on the vast difference between gaseous oxygen and oxygen dissolved in water. For one thing, when water passes over the gills of a fish (or crab) it is one fluid (water) passing next to another fluid (blood) across a thin...