It's called Combinations of Jacksons. Here's the beginning:
I MADE MY first experiments in breathing underwater at the age of nine, in 1943. It was something I needed to learn in life so as to be ready to give my pursuing enemies the slip. At that time they were Nazi spies and Japanese saboteurs.
The trick looked simple enough in the movie serials, which pulled me along from one Saturday to the next with such chapter titles as "Fangs of Doom!" and "In the Scorpion's Lair!" First you cut a reed. You put one end of the reed in your mouth and lay face up, very still, on the bottom of a shallow stream. The other end was projected above the surface of the stream, and through this hollow shaft, as you lay buried alive in water, you breathed.
Agents of the Axis Powers were never far behind me. I could slow them a little with pinecone grenades, but I couldn't stop them. They came crashing through the woods firing their Lugers at me as I raced barefooted for the reed beds of Beech Creek, a last hope. If I could get there in time to make my arrangements, then the agents in their stupid fury would overlook the life-giving reed, one among so many, and, with their boots splashing down eight inches away from my rigid underwater body, go stupidly on their way downstream.