What Is The Purpose Of The Beads In The Tube With Non-germinating Peas?

What Is The Purpose Of The Beads In The Tube With Non-germinating Peas? Why is it necessary to correct the readings from the peas with the readings from the beads? The beads served as a control variable, therefore, the beads experienced no change in gas volume. Explain the effects of germination (versus non-germination) on pea