Abstract
1. Sections of rice, wheat and mint plants were soaked in acidic buffer solutions containing some different cations. It was found that the solutions containing cations kept their pH, not to decrease highly and the less its hydration was, the more largely it was influenced. 2. In the mint rhyzome, the absorption of free acid did not decrease by addition of cations, but the cations of smaller hydration were absorbed more easily, and their respirations also did not decrease. It was confirmed that the pH value depended also on the respiration. 3. In comparing among various crop plants, the more easily its pH decreased, the more easily its respiration decreased. Sometimes judging from the grade of acid-resisting ability, pH valuet seemed to be influenced more largely than Al in some crop plants.
