The Free Space of Citrus Leaf Slices

Abstract

Measurements of ³⁶Cl and ²²Na efflux have been used to estimate water free space and Donnan free space in Citrus (orange) leaf slices. The water free space within the slices amounts to about 0.025 ml/g fresh weight, suggesting that there is little infiltration of bathing solution into intercellular air spaces. The exchangeable cations of the Donnan free space within the slices total 20-25 μ-equiv/g fresh weight, and these values appear to reflect the exchange properties of the cell walls. The role of the free space as a 'reservoir' for ions in the intact leaf is discussed.