Rapid Changes in Permeability of Cell Membranes to Water Brought About by Carbon Dioxide & Oxygen.

on the permeability of protoplasmic membranes to water. Our experimental tissue was the hypocotyl of Helianthus annuus. We have observed the effect of such factors on the permeability of the cells toward water passing both in the inward and in the outward directions. The rate of entry of water into uniform segments of tissue is a function of A, the difference in diffusion pressure deficit (DPD) between the cells and the external medium, and B, the permeability of the protoplasm to water. Since our interest lay in B, means had to be dlevised of keeping A as nearly constant as possible between treatments. \Ve have met this requirement by ensuring that the DPD of the tissue was so large that any changes in DPD resulting from cellular processes during the period