The Osmotic Change during Auxin-Induced Water Uptake by Potato Tissue

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Abstract
Although previous workers have reported that auxin lowers the osmotic concn. of the cell sap of potato tuber tissue, these effects have been rather small. Under new exptl. conditions, a very large naphthaleneacetic acid-induced water uptake by potato (Solanum tuberosum var. Katahdin) disks was obtained. Correspondingly, it was shown that the auxin causes a large and clear decrease in the osmotic concn. (detd. cryoscopically) of the expressed sap. This decrease can be accounted for by the increase in volume. It is concluded that auxin-induced water uptake, or growth, cannot be primarily the result of the formation of additional osmotically active substances in the cell.