Abstract
Qualitative and quantitative estimation of a proteinaceous chymotrypsin inhibitor in tissues of potato plants has revealed a transitory existence in all tissues except xylem, flowers, and seeds, where the inhibitor was not found. The distribution pattern in both aerial tissues and in tubers during development and senescence suggests that the concentrations of this protein in all tissues are influenced by meristematic regions of the plants. The transitory existence coinciding with breaking of apical dominance suggests that in the potato plant the protein may have some role in the process of establishing and maintaining meristematic tissue. A search for the protein in other Solanaceae species and in plants from non-related species has proven unsuccessful.