The Extension Growth-Time Relationship for<i>Avena</i>Coleoptile Sections

Abstract

1. The growth rates of coleoptile segments supplied with indole-3-acetic acid is not constant with time, but, when the IAA concentration is high, decreases very rapidly. 2. With sufficiently high concentration of IAA, the initial rapid growth may be eventually followed by shrinkage of the tissue. 3. The relation between initial rate of growth and auxin concentration is not significantly different from hyperbolic. 4. The significance of these facts in relation to kinetics of auxin action is dis cussed.