QUANTITATIVE STUDIES OF THE FACTORS GOVERNING THE RATE OF REGENERATION IN TUBULARIA

Abstract

1. The rate of regeneration of Tubularia has been measured by the formula R = πr²L/t where r = radius of cross-section, L = length of regenerate, t = time in hours for formation of primordium or the time in hours for emergence of the fully formed hydranth. 2. The rate of regeneration of isolated parts of the stem decreases rapidly from the distal to more proximal regions. An increase in the length of stem adjacent to a regenerating end increases the rate of its regeneration. 3. When two regenerating regions are competing they partition the effect of adding the middle region of the stem if the stem is long. If the stem is short the distal end becomes dominant and inhibits the proximal end. 4. A method has been devised for measuring dominance by expressing it as the percentage reduction in rate of regeneration due to the presence of the distal hydranth. 5. The circulation within the stem of Tubularia has been blocked by means of injection of a drop of oil with the result that the dominance (inhibition) exercised by the distal regenerating end over the proximal end is blocked. 6. A generalized mechanism based on a synthetic factor E in the cells and a circulatory factor S is suggested as a formal explanation of the phenomenon of dominance.