The kinetics of growth control in a colonial hydroid

Abstract

It is suggested that the cumulative view of growth in which some index of biomass is plotted against time tends to obscure temporal variations in the growth process that might provide evidence of how it is controlled. Experiments with the colonial hydroidCampanularia flexuosashow that the action of a growth control mechanism can be demonstrated by considering changes in specific rates of growth determined at frequent intervals in time. However, it is also necessary to disturb the growth process slightly in order to initiate the action of the control mechanism, and having done so, to isolate the effect of the disturbance on growth and thus the action of the control mechanism. This is done by expressing the specific growth rate of organisms whose growth is disturbed as a percentage of that of control organisms of the same age.