[Quantitative mathematical evaluation of growth studies from the viewpoint of exogenously or genetically influenced variability].

Firstly, the ideas are sketched which serve as the basis for the phenomenologic-mathematical kind of modeling of the body length growth process of man. For proving the biological relevance of the spurts analyzed by numerical procedures one has to consider the social and the biological circumstances in which the growth process takes place. An analysis of longitudinal data series of the body length of (monozygotic) twins will give further hints to the possible meaning of the growth spurts by way of separation of exogenous and of genetic determined endogenous agents on the growth process. The data available for our examinations cover the time interval of the praepubertal and the postpuberal development as well as the time interval in which the puberal growth spurt takes place. The way to proceed in evaluation these time series will be presented.