[Quantitative analytical registration of body-length growth in man]

Measured values concerning the body hight growth process of male human beings, and reaching from praenatal to adult state are taken from anthropometric literature. After a discussion of the mathematical tools for description (differential equation, analytical function), and of the problems connected with subdividing the whole growth period in subsequent periods the results of numerical adjustments of growth functions to measured courses of these subperiods are presented. The obtained goodness of fit is excellent so that for the purpose of formal quantitative description of the whole growth process a set of mathematical functions is available. Each of these expressions is effective only in the time interval of the corresponding growth subperiod. This set of mathematical functions will provide a objective basis for further investigations, especially for comparisons between populations, and for a mathematical analysis of acceleration phenomena in development. In the last part of the paper a mathematical-phenomenological model for the growth process is sketched. The main features of this model consist in a subdividing of the whole process in growth parts with a biological meaning, and in a mathematical description of these parts which are mutually independent but superposing one with another. Therefore the number of growth parts and also of mathematical terms are determined by biological (theoretical or phenomenological) arguments. Now each of these calculated function terms is valid for the whole time intervals in which the body hight growth process performs. The entirety of all these terms gives a seamless steady description of the changes of the growth variable in time.