Allometry is the study of how one trait is related to another. Historically, allometry was concerned with how characteristics of an organism change with size. Today, there are three distinct types of allometries studied: ontogenetic allometry - scaling of traits over the developmental time in one individual, static allometry - scaling of traits in different individuals at the same developmental time and evolutionary allometry - scaling of traits measured in different species. Since variation in size at any fixed moment in time is a consequence of growth and ontogenetic allometry, it is of biological interest to investigate the relationship between these three factors. By expressing the growth of two traits through a Gompertz function, it is possible to derive a complex formula for ontogenetic allometry that agrees with the data. Study of individual growth curves shows that there is a relationship between final size, displacement of the function along the x-axis and the growth rate within one trait. There is also a relationship between the final sizes for two different traits, which represents static allometry for fully developed organisms.